{"id":4549,"date":"2019-06-24T13:01:06","date_gmt":"2019-06-24T13:01:06","guid":{"rendered":"https:\/\/pressbooks.ccconline.org\/acchumanbio\/chapter\/5-7-mutations-3\/"},"modified":"2023-11-30T17:57:32","modified_gmt":"2023-11-30T17:57:32","slug":"5-7-mutations-3","status":"publish","type":"chapter","link":"https:\/\/pressbooks.ccconline.org\/acchumanbio\/chapter\/5-7-mutations-3\/","title":{"raw":"5.8\u00a0Mutations","rendered":"5.8\u00a0Mutations"},"content":{"raw":"&nbsp;\r\n\r\n[caption id=\"attachment_2380\" align=\"aligncenter\" width=\"400\"]<img class=\"wp-image-2380\" src=\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2019\/06\/11027734365_3b6c9ec284_o-scaled-3.jpg\" alt=\"\" width=\"400\" height=\"264\" \/> <em>Figure 5.8.1 Teenage Mutant Ninja Turtles Cosplay: Raphael and Michelangelo. <\/em>[\/caption]\r\n\r\n<span style=\"font-size: 1.602em; font-weight: bold;\">Mutant Cosplay<\/span>\r\n\r\nYou probably recognize these costumed comic fans in Figure 5.8.1 as two of the four Teenage Mutant Ninja Turtles. Can a mutation really turn a reptile into an anthropomorphic superhero? Of course not \u2014 but mutations <em>can<\/em> often result in other drastic (but more realistic) changes in living things.\r\n<div>\r\n<h1>What Are Mutations?<\/h1>\r\n<\/div>\r\n<strong>[pb_glossary id=\"2381\"]Mutations[\/pb_glossary]<\/strong>\u00a0are random changes in the sequence of bases in\u00a0[pb_glossary id=\"277\"]DNA[\/pb_glossary]\u00a0or\u00a0[pb_glossary id=\"519\"]RNA[\/pb_glossary]. The word\u00a0<em>mutation<\/em>\u00a0may make you think of the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Teenage_Mutant_Ninja_Turtles\">Ninja\u00a0Turtles<\/a>, but that's a misrepresentation of how most mutations work. First of all,\u00a0<em>everyone<\/em>\u00a0has mutations. In fact, most people have dozens (or even hundreds!) of mutations in their\u00a0DNA. Secondly, from an evolutionary perspective, mutations are essential. They are needed for evolution to occur because they are the ultimate source of all new\u00a0genetic variation\u00a0in any\u00a0[pb_glossary id=\"5815\"]species[\/pb_glossary].\r\n<div>\r\n<h1>Causes of Mutations<\/h1>\r\n<\/div>\r\nMutations have many possible causes. Some mutations seem to happen spontaneously, without any outside influence. They occur when errors are made during\u00a0DNA\u00a0replication or during the\u00a0transcription\u00a0phase of\u00a0protein synthesis. Other mutations are caused by environmental factors. Anything in\u00a0the environment\u00a0that can cause a mutation is known as a\u00a0<strong>[pb_glossary id=\"2382\"]mutagen[\/pb_glossary]<\/strong>. Examples of mutagens are shown in the figure\u00a0below.\r\n\r\n[caption id=\"attachment_2383\" align=\"aligncenter\" width=\"899\"]<img class=\"wp-image-2383\" src=\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/Mutagens-2.png\" alt=\"Examples of Radiation, chemicals and infectious agents: An mage of a sun icon and hand x-ray for UV and x-ray radiation; a picture of hands holding a cigarrette and a vape, 3 smokies on a grill (nitrates\/ nitrites and mutagenic BBQ chemicals) and a stylized image of a woman in a green acne face mask with benzoyl peroxide to represent chemicals. To represent infectious agents: an orange spherical virus as human papillomavirus (HPV) and a purple spirilla bacterium with flagella for Helicobacter Pylori - a bacteria spread through contaminated food.\" width=\"899\" height=\"697\" \/> <em>Figure 5.8.2 Examples of Mutagens. Types of mutagens include radiation, chemicals, and infectious agents. Do you know of other examples of each type of mutagen shown here?<\/em>[\/caption]\r\n\r\n<div>\r\n\r\n&nbsp;\r\n\r\n<\/div>\r\n<span style=\"font-size: 1.602em; font-weight: bold;\">Types of Mutations<\/span>\r\n\r\nMutations come in a variety of types. Two major categories of mutations are germline mutations and somatic mutations.\r\n<ul>\r\n \t<li><strong>[pb_glossary id=\"5575\"]Germline mutations[\/pb_glossary] <\/strong>occur in gametes (the sex cells), such as eggs and\u00a0sperm. These mutations are especially significant because they can be transmitted to offspring, causing every cell in the offspring\u00a0to\u00a0carry\u00a0those\u00a0mutations.<\/li>\r\n \t<li><strong>[pb_glossary id=\"5639\"]Somatic mutations[\/pb_glossary] <\/strong>occur in other\u00a0cells\u00a0of the body. These mutations may have little effect on the organism, because they are confined to just one cell and its daughter cells. Somatic mutations cannot be passed on to offspring.<\/li>\r\n<\/ul>\r\nMutations also differ in the way that the genetic material is changed. Mutations may change an entire chromosome, or they may alter just one or a few nucleotides.\r\n<h2>Chromosomal Alterations<\/h2>\r\n<strong>[pb_glossary id=\"2388\"]Chromosomal alterations[\/pb_glossary]<\/strong>\u00a0are mutations that change chromosome structure. They occur when a section of a chromosome breaks off and rejoins incorrectly, or otherwise does not rejoin at all. Possible ways in which these mutations can occur are illustrated in the figure\u00a0below.\u00a0Chromosomal alterations are very serious. They often result in the death of the organism in which they occur. If the organism survives, it may be affected in multiple ways. An example of a human disease caused by a chromosomal duplication is <a href=\"https:\/\/en.wikipedia.org\/wiki\/Charcot%E2%80%93Marie%E2%80%93Tooth_disease\">Charcot-Marie-Tooth disease type 1 (CMT1)<\/a>.\u00a0It is characterized by muscle weakness,\u00a0as well as\u00a0loss of muscle tissue and sensation. The most common cause of CMT1 is a duplication\u00a0of\u00a0part of\u00a0chromosome 17.\r\n\r\n&nbsp;\r\n\r\n[caption id=\"attachment_2387\" align=\"aligncenter\" width=\"434\"]<img class=\"wp-image-2387 size-full\" src=\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/Chromosomenmutationen-2.png\" alt=\"\" width=\"434\" height=\"487\" \/> <em>Figure 5.8.3 Chromosomal alterations are major changes in the genetic material.<\/em>[\/caption]\r\n\r\n<div>\r\n\r\n<span style=\"font-size: 1.424em; font-weight: bold;\">Point Mutations<\/span>\r\n\r\n<\/div>\r\nA\u00a0<strong>[pb_glossary id=\"2389\"]point mutation[\/pb_glossary]<\/strong> is a change in a single nucleotide in DNA. This type of mutation is usually less serious than a chromosomal alteration. An example of a point mutation is a mutation that changes the codon UUU to the codon UCU. Point mutations can be silent, missense, or nonsense mutations, as described in Table 5.8.1. The effects of point mutations depend on how they change the genetic code.\r\n<table style=\"height: 101px; width: 100%;\"><caption>Table 5.8.1: The Effects of Point Mutations<\/caption>\r\n<thead>\r\n<tr style=\"height: 14px;\">\r\n<th scope=\"col\">Type<\/th>\r\n<th scope=\"col\">Description<\/th>\r\n<th scope=\"col\">Example<\/th>\r\n<th scope=\"col\">Effect<\/th>\r\n<\/tr>\r\n<\/thead>\r\n<tbody>\r\n<tr style=\"height: 29px;\">\r\n<td>Silent<\/td>\r\n<td>mutated codon codes for the same [pb_glossary id=\"5707\"]amino\u00a0acid[\/pb_glossary]<\/td>\r\n<td>CAA (glutamine) \u2192 CAG (glutamine)<\/td>\r\n<td>none<\/td>\r\n<\/tr>\r\n<tr style=\"height: 29px;\">\r\n<td>Missense<\/td>\r\n<td>mutated codon codes for a different amino\u00a0acid<\/td>\r\n<td>CAA (glutamine) \u2192 CCA (proline)<\/td>\r\n<td>variable<\/td>\r\n<\/tr>\r\n<tr style=\"height: 29px;\">\r\n<td>Nonsense<\/td>\r\n<td>mutated codon is a premature stop codon<\/td>\r\n<td>CAA (glutamine) \u2192 UAA (stop) usually<\/td>\r\n<td>serious<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n<h2>Frameshift Mutations<\/h2>\r\nA\u00a0<strong>[pb_glossary id=\"6019\"]frameshift mutation[\/pb_glossary]<\/strong>\u00a0is a deletion or insertion of one or more nucleotides, changing the [pb_glossary id=\"5555\"]reading frame[\/pb_glossary] of the\u00a0base\u00a0sequence. Deletions remove nucleotides, and insertions add nucleotides. Consider the following sequence of bases in\u00a0RNA:\r\n\r\n<strong>AUG-AAU-ACG-GCU = start-asparagine-threonine-alanine<\/strong>\r\n\r\nNow, assume that an insertion occurs in this sequence. Let\u2019s say an\u00a0<strong>A <\/strong>nucleotide is inserted after the start codon\u00a0<strong>AUG.<\/strong>\u00a0The sequence of bases becomes:\r\n\r\n<strong>AUG-AA<span style=\"color: #800000; background-color: #ffff99;\">A<\/span>-UAC-GGC-U = start-lysine-tyrosine-glycine<\/strong>\r\n\r\nEven though the rest of the sequence is unchanged, this insertion changes the reading frame and, therefore, all of the codons that follow it. As this example shows, a frameshift mutation can dramatically change how the codons in mRNA are read. This can have a drastic effect on the\u00a0[pb_glossary id=\"5813\"]protein[\/pb_glossary]\u00a0product.\r\n<div>\r\n<h1>Effects of Mutations<\/h1>\r\n<\/div>\r\nThe majority of [pb_glossary id=\"2381\"]mutations[\/pb_glossary]\u00a0have neither negative nor positive effects on the organism in which they occur. These mutations are called neutral mutations. Examples include silent point mutations, which are neutral because they do not change the\u00a0amino acids\u00a0in the\u00a0proteins\u00a0they encode.\r\n\r\nMany other mutations have no effects on the organism because they are repaired before\u00a0protein synthesis\u00a0occurs.\u00a0Cells\u00a0have multiple repair mechanisms to fix mutations in DNA.\r\n<h2>Beneficial Mutations<\/h2>\r\nSome mutations \u2014 known as\u00a0<strong>beneficial mutations<\/strong>\u00a0\u2014\u00a0have a positive effect on the organism in which they occur. They generally code for new versions of\u00a0proteins\u00a0that help organisms adapt to their environment. If they increase an organism\u2019s chances of surviving or reproducing, the mutations are likely to become more common over time. There are several well-known examples of beneficial mutations. Here are two such examples:\r\n<ol>\r\n \t<li>Mutations have occurred in\u00a0bacteria\u00a0that allow the bacteria to survive in the presence of antibiotic drugs, leading to the evolution of antibiotic-resistant strains of bacteria.<\/li>\r\n \t<li>A unique mutation is found in people in <a href=\"https:\/\/en.wikipedia.org\/wiki\/Limone_sul_Garda\">Limone<\/a>,\u00a0 a small town in Italy. The mutation protects them from developing atherosclerosis, which is the dangerous buildup of fatty materials in blood vessels despite a high-fat diet. The individual in which this mutation first appeared has even been identified and many of his descendants carry this gene.<\/li>\r\n<\/ol>\r\n<h2>Harmful Mutations<\/h2>\r\nImagine making a random change in a complicated\u00a0machine, such as a car engine.\u00a0There is a chance that the random change would result in a car that does not run well \u2014 or perhaps does not run at all. By the same token, a random change in a gene's DNA may result in the production of a\u00a0protein\u00a0that does not function normally... or may not function at all.\u00a0Such mutations are likely to be harmful.\u00a0<strong>Harmful mutations<\/strong>\u00a0may cause\u00a0genetic disorders\u00a0or\u00a0[pb_glossary id=\"5605\"]cancer[\/pb_glossary].\r\n<ul>\r\n \t<li>A <strong>genetic disorder<\/strong> is a disease, syndrome, or other abnormal condition caused by a mutation in one or more genes, or by a chromosomal alteration. An example of a genetic disorder is <a href=\"https:\/\/en.wikipedia.org\/wiki\/Cystic_fibrosis\">cystic fibrosis<\/a>. A mutation in a single gene causes the body to produce thick, sticky mucus that clogs the lungs and blocks ducts in digestive organs.<\/li>\r\n \t<li><strong>[pb_glossary id=\"5605\"]Cancer[\/pb_glossary] <\/strong>is a disease in which\u00a0cells\u00a0grow out of control and form abnormal masses of cells (called tumors). It is generally caused by mutations in genes that regulate the\u00a0[pb_glossary id=\"5643\"]cell cycle[\/pb_glossary]. Because of the mutations, cells with damaged [pb_glossary id=\"277\"]DNA[\/pb_glossary] are allowed to divide without restriction.<\/li>\r\n<\/ul>\r\n<div>\r\n<h1>Feature: My\u00a0Human Body<\/h1>\r\n<\/div>\r\nInherited mutations are thought to play a role in roughly five to ten per cent of all cancers. Specific mutations that cause many of the known hereditary cancers have been identified. Most of the mutations occur in genes that control the growth of cells or the repair of damaged DNA.\r\n\r\nGenetic testing can be done to determine whether individuals have inherited specific cancer-causing mutations. Some of the most common inherited cancers for which genetic testing is available include hereditary <a href=\"https:\/\/en.wikipedia.org\/wiki\/Breast_cancer\">breast<\/a> and <a href=\"https:\/\/en.wikipedia.org\/wiki\/Ovarian_cancer\">ovarian\u00a0cancer<\/a>, caused by mutations in genes\u00a0called\u00a0<a href=\"https:\/\/en.wikipedia.org\/wiki\/BRCA_mutation\">BRCA1 and BRCA2<\/a>. Besides breast and ovarian cancers, mutations in these genes may also cause pancreatic and prostate cancers.\u00a0Genetic testing is generally done on a small sample of body fluid or tissue, such as\u00a0blood, saliva, or skin cells. The sample is analyzed by a lab that specializes in genetic testing, and it usually takes at least a few weeks to get the test results.\r\n\r\nShould you get genetic testing to find out whether you have inherited a cancer-causing mutation? Such testing is not done routinely just to screen patients for risk of cancer. Instead, the tests are generally done only when the following three criteria are met:\r\n<ol>\r\n \t<li>The test can determine definitively whether a specific gene mutation is present. This is the case with the BRCA1 and BRCA2 gene mutations, for example.<\/li>\r\n \t<li>The test results would be useful to help guide future medical care. For example, if you found out you had a mutation in the BRCA1 or BRCA2 gene, you might get more frequent breast and ovarian cancer screenings than are generally recommended.<\/li>\r\n \t<li>You have a personal or family history that suggests you are at risk of an inherited cancer.<\/li>\r\n<\/ol>\r\nCriterion number 3 is based, in turn, on such factors as:\r\n<ul>\r\n \t<li>Diagnosis of cancer at an unusually young age.<\/li>\r\n \t<li>Several different cancers occurring independently in the same individual.<\/li>\r\n \t<li>Several close genetic relatives having the same type of cancer (such as a maternal grandmother, mother, and sister all having breast cancer).<\/li>\r\n \t<li>Cancer occurring in both organs in a set of paired organs (such as both kidneys or both breasts).<\/li>\r\n<\/ul>\r\nIf you meet the criteria for genetic testing and are advised to undergo it, genetic counseling is highly recommended. A genetic counselor can help you understand what the results mean and how to make use of them to reduce your risk of developing cancer. For example, a positive test result that shows the presence of a mutation may not\u00a0<em>necessarily<\/em>\u00a0mean that you will develop cancer. It may depend on whether the gene is located on an autosome or sex chromosome, and whether the mutation is dominant or recessive. Lifestyle factors may also play a role in cancer risk even for hereditary cancers. Early detection can often be life saving if cancer does develop. Genetic counseling can also help you assess the chances that any children you may have will inherit the mutation.\r\n<div>\r\n<div class=\"textbox textbox--key-takeaways\"><header class=\"textbox__header\">\r\n<h1 class=\"textbox__title\"><span style=\"color: #ffffff;\">5.8 Summary<\/span><\/h1>\r\n<\/header>\r\n<div class=\"textbox__content\">\r\n<ul>\r\n \t<li>[pb_glossary id=\"2381\"]Mutations[\/pb_glossary] are random changes in the sequence of bases in [pb_glossary id=\"277\"]DNA[\/pb_glossary] or\u00a0[pb_glossary id=\"519\"]RNA[\/pb_glossary]. Most people have multiple mutations in their DNA without ill effects. Mutations are the ultimate source of all new\u00a0genetic variation\u00a0in any\u00a0species.<\/li>\r\n \t<li>Mutations may happen spontaneously during [pb_glossary id=\"5559\"]DNA replication[\/pb_glossary] or\u00a0[pb_glossary id=\"2241\"]transcription[\/pb_glossary]. Other mutations are caused by environmental factors called [pb_glossary id=\"2382\"]mutagens[\/pb_glossary]. Mutagens include radiation, certain chemicals, and some infectious agents.<\/li>\r\n \t<li>[pb_glossary id=\"5575\"]Germline mutations[\/pb_glossary] occur in gametes and may be passed onto offspring. Every cell in the offspring will then have the mutation. [pb_glossary id=\"5639\"]Somatic mutations[\/pb_glossary] occur in cells other than gametes and are confined to just one cell and its daughter cells. These mutations cannot be passed on to offspring.<\/li>\r\n \t<li>[pb_glossary id=\"2388\"]Chromosomal alterations[\/pb_glossary] are mutations that change chromosome structure and usually affect the organism in multiple ways.\u00a0Charcot-Marie-Tooth disease type 1\u00a0is an example of a chromosomal alteration in humans.<\/li>\r\n \t<li>[pb_glossary id=\"2389\"]Point mutations[\/pb_glossary] are changes in a single nucleotide. The effects of point mutations depend on how they change the\u00a0genetic code\u00a0and may range from no effects to very serious effects.<\/li>\r\n \t<li>[pb_glossary id=\"2392\"]Frameshift mutations[\/pb_glossary] change the reading frame of the\u00a0genetic code\u00a0and are likely to have a drastic effect on the encoded\u00a0protein.<\/li>\r\n \t<li>Many mutations are neutral and have no effect on the organism in which they occur. Some mutations are beneficial and improve fitness. An example is a mutation that confers antibiotic\u00a0resistance\u00a0in\u00a0bacteria. Other mutations are harmful and decrease fitness, such as the mutations that cause\u00a0genetic disorders\u00a0or [pb_glossary id=\"5605\"]cancers[\/pb_glossary].<\/li>\r\n<\/ul>\r\n<\/div>\r\n<\/div>\r\n<div class=\"textbox textbox--exercises\"><header class=\"textbox__header\">\r\n<h1 class=\"textbox__title\"><span style=\"color: #ffffff;\">5.8 Review Question<\/span><\/h1>\r\n<\/header>\r\n<div class=\"textbox__content\">\r\n<ol>\r\n \t<li>Define mutation.<\/li>\r\n \t<li>Identify causes of mutation.<\/li>\r\n \t<li>Compare and contrast germline and somatic mutations.<\/li>\r\n \t<li>Describe chromosomal alterations, point mutations, and frameshift mutations. Identify the potential effects of each type of mutation.<\/li>\r\n \t<li>Why\u00a0do many mutations have neutral effects?<\/li>\r\n \t<li>Give one\u00a0example of a beneficial mutation and one\u00a0example of a harmful mutation.<\/li>\r\n \t<li>[h5p id=\"502\"]<\/li>\r\n \t<li>Why do you think that exposure to mutagens (such as cigarette smoke) can cause cancer?<\/li>\r\n \t<li>Explain why the insertion or deletion of a single nucleotide can cause a frameshift mutation.<\/li>\r\n \t<li>Compare and contrast missense and nonsense mutations.<\/li>\r\n \t<li>Explain why mutations are important to\u00a0evolution.<\/li>\r\n<\/ol>\r\n&nbsp;\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div class=\"textbox textbox--examples\"><header class=\"textbox__header\">\r\n<h1 class=\"textbox__title\"><span style=\"color: #ffffff;\">5.8 Explore More<\/span><\/h1>\r\n<\/header>\r\n<div class=\"textbox__content\">\r\n\r\nhttps:\/\/www.youtube.com\/watch?time_continue=51&amp;v=PQjL4ZDuq2o&amp;feature=emb_logo\r\n<p style=\"text-align: center;\">How Radiation Changes Your DNA, Seeker, 2016.<\/p>\r\nhttps:\/\/www.youtube.com\/watch?v=z9HIYjRRaDE&amp;t=93s\r\n<p style=\"text-align: center;\">Where do genes come from? - Carl Zimmer, TED-Ed, 2014.<\/p>\r\nhttps:\/\/www.youtube.com\/watch?v=a63t8r70QN0&amp;feature=youtu.be\r\n<p style=\"text-align: center;\">What you should know about vaping and e-cigarettes | Suchitra Krishnan-Sarin,\r\nTED, 2019.<\/p>\r\n\r\n<\/div>\r\n<\/div>\r\n<h2>Attributions<\/h2>\r\n<strong>Figure 5.8.1<\/strong>\r\n\r\n<a href=\"https:\/\/www.flickr.com\/photos\/patloika\/11027734365\/in\/photostream\/\" rel=\"cc:attributionURL\">Ninja Turtles<\/a>\u00a0by\u00a0<a href=\"https:\/\/www.flickr.com\/photos\/patloika\/\" rel=\"dc:creator\">Pat Loika<\/a> on <a href=\"https:\/\/www.flickr.com\/\">Flickr<\/a> is used under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/\">CC BY 2.0 <\/a>(https:\/\/creativecommons.org\/licenses\/by\/2.0\/<a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\" rel=\"license\">)<\/a> license.\r\n\r\n<strong>Figure 5.8.2<\/strong>\r\n<div>Examples of Mutagens by Christine MIller is used under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/\">CC BY SA 4.0<\/a> (https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/) license.\r\nSeparate images are all in public domain or CC licensed:<\/div>\r\n<ul>\r\n \t<li><a style=\"font-size: 1em;\" href=\"https:\/\/pixabay.com\/illustrations\/beauty-treatment-face-mask-girl-163540\/\">Beauty treatment face mask<\/a><span style=\"font-size: 1em;\"> by <\/span><a style=\"font-size: 1em;\" href=\"https:\/\/pixabay.com\/users\/no-longer-here-19203\/\">no-longer-here<\/a><span style=\"font-size: 1em;\"> on <\/span><a style=\"font-size: 1em;\" href=\"https:\/\/pixabay.com\/\">Pixabay<\/a><span style=\"font-size: 1em;\"> is used under the <\/span><a style=\"font-size: 1em;\" href=\"https:\/\/pixabay.com\/service\/license\/\">Pixabay License<\/a><span style=\"font-size: 1em;\"> (https:\/\/pixabay.com\/service\/license\/).<\/span><\/li>\r\n \t<li><a href=\"https:\/\/www.flickr.com\/photos\/ajc1\/277161177\">HPV<\/a> by <a class=\"owner-name truncate\" title=\"Go to AJC1's photostream\" href=\"https:\/\/www.flickr.com\/photos\/ajc1\/\" data-track=\"attributionNameClick\">AJC1<\/a> on <a href=\"https:\/\/www.flickr.com\/\">Flickr<\/a> is used under a\u00a0<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/2.0\/\">CC BY-NC 2.0<\/a> (https:\/\/creativecommons.org\/licenses\/by-nc\/2.0\/) license.<\/li>\r\n \t<li><span style=\"background-color: #ffffff;\"><a style=\"background-color: #ffffff;\" href=\"https:\/\/www.flickr.com\/search\/?user_id=47353092%40N00&amp;view_all=1&amp;text=bacteria\">H Pylori<\/a> by <a class=\"owner-name truncate\" style=\"background-color: #ffffff;\" title=\"Go to AJC1's photostream\" href=\"https:\/\/www.flickr.com\/photos\/ajc1\/\" data-track=\"attributionNameClick\">AJC1<\/a> on <a style=\"background-color: #ffffff;\" href=\"https:\/\/www.flickr.com\/\">Flickr<\/a> is used under a <a style=\"background-color: #ffffff;\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/2.0\/\">CC BY-NC 2.0<\/a> (https:\/\/creativecommons.org\/licenses\/by-nc\/2.0\/) license.\u00a0<\/span><\/li>\r\n \t<li><span style=\"font-size: 1em;\"><a href=\"https:\/\/www.flickr.com\/photos\/vaping360\/18539459466\">Vape and Cigarette<\/a> by <a class=\"owner-name truncate\" title=\"Go to Vaping360's photostream\" href=\"https:\/\/www.flickr.com\/photos\/vaping360\/\" data-track=\"attributionNameClick\">Vaping360<\/a><\/span> on <a href=\"https:\/\/www.flickr.com\/\">Flickr<\/a> is used under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/\">CC BY 2.0<\/a> (https:\/\/creativecommons.org\/licenses\/by\/2.0\/) license.<\/li>\r\n \t<li><span style=\"font-size: 1em;\"><a href=\"https:\/\/commons.wikimedia.org\/w\/index.php?curid=12143891\">Hand X-Ray<\/a> by<\/span> <a title=\"User:Hellerhoff\" href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Hellerhoff\">Hellerhoff<\/a> on Wikimedia Commons - <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/deed.en\">CC BY-SA 3.0 <\/a>(https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/deed.en) license.<\/li>\r\n \t<li><a href=\"https:\/\/www.pxfuel.com\/en\/free-photo-obmsy\"><span style=\"font-size: 1em;\">Hot dogs<\/span><\/a><span style=\"font-size: 1em;\"> by unknown on <a href=\"https:\/\/www.pxfuel.com\/\">PxFuel<\/a> is used under the <a href=\"https:\/\/www.pxfuel.com\/terms-of-use\">Pxfuel Terms <\/a>(https:\/\/www.pxfuel.com\/terms-of-use).<\/span><\/li>\r\n \t<li>Sunshine face is clipart.<\/li>\r\n<\/ul>\r\n<strong>Figure 5.8.3<\/strong>\r\n\r\n<span style=\"text-align: initial; font-size: 1em; color: #373d3f;\">Scheme of possible chromosome mutations\/ <a href=\"https:\/\/commons.wikimedia.org\/w\/index.php?curid=1413589\">Chromosomenmutationen<\/a> by unknown on Wikimedia Commons is adapted from N<\/span><span style=\"color: #373d3f; font-size: 1em;\">IH<\/span><span style=\"text-align: initial; font-size: 1em; color: #373d3f;\">'s <a href=\"https:\/\/www.genome.gov\/genetics-glossary\/Mutation\">Talking Glossary of Genetics<\/a>. [Changes as described by <a href=\"https:\/\/de.wikipedia.org\/wiki\/Benutzer:Dietzel65\">de:user:Dietzel65<\/a>]. Further use and adapation (text translated to English) by\u00a0<\/span><span style=\"text-align: initial; font-size: 1em; color: #373d3f;\">Christine Miller as image is in the <a style=\"text-align: initial; font-size: 1em;\" href=\"https:\/\/creativecommons.org\/publicdomain\/mark\/1.0\/\" rel=\"license\">public domain<\/a> (https:\/\/en.wikipedia.org\/wiki\/Public_domain).<\/span>\r\n\r\n&nbsp;\r\n\r\n<span style=\"font-size: 1.424em; font-weight: bold;\">References<\/span>\r\n<p class=\"hanging-indent\">Seeker. (2016, April 23). How radiation changes your DNA. YouTube. https:\/\/www.youtube.com\/watch?v=PQjL4ZDuq2o&amp;feature=youtu.be<\/p>\r\n<p class=\"hanging-indent\">TED. (2019, June 5). What you should know about vaping and e-cigarettes | Suchitra Krishnan-Sarin. YouTube. https:\/\/www.youtube.com\/watch?v=a63t8r70QN0&amp;feature=youtu.be<\/p>\r\n<p class=\"hanging-indent\">TED-Ed. (2014, September 22). Where do genes come from? - Carl Zimmer. YouTube. https:\/\/www.youtube.com\/watch?v=z9HIYjRRaDE&amp;feature=youtu.be<\/p>\r\n<p class=\"hanging-indent\">Wikipedia contributors. (2020, July 6). Breast cancer. In Wikipedia.\u00a0 https:\/\/en.wikipedia.org\/w\/index.php?title=Breast_cancer&amp;oldid=966366739<\/p>\r\n<p class=\"hanging-indent\">Wikipedia contributors. (2020, July 9). Charcot\u2013Marie\u2013Tooth disease. In <em>Wikipedia<\/em>. https:\/\/en.wikipedia.org\/w\/index.php?title=Charcot%E2%80%93Marie%E2%80%93Tooth_disease&amp;oldid=966912915<\/p>\r\n<p class=\"hanging-indent\">Wikipedia contributors. (2020, July 7). Cystic fibrosis. In <em>Wikipedia<\/em>.\u00a0 https:\/\/en.wikipedia.org\/w\/index.php?title=Cystic_fibrosis&amp;oldid=966566921<\/p>\r\n<p class=\"hanging-indent\">Wikipedia contributors. (2020, June 4). Limone sul Garda. In\u00a0<i>Wikipedia. <\/i>https:\/\/en.wikipedia.org\/w\/index.php?title=Limone_sul_Garda&amp;oldid=960771991<\/p>\r\n<p class=\"hanging-indent\">Wikipedia contributors. (2020, June 23). Ovarian cancer. In <em>Wikipedia<\/em>.\u00a0 https:\/\/en.wikipedia.org\/w\/index.php?title=Ovarian_cancer&amp;oldid=964157192<\/p>\r\n<p class=\"hanging-indent\">Wikipedia contributors. (2020, May 7). BRCA mutation. In <em>Wikipedia<\/em>. https:\/\/en.wikipedia.org\/w\/index.php?title=BRCA_mutation&amp;oldid=955463902<\/p>\r\n<p class=\"hanging-indent\">Wikipedia contributors. (2020, July 10). Teenage Mutant Ninja Turtles. In <em>Wikipedia<\/em>. https:\/\/en.wikipedia.org\/w\/index.php?title=Teenage_Mutant_Ninja_Turtles&amp;oldid=967030468<\/p>\r\n&nbsp;","rendered":"<p>&nbsp;<\/p>\n<figure id=\"attachment_2380\" aria-describedby=\"caption-attachment-2380\" style=\"width: 400px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2380\" src=\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2019\/06\/11027734365_3b6c9ec284_o-scaled-3.jpg\" alt=\"\" width=\"400\" height=\"264\" \/><figcaption id=\"caption-attachment-2380\" class=\"wp-caption-text\"><em>Figure 5.8.1 Teenage Mutant Ninja Turtles Cosplay: Raphael and Michelangelo. <\/em><\/figcaption><\/figure>\n<p><span style=\"font-size: 1.602em; font-weight: bold;\">Mutant Cosplay<\/span><\/p>\n<p>You probably recognize these costumed comic fans in Figure 5.8.1 as two of the four Teenage Mutant Ninja Turtles. Can a mutation really turn a reptile into an anthropomorphic superhero? Of course not \u2014 but mutations <em>can<\/em> often result in other drastic (but more realistic) changes in living things.<\/p>\n<div>\n<h1>What Are Mutations?<\/h1>\n<\/div>\n<p><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4549_2381\">Mutations<\/a><\/strong>\u00a0are random changes in the sequence of bases in\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4549_277\">DNA<\/a>\u00a0or\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4549_519\">RNA<\/a>. The word\u00a0<em>mutation<\/em>\u00a0may make you think of the <a href=\"https:\/\/en.wikipedia.org\/wiki\/Teenage_Mutant_Ninja_Turtles\">Ninja\u00a0Turtles<\/a>, but that&#8217;s a misrepresentation of how most mutations work. First of all,\u00a0<em>everyone<\/em>\u00a0has mutations. In fact, most people have dozens (or even hundreds!) of mutations in their\u00a0DNA. Secondly, from an evolutionary perspective, mutations are essential. They are needed for evolution to occur because they are the ultimate source of all new\u00a0genetic variation\u00a0in any\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4549_5815\">species<\/a>.<\/p>\n<div>\n<h1>Causes of Mutations<\/h1>\n<\/div>\n<p>Mutations have many possible causes. Some mutations seem to happen spontaneously, without any outside influence. They occur when errors are made during\u00a0DNA\u00a0replication or during the\u00a0transcription\u00a0phase of\u00a0protein synthesis. Other mutations are caused by environmental factors. Anything in\u00a0the environment\u00a0that can cause a mutation is known as a\u00a0<strong>mutagen<\/strong>. Examples of mutagens are shown in the figure\u00a0below.<\/p>\n<figure id=\"attachment_2383\" aria-describedby=\"caption-attachment-2383\" style=\"width: 899px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2383\" src=\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/Mutagens-2.png\" alt=\"Examples of Radiation, chemicals and infectious agents: An mage of a sun icon and hand x-ray for UV and x-ray radiation; a picture of hands holding a cigarrette and a vape, 3 smokies on a grill (nitrates\/ nitrites and mutagenic BBQ chemicals) and a stylized image of a woman in a green acne face mask with benzoyl peroxide to represent chemicals. To represent infectious agents: an orange spherical virus as human papillomavirus (HPV) and a purple spirilla bacterium with flagella for Helicobacter Pylori - a bacteria spread through contaminated food.\" width=\"899\" height=\"697\" \/><figcaption id=\"caption-attachment-2383\" class=\"wp-caption-text\"><em>Figure 5.8.2 Examples of Mutagens. Types of mutagens include radiation, chemicals, and infectious agents. Do you know of other examples of each type of mutagen shown here?<\/em><\/figcaption><\/figure>\n<div>\n<p>&nbsp;<\/p>\n<\/div>\n<p><span style=\"font-size: 1.602em; font-weight: bold;\">Types of Mutations<\/span><\/p>\n<p>Mutations come in a variety of types. Two major categories of mutations are germline mutations and somatic mutations.<\/p>\n<ul>\n<li><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4549_5575\">Germline mutations<\/a> <\/strong>occur in gametes (the sex cells), such as eggs and\u00a0sperm. These mutations are especially significant because they can be transmitted to offspring, causing every cell in the offspring\u00a0to\u00a0carry\u00a0those\u00a0mutations.<\/li>\n<li><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4549_5639\">Somatic mutations<\/a> <\/strong>occur in other\u00a0cells\u00a0of the body. These mutations may have little effect on the organism, because they are confined to just one cell and its daughter cells. Somatic mutations cannot be passed on to offspring.<\/li>\n<\/ul>\n<p>Mutations also differ in the way that the genetic material is changed. Mutations may change an entire chromosome, or they may alter just one or a few nucleotides.<\/p>\n<h2>Chromosomal Alterations<\/h2>\n<p><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4549_2388\">Chromosomal alterations<\/a><\/strong>\u00a0are mutations that change chromosome structure. They occur when a section of a chromosome breaks off and rejoins incorrectly, or otherwise does not rejoin at all. Possible ways in which these mutations can occur are illustrated in the figure\u00a0below.\u00a0Chromosomal alterations are very serious. They often result in the death of the organism in which they occur. If the organism survives, it may be affected in multiple ways. An example of a human disease caused by a chromosomal duplication is <a href=\"https:\/\/en.wikipedia.org\/wiki\/Charcot%E2%80%93Marie%E2%80%93Tooth_disease\">Charcot-Marie-Tooth disease type 1 (CMT1)<\/a>.\u00a0It is characterized by muscle weakness,\u00a0as well as\u00a0loss of muscle tissue and sensation. The most common cause of CMT1 is a duplication\u00a0of\u00a0part of\u00a0chromosome 17.<\/p>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2387\" aria-describedby=\"caption-attachment-2387\" style=\"width: 434px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2387 size-full\" src=\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/Chromosomenmutationen-2.png\" alt=\"\" width=\"434\" height=\"487\" \/><figcaption id=\"caption-attachment-2387\" class=\"wp-caption-text\"><em>Figure 5.8.3 Chromosomal alterations are major changes in the genetic material.<\/em><\/figcaption><\/figure>\n<div>\n<p><span style=\"font-size: 1.424em; font-weight: bold;\">Point Mutations<\/span><\/p>\n<\/div>\n<p>A\u00a0<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4549_2389\">point mutation<\/a><\/strong> is a change in a single nucleotide in DNA. This type of mutation is usually less serious than a chromosomal alteration. An example of a point mutation is a mutation that changes the codon UUU to the codon UCU. Point mutations can be silent, missense, or nonsense mutations, as described in Table 5.8.1. The effects of point mutations depend on how they change the genetic code.<\/p>\n<table style=\"height: 101px; width: 100%;\">\n<caption>Table 5.8.1: The Effects of Point Mutations<\/caption>\n<thead>\n<tr style=\"height: 14px;\">\n<th scope=\"col\">Type<\/th>\n<th scope=\"col\">Description<\/th>\n<th scope=\"col\">Example<\/th>\n<th scope=\"col\">Effect<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr style=\"height: 29px;\">\n<td>Silent<\/td>\n<td>mutated codon codes for the same <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4549_5707\">amino\u00a0acid<\/a><\/td>\n<td>CAA (glutamine) \u2192 CAG (glutamine)<\/td>\n<td>none<\/td>\n<\/tr>\n<tr style=\"height: 29px;\">\n<td>Missense<\/td>\n<td>mutated codon codes for a different amino\u00a0acid<\/td>\n<td>CAA (glutamine) \u2192 CCA (proline)<\/td>\n<td>variable<\/td>\n<\/tr>\n<tr style=\"height: 29px;\">\n<td>Nonsense<\/td>\n<td>mutated codon is a premature stop codon<\/td>\n<td>CAA (glutamine) \u2192 UAA (stop) usually<\/td>\n<td>serious<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h2>Frameshift Mutations<\/h2>\n<p>A\u00a0<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4549_6019\">frameshift mutation<\/a><\/strong>\u00a0is a deletion or insertion of one or more nucleotides, changing the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4549_5555\">reading frame<\/a> of the\u00a0base\u00a0sequence. Deletions remove nucleotides, and insertions add nucleotides. Consider the following sequence of bases in\u00a0RNA:<\/p>\n<p><strong>AUG-AAU-ACG-GCU = start-asparagine-threonine-alanine<\/strong><\/p>\n<p>Now, assume that an insertion occurs in this sequence. Let\u2019s say an\u00a0<strong>A <\/strong>nucleotide is inserted after the start codon\u00a0<strong>AUG.<\/strong>\u00a0The sequence of bases becomes:<\/p>\n<p><strong>AUG-AA<span style=\"color: #800000; background-color: #ffff99;\">A<\/span>-UAC-GGC-U = start-lysine-tyrosine-glycine<\/strong><\/p>\n<p>Even though the rest of the sequence is unchanged, this insertion changes the reading frame and, therefore, all of the codons that follow it. As this example shows, a frameshift mutation can dramatically change how the codons in mRNA are read. This can have a drastic effect on the\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4549_5813\">protein<\/a>\u00a0product.<\/p>\n<div>\n<h1>Effects of Mutations<\/h1>\n<\/div>\n<p>The majority of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4549_2381\">mutations<\/a>\u00a0have neither negative nor positive effects on the organism in which they occur. These mutations are called neutral mutations. Examples include silent point mutations, which are neutral because they do not change the\u00a0amino acids\u00a0in the\u00a0proteins\u00a0they encode.<\/p>\n<p>Many other mutations have no effects on the organism because they are repaired before\u00a0protein synthesis\u00a0occurs.\u00a0Cells\u00a0have multiple repair mechanisms to fix mutations in DNA.<\/p>\n<h2>Beneficial Mutations<\/h2>\n<p>Some mutations \u2014 known as\u00a0<strong>beneficial mutations<\/strong>\u00a0\u2014\u00a0have a positive effect on the organism in which they occur. They generally code for new versions of\u00a0proteins\u00a0that help organisms adapt to their environment. If they increase an organism\u2019s chances of surviving or reproducing, the mutations are likely to become more common over time. There are several well-known examples of beneficial mutations. Here are two such examples:<\/p>\n<ol>\n<li>Mutations have occurred in\u00a0bacteria\u00a0that allow the bacteria to survive in the presence of antibiotic drugs, leading to the evolution of antibiotic-resistant strains of bacteria.<\/li>\n<li>A unique mutation is found in people in <a href=\"https:\/\/en.wikipedia.org\/wiki\/Limone_sul_Garda\">Limone<\/a>,\u00a0 a small town in Italy. The mutation protects them from developing atherosclerosis, which is the dangerous buildup of fatty materials in blood vessels despite a high-fat diet. The individual in which this mutation first appeared has even been identified and many of his descendants carry this gene.<\/li>\n<\/ol>\n<h2>Harmful Mutations<\/h2>\n<p>Imagine making a random change in a complicated\u00a0machine, such as a car engine.\u00a0There is a chance that the random change would result in a car that does not run well \u2014 or perhaps does not run at all. By the same token, a random change in a gene&#8217;s DNA may result in the production of a\u00a0protein\u00a0that does not function normally&#8230; or may not function at all.\u00a0Such mutations are likely to be harmful.\u00a0<strong>Harmful mutations<\/strong>\u00a0may cause\u00a0genetic disorders\u00a0or\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4549_5605\">cancer<\/a>.<\/p>\n<ul>\n<li>A <strong>genetic disorder<\/strong> is a disease, syndrome, or other abnormal condition caused by a mutation in one or more genes, or by a chromosomal alteration. An example of a genetic disorder is <a href=\"https:\/\/en.wikipedia.org\/wiki\/Cystic_fibrosis\">cystic fibrosis<\/a>. A mutation in a single gene causes the body to produce thick, sticky mucus that clogs the lungs and blocks ducts in digestive organs.<\/li>\n<li><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4549_5605\">Cancer<\/a> <\/strong>is a disease in which\u00a0cells\u00a0grow out of control and form abnormal masses of cells (called tumors). It is generally caused by mutations in genes that regulate the\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4549_5643\">cell cycle<\/a>. Because of the mutations, cells with damaged <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4549_277\">DNA<\/a> are allowed to divide without restriction.<\/li>\n<\/ul>\n<div>\n<h1>Feature: My\u00a0Human Body<\/h1>\n<\/div>\n<p>Inherited mutations are thought to play a role in roughly five to ten per cent of all cancers. Specific mutations that cause many of the known hereditary cancers have been identified. Most of the mutations occur in genes that control the growth of cells or the repair of damaged DNA.<\/p>\n<p>Genetic testing can be done to determine whether individuals have inherited specific cancer-causing mutations. Some of the most common inherited cancers for which genetic testing is available include hereditary <a href=\"https:\/\/en.wikipedia.org\/wiki\/Breast_cancer\">breast<\/a> and <a href=\"https:\/\/en.wikipedia.org\/wiki\/Ovarian_cancer\">ovarian\u00a0cancer<\/a>, caused by mutations in genes\u00a0called\u00a0<a href=\"https:\/\/en.wikipedia.org\/wiki\/BRCA_mutation\">BRCA1 and BRCA2<\/a>. Besides breast and ovarian cancers, mutations in these genes may also cause pancreatic and prostate cancers.\u00a0Genetic testing is generally done on a small sample of body fluid or tissue, such as\u00a0blood, saliva, or skin cells. The sample is analyzed by a lab that specializes in genetic testing, and it usually takes at least a few weeks to get the test results.<\/p>\n<p>Should you get genetic testing to find out whether you have inherited a cancer-causing mutation? Such testing is not done routinely just to screen patients for risk of cancer. Instead, the tests are generally done only when the following three criteria are met:<\/p>\n<ol>\n<li>The test can determine definitively whether a specific gene mutation is present. This is the case with the BRCA1 and BRCA2 gene mutations, for example.<\/li>\n<li>The test results would be useful to help guide future medical care. For example, if you found out you had a mutation in the BRCA1 or BRCA2 gene, you might get more frequent breast and ovarian cancer screenings than are generally recommended.<\/li>\n<li>You have a personal or family history that suggests you are at risk of an inherited cancer.<\/li>\n<\/ol>\n<p>Criterion number 3 is based, in turn, on such factors as:<\/p>\n<ul>\n<li>Diagnosis of cancer at an unusually young age.<\/li>\n<li>Several different cancers occurring independently in the same individual.<\/li>\n<li>Several close genetic relatives having the same type of cancer (such as a maternal grandmother, mother, and sister all having breast cancer).<\/li>\n<li>Cancer occurring in both organs in a set of paired organs (such as both kidneys or both breasts).<\/li>\n<\/ul>\n<p>If you meet the criteria for genetic testing and are advised to undergo it, genetic counseling is highly recommended. A genetic counselor can help you understand what the results mean and how to make use of them to reduce your risk of developing cancer. For example, a positive test result that shows the presence of a mutation may not\u00a0<em>necessarily<\/em>\u00a0mean that you will develop cancer. It may depend on whether the gene is located on an autosome or sex chromosome, and whether the mutation is dominant or recessive. Lifestyle factors may also play a role in cancer risk even for hereditary cancers. Early detection can often be life saving if cancer does develop. Genetic counseling can also help you assess the chances that any children you may have will inherit the mutation.<\/p>\n<div>\n<div class=\"textbox textbox--key-takeaways\">\n<header class=\"textbox__header\">\n<h1 class=\"textbox__title\"><span style=\"color: #ffffff;\">5.8 Summary<\/span><\/h1>\n<\/header>\n<div class=\"textbox__content\">\n<ul>\n<li><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4549_2381\">Mutations<\/a> are random changes in the sequence of bases in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4549_277\">DNA<\/a> or\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4549_519\">RNA<\/a>. Most people have multiple mutations in their DNA without ill effects. Mutations are the ultimate source of all new\u00a0genetic variation\u00a0in any\u00a0species.<\/li>\n<li>Mutations may happen spontaneously during <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4549_5559\">DNA replication<\/a> or\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4549_2241\">transcription<\/a>. Other mutations are caused by environmental factors called mutagens. Mutagens include radiation, certain chemicals, and some infectious agents.<\/li>\n<li><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4549_5575\">Germline mutations<\/a> occur in gametes and may be passed onto offspring. Every cell in the offspring will then have the mutation. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4549_5639\">Somatic mutations<\/a> occur in cells other than gametes and are confined to just one cell and its daughter cells. These mutations cannot be passed on to offspring.<\/li>\n<li><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4549_2388\">Chromosomal alterations<\/a> are mutations that change chromosome structure and usually affect the organism in multiple ways.\u00a0Charcot-Marie-Tooth disease type 1\u00a0is an example of a chromosomal alteration in humans.<\/li>\n<li><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4549_2389\">Point mutations<\/a> are changes in a single nucleotide. The effects of point mutations depend on how they change the\u00a0genetic code\u00a0and may range from no effects to very serious effects.<\/li>\n<li><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4549_2392\">Frameshift mutations<\/a> change the reading frame of the\u00a0genetic code\u00a0and are likely to have a drastic effect on the encoded\u00a0protein.<\/li>\n<li>Many mutations are neutral and have no effect on the organism in which they occur. Some mutations are beneficial and improve fitness. An example is a mutation that confers antibiotic\u00a0resistance\u00a0in\u00a0bacteria. Other mutations are harmful and decrease fitness, such as the mutations that cause\u00a0genetic disorders\u00a0or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4549_5605\">cancers<\/a>.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<div class=\"textbox textbox--exercises\">\n<header class=\"textbox__header\">\n<h1 class=\"textbox__title\"><span style=\"color: #ffffff;\">5.8 Review Question<\/span><\/h1>\n<\/header>\n<div class=\"textbox__content\">\n<ol>\n<li>Define mutation.<\/li>\n<li>Identify causes of mutation.<\/li>\n<li>Compare and contrast germline and somatic mutations.<\/li>\n<li>Describe chromosomal alterations, point mutations, and frameshift mutations. Identify the potential effects of each type of mutation.<\/li>\n<li>Why\u00a0do many mutations have neutral effects?<\/li>\n<li>Give one\u00a0example of a beneficial mutation and one\u00a0example of a harmful mutation.<\/li>\n<li>\n<div id=\"h5p-502\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-502\" class=\"h5p-iframe\" data-content-id=\"502\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Mutations\"><\/iframe><\/div>\n<\/div>\n<\/li>\n<li>Why do you think that exposure to mutagens (such as cigarette smoke) can cause cancer?<\/li>\n<li>Explain why the insertion or deletion of a single nucleotide can cause a frameshift mutation.<\/li>\n<li>Compare and contrast missense and nonsense mutations.<\/li>\n<li>Explain why mutations are important to\u00a0evolution.<\/li>\n<\/ol>\n<p>&nbsp;<\/p>\n<\/div>\n<\/div>\n<\/div>\n<div class=\"textbox textbox--examples\">\n<header class=\"textbox__header\">\n<h1 class=\"textbox__title\"><span style=\"color: #ffffff;\">5.8 Explore More<\/span><\/h1>\n<\/header>\n<div class=\"textbox__content\">\n<p><iframe loading=\"lazy\" id=\"oembed-1\" title=\"How Radiation Changes Your DNA\" width=\"500\" height=\"281\" src=\"https:\/\/www.youtube.com\/embed\/PQjL4ZDuq2o?start=51&#38;feature=oembed\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<p style=\"text-align: center;\">How Radiation Changes Your DNA, Seeker, 2016.<\/p>\n<p><iframe loading=\"lazy\" id=\"oembed-2\" title=\"Where do genes come from? - Carl Zimmer\" width=\"500\" height=\"281\" src=\"https:\/\/www.youtube.com\/embed\/z9HIYjRRaDE?start=93&#38;feature=oembed\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<p style=\"text-align: center;\">Where do genes come from? &#8211; Carl Zimmer, TED-Ed, 2014.<\/p>\n<p><iframe loading=\"lazy\" id=\"oembed-3\" title=\"What you should know about vaping and e-cigarettes | Suchitra Krishnan-Sarin\" width=\"500\" height=\"281\" src=\"https:\/\/www.youtube.com\/embed\/a63t8r70QN0?feature=oembed&#38;rel=0&#38;rel=0\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<p style=\"text-align: center;\">What you should know about vaping and e-cigarettes | Suchitra Krishnan-Sarin,<br \/>\nTED, 2019.<\/p>\n<\/div>\n<\/div>\n<h2>Attributions<\/h2>\n<p><strong>Figure 5.8.1<\/strong><\/p>\n<p><a href=\"https:\/\/www.flickr.com\/photos\/patloika\/11027734365\/in\/photostream\/\" rel=\"cc:attributionURL\">Ninja Turtles<\/a>\u00a0by\u00a0<a href=\"https:\/\/www.flickr.com\/photos\/patloika\/\" rel=\"dc:creator\">Pat Loika<\/a> on <a href=\"https:\/\/www.flickr.com\/\">Flickr<\/a> is used under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/\">CC BY 2.0 <\/a>(https:\/\/creativecommons.org\/licenses\/by\/2.0\/<a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\" rel=\"license\">)<\/a> license.<\/p>\n<p><strong>Figure 5.8.2<\/strong><\/p>\n<div>Examples of Mutagens by Christine MIller is used under a <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/\">CC BY SA 4.0<\/a> (https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/) license.<br \/>\nSeparate images are all in public domain or CC licensed:<\/div>\n<ul>\n<li><a style=\"font-size: 1em;\" href=\"https:\/\/pixabay.com\/illustrations\/beauty-treatment-face-mask-girl-163540\/\">Beauty treatment face mask<\/a><span style=\"font-size: 1em;\"> by <\/span><a style=\"font-size: 1em;\" href=\"https:\/\/pixabay.com\/users\/no-longer-here-19203\/\">no-longer-here<\/a><span style=\"font-size: 1em;\"> on <\/span><a style=\"font-size: 1em;\" href=\"https:\/\/pixabay.com\/\">Pixabay<\/a><span style=\"font-size: 1em;\"> is used under the <\/span><a style=\"font-size: 1em;\" href=\"https:\/\/pixabay.com\/service\/license\/\">Pixabay License<\/a><span style=\"font-size: 1em;\"> (https:\/\/pixabay.com\/service\/license\/).<\/span><\/li>\n<li><a href=\"https:\/\/www.flickr.com\/photos\/ajc1\/277161177\">HPV<\/a> by <a class=\"owner-name truncate\" title=\"Go to AJC1's photostream\" href=\"https:\/\/www.flickr.com\/photos\/ajc1\/\" data-track=\"attributionNameClick\">AJC1<\/a> on <a href=\"https:\/\/www.flickr.com\/\">Flickr<\/a> is used under a\u00a0<a href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/2.0\/\">CC BY-NC 2.0<\/a> (https:\/\/creativecommons.org\/licenses\/by-nc\/2.0\/) license.<\/li>\n<li><span style=\"background-color: #ffffff;\"><a style=\"background-color: #ffffff;\" href=\"https:\/\/www.flickr.com\/search\/?user_id=47353092%40N00&amp;view_all=1&amp;text=bacteria\">H Pylori<\/a> by <a class=\"owner-name truncate\" style=\"background-color: #ffffff;\" title=\"Go to AJC1's photostream\" href=\"https:\/\/www.flickr.com\/photos\/ajc1\/\" data-track=\"attributionNameClick\">AJC1<\/a> on <a style=\"background-color: #ffffff;\" href=\"https:\/\/www.flickr.com\/\">Flickr<\/a> is used under a <a style=\"background-color: #ffffff;\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/2.0\/\">CC BY-NC 2.0<\/a> (https:\/\/creativecommons.org\/licenses\/by-nc\/2.0\/) license.\u00a0<\/span><\/li>\n<li><span style=\"font-size: 1em;\"><a href=\"https:\/\/www.flickr.com\/photos\/vaping360\/18539459466\">Vape and Cigarette<\/a> by <a class=\"owner-name truncate\" title=\"Go to Vaping360's photostream\" href=\"https:\/\/www.flickr.com\/photos\/vaping360\/\" data-track=\"attributionNameClick\">Vaping360<\/a><\/span> on <a href=\"https:\/\/www.flickr.com\/\">Flickr<\/a> is used under a <a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\/\">CC BY 2.0<\/a> (https:\/\/creativecommons.org\/licenses\/by\/2.0\/) license.<\/li>\n<li><span style=\"font-size: 1em;\"><a href=\"https:\/\/commons.wikimedia.org\/w\/index.php?curid=12143891\">Hand X-Ray<\/a> by<\/span> <a title=\"User:Hellerhoff\" href=\"https:\/\/commons.wikimedia.org\/wiki\/User:Hellerhoff\">Hellerhoff<\/a> on Wikimedia Commons &#8211; <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/deed.en\">CC BY-SA 3.0 <\/a>(https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/deed.en) license.<\/li>\n<li><a href=\"https:\/\/www.pxfuel.com\/en\/free-photo-obmsy\"><span style=\"font-size: 1em;\">Hot dogs<\/span><\/a><span style=\"font-size: 1em;\"> by unknown on <a href=\"https:\/\/www.pxfuel.com\/\">PxFuel<\/a> is used under the <a href=\"https:\/\/www.pxfuel.com\/terms-of-use\">Pxfuel Terms <\/a>(https:\/\/www.pxfuel.com\/terms-of-use).<\/span><\/li>\n<li>Sunshine face is clipart.<\/li>\n<\/ul>\n<p><strong>Figure 5.8.3<\/strong><\/p>\n<p><span style=\"text-align: initial; font-size: 1em; color: #373d3f;\">Scheme of possible chromosome mutations\/ <a href=\"https:\/\/commons.wikimedia.org\/w\/index.php?curid=1413589\">Chromosomenmutationen<\/a> by unknown on Wikimedia Commons is adapted from N<\/span><span style=\"color: #373d3f; font-size: 1em;\">IH<\/span><span style=\"text-align: initial; font-size: 1em; color: #373d3f;\">&#8216;s <a href=\"https:\/\/www.genome.gov\/genetics-glossary\/Mutation\">Talking Glossary of Genetics<\/a>. [Changes as described by <a href=\"https:\/\/de.wikipedia.org\/wiki\/Benutzer:Dietzel65\">de:user:Dietzel65<\/a>]. Further use and adapation (text translated to English) by\u00a0<\/span><span style=\"text-align: initial; font-size: 1em; color: #373d3f;\">Christine Miller as image is in the <a style=\"text-align: initial; font-size: 1em;\" href=\"https:\/\/creativecommons.org\/publicdomain\/mark\/1.0\/\" rel=\"license\">public domain<\/a> (https:\/\/en.wikipedia.org\/wiki\/Public_domain).<\/span><\/p>\n<p>&nbsp;<\/p>\n<p><span style=\"font-size: 1.424em; font-weight: bold;\">References<\/span><\/p>\n<p class=\"hanging-indent\">Seeker. (2016, April 23). How radiation changes your DNA. YouTube. https:\/\/www.youtube.com\/watch?v=PQjL4ZDuq2o&amp;feature=youtu.be<\/p>\n<p class=\"hanging-indent\">TED. (2019, June 5). What you should know about vaping and e-cigarettes | Suchitra Krishnan-Sarin. YouTube. https:\/\/www.youtube.com\/watch?v=a63t8r70QN0&amp;feature=youtu.be<\/p>\n<p class=\"hanging-indent\">TED-Ed. (2014, September 22). Where do genes come from? &#8211; Carl Zimmer. YouTube. https:\/\/www.youtube.com\/watch?v=z9HIYjRRaDE&amp;feature=youtu.be<\/p>\n<p class=\"hanging-indent\">Wikipedia contributors. (2020, July 6). Breast cancer. In Wikipedia.\u00a0 https:\/\/en.wikipedia.org\/w\/index.php?title=Breast_cancer&amp;oldid=966366739<\/p>\n<p class=\"hanging-indent\">Wikipedia contributors. (2020, July 9). Charcot\u2013Marie\u2013Tooth disease. In <em>Wikipedia<\/em>. https:\/\/en.wikipedia.org\/w\/index.php?title=Charcot%E2%80%93Marie%E2%80%93Tooth_disease&amp;oldid=966912915<\/p>\n<p class=\"hanging-indent\">Wikipedia contributors. (2020, July 7). Cystic fibrosis. In <em>Wikipedia<\/em>.\u00a0 https:\/\/en.wikipedia.org\/w\/index.php?title=Cystic_fibrosis&amp;oldid=966566921<\/p>\n<p class=\"hanging-indent\">Wikipedia contributors. (2020, June 4). Limone sul Garda. In\u00a0<i>Wikipedia. <\/i>https:\/\/en.wikipedia.org\/w\/index.php?title=Limone_sul_Garda&amp;oldid=960771991<\/p>\n<p class=\"hanging-indent\">Wikipedia contributors. (2020, June 23). Ovarian cancer. In <em>Wikipedia<\/em>.\u00a0 https:\/\/en.wikipedia.org\/w\/index.php?title=Ovarian_cancer&amp;oldid=964157192<\/p>\n<p class=\"hanging-indent\">Wikipedia contributors. (2020, May 7). BRCA mutation. In <em>Wikipedia<\/em>. https:\/\/en.wikipedia.org\/w\/index.php?title=BRCA_mutation&amp;oldid=955463902<\/p>\n<p class=\"hanging-indent\">Wikipedia contributors. (2020, July 10). Teenage Mutant Ninja Turtles. In <em>Wikipedia<\/em>. https:\/\/en.wikipedia.org\/w\/index.php?title=Teenage_Mutant_Ninja_Turtles&amp;oldid=967030468<\/p>\n<p>&nbsp;<\/p>\n<div class=\"glossary\"><span class=\"screen-reader-text\" id=\"definition\">definition<\/span><template id=\"term_4549_2381\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_4549_2381\"><div tabindex=\"-1\"><p>A molecule that can undergo polymerization, creating macromolecules.  Large numbers of monomers combine to form polymers in a process called polymerization.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_4549_277\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_4549_277\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_4549_519\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_4549_519\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_4549_5815\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_4549_5815\"><div tabindex=\"-1\"><p>A population of similar organisms able to breed with one another.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_4549_2382\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_4549_2382\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_4549_5575\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_4549_5575\"><div tabindex=\"-1\"><p>Mutation in cells destined to become egg or sperm cells.  These mutations can be passed to offspring.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_4549_5639\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_4549_5639\"><div tabindex=\"-1\"><p>Mutations acquired by a cell that can be passed to future cells arising from the mutated cell in the course of cell division.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_4549_2388\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_4549_2388\"><div tabindex=\"-1\"><p>A force that acts between the protons and neutrons of atoms.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_4549_2389\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_4549_2389\"><div tabindex=\"-1\"><p>A force that acts between the protons and neutrons of atoms.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_4549_5707\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_4549_5707\"><div tabindex=\"-1\"><p>Amino acids are organic compounds that combine to form proteins.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_4549_6019\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_4549_6019\"><div tabindex=\"-1\"><p>A genetic mutation caused by a deletion or insertion in a DNA sequence that shifts the way the sequence is read.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_4549_5555\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_4549_5555\"><div tabindex=\"-1\"><p>The specific location in DNA where a set of codons will code for a certain protein.  The reading frame begins with the start codon (AUG).<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_4549_5813\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_4549_5813\"><div tabindex=\"-1\"><p>A class of biological molecule consisting of linked monomers of amino acids and which are the most versatile macromolecules in living systems and serve crucial functions in essentially all biological processes.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_4549_5605\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_4549_5605\"><div tabindex=\"-1\"><p>A group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_4549_5643\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_4549_5643\"><div tabindex=\"-1\"><p>A cycle of growth and division that cells go through.  It includes interphase (G1, S, and G2) and the mitotic phase.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_4549_5559\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_4549_5559\"><div tabindex=\"-1\"><p>The process by which DNA is copied.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_4549_2241\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_4549_2241\"><div tabindex=\"-1\"><p>Image shows a labelled diagram highlighting the location of the uterus in pregnancy.  The developing fetus, amniotic fluid and placenta are all housed in the uterus, which stretches to many times its regular size to accommodate pregnancy.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_4549_2392\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_4549_2392\"><div tabindex=\"-1\"><p>Created by CK-12 Foundation\/Adapted by Christine Miller<\/p>\n<figure id=\"attachment_4280\" aria-describedby=\"caption-attachment-4280\" style=\"width: 400px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-4280\" src=\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2019\/06\/Cold-by-spencer-backman-1KdD2iBlnRI-unsplash-scaled-2.jpg\" alt=\"13.1.1 Cold\" width=\"400\" height=\"286\"><figcaption id=\"caption-attachment-4280\" class=\"wp-caption-text\"><em>Figure 13.1.1 Feeling under the weather?<\/em><\/figcaption><\/figure>\n<div>\n<h1>\u00a0Case Study: Cough That Won't Quit<\/h1>\n<\/div>\n<p>Three weeks ago, 20-year-old Erica came down with symptoms typical of the common cold. She had a runny nose, fatigue, and a mild cough. Her symptoms\u00a0were\u00a0starting to improve, but recently, her cough has been getting worse. She is coughing up a lot of thick mucus, her throat is sore from frequent coughing, and her chest feels very congested. According to her grandmother, Erica has a \u201cchest cold.\u201d Erica is a smoker and wonders if her habit is making her cough worse. She decides that it's time to see a doctor.<\/p>\n<p>Dr. Choo examines Erica and asks about her symptoms and health history. She checks the level of oxygen in Erica\u2019s blood by attaching a device called a pulse oximeter to Erica\u2019s finger.<\/p>\n<div>\n<figure id=\"attachment_4281\" aria-describedby=\"caption-attachment-4281\" style=\"width: 475px\" class=\"wp-caption aligncenter\"><img class=\"wp-image-4281\" src=\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/Wrist-oximeter-1.jpg\" alt=\"13.1.2 Oximeter\" width=\"475\" height=\"254\"><figcaption id=\"caption-attachment-4281\" class=\"wp-caption-text\"><em>Figure 13.1.2 A pulse oximeter, used to measure blood oxygen levels.<\/em><\/figcaption><\/figure>\n<\/div>\n<p>Dr. Choo concludes that Erica has <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4549_4282\">bronchitis<\/a>, which is an infection that commonly occurs after a person has a cold or flu. <a href=\"https:\/\/www.mayoclinic.org\/diseases-conditions\/bronchitis\/symptoms-causes\/syc-20355566#:~:text=Bronchitis%20is%20an%20inflammation%20of,be%20either%20acute%20or%20chronic.\">Bronchitis<\/a> is sometimes referred to as a \u201cchest cold,\u201d so Erica\u2019s grandmother was right! Bronchitis causes inflammation and a build up of mucus in the bronchial tubes in the chest.<\/p>\n<p>Because bronchitis is usually caused by <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4549_4283\">viruses<\/a> and not <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4549_2588\">bacteria<\/a>, Dr. Choo tells Erica that antibiotics are not likely to help. Instead, she recommends that Erica try to thin out and remove the mucus by drinking plenty of fluids and using a humidifier or spending time in a steamy shower. She recommends that Erica get plenty of rest as well.<\/p>\n<p>Dr. Choo also tells Erica some things <em>not<\/em> to do \u2014 most importantly, to stop smoking while she is sick, and to try to quit smoking in the long-term. She explains that smoking can make people more susceptible to bronchitis and can hinder recovery. Finally, she advises Erica to avoid taking over-the-counter cough suppressant medication.<\/p>\n<p>As you read this chapter about the respiratory system, you will be able to better understand what bronchitis is, and why Dr. Choo made the treatment recommendations that she did. At the end of the chapter, you will learn more about acute bronchitis, which is the type that Erica has. This information may come in handy to you personally, because chances are high that you will get this common infection at some point in your life \u2014 there are millions of cases of bronchitis every year!<\/p>\n<div>\n<div class=\"textbox textbox--learning-objectives\">\n<header class=\"textbox__header\">\n<h1 class=\"textbox__title\"><span style=\"color: #ffffff\">Chapter Overview: Respiratory System<\/span><\/h1>\n<\/header>\n<div class=\"textbox__content\">\n<p>In this chapter, you will learn about the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_4549_2912\">respiratory system<\/a> \u2014 the system that exchanges gases (such as oxygen and carbon dioxide) between the body and the outside air. Specifically, you will learn about:<\/p>\n<ul>\n<li>The process of respiration, in which oxygen moves from the outside air into the body and carbon dioxide and other waste gases move from inside the body into the outside air.<\/li>\n<li>The organs of the respiratory system, including the lungs, bronchial tubes, and the rest of the respiratory tract.<\/li>\n<li>How the respiratory tract protects itself from pathogens and other potentially harmful substances in the air.<\/li>\n<li>How the rate of breathing is regulated to maintain homeostasis of blood gases and pH.<\/li>\n<li>How ventilation, or breathing, allows us to inhale air into the body and exhale air out of the body.<\/li>\n<li>The conscious and unconscious control of breathing.<\/li>\n<li>Nasal breathing compared to mouth breathing.<\/li>\n<li>What happens when a person is drowning.<\/li>\n<li>How gas exchange occurs between the air and blood in the alveoli of the lungs, and between the blood and cells throughout the body.<\/li>\n<li>Disorders of the respiratory system, including asthma, pneumonia, chronic obstructive pulmonary disease (COPD), and lung cancer.<\/li>\n<li>The negative health effects of smoking.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<div class=\"textbox shaded\">\n<p>As you read the chapter, think about the following questions:<\/p>\n<ol>\n<li>Where are the bronchial tubes? What is their function?<\/li>\n<li>What is the function of mucus? Why can too much mucus be a bad thing?<\/li>\n<li>Why did Dr. Choo check Erica\u2019s blood oxygen level?<\/li>\n<li>Why do you think Dr. Choo warned Erica to avoid cough suppressant medications?<\/li>\n<li>How does acute bronchitis compare to chronic bronchitis? How do they both relate to smoking?<\/li>\n<\/ol>\n<\/div>\n<h2>Attributions<\/h2>\n<\/div>\n<p><strong>Figure 13.1.1<\/strong><\/p>\n<p><a href=\"https:\/\/unsplash.com\/photos\/1KdD2iBlnRI\" rel=\"cc:attributionURL\">Cold\/ Look into my eyes forever<\/a> [photo] by <a class=\"_3XzpS _1ByhS _4kjHg _1O9Y0 _3l__V _1CBrG xLon9\" href=\"https:\/\/unsplash.com\/@spencerbackman\">Spencer Backman<\/a> on <a href=\"https:\/\/unsplash.com\/\">Unsplash<\/a> is used under the <a class=\"ICezk _2GAZm _2WvKc\" href=\"https:\/\/unsplash.com\/license\">Unsplash License<\/a> (https:\/\/unsplash.com\/license).<\/p>\n<p><strong>Figure 13.1.2<\/strong><\/p>\n<p><a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Wrist-oximeter.jpg\" rel=\"cc:attributionURL\">Wrist-oximeter<\/a> by <a class=\"new\" title=\"User:UusiAjaja (page does not exist)\" href=\"https:\/\/commons.wikimedia.org\/w\/index.php?title=User:UusiAjaja&amp;action=edit&amp;redlink=1\">UusiAjaja<\/a> on Wikimedia Commons is used under a <a href=\"https:\/\/creativecommons.org\/publicdomain\/zero\/1.0\/deed.en\">CC0 1.0<\/a> Universal Public Domain Dedication (https:\/\/creativecommons.org\/publicdomain\/zero\/1.0\/deed.en) license.<\/p>\n<p><span style=\"font-size: 1.424em;font-weight: bold\"><br \/>\nReference<\/span><\/p>\n<p class=\"hanging-indent\">Mayo Clinic Staff. (n.d.). Bronchitis [online article]. Mayoclinic.org. https:\/\/www.mayoclinic.org\/diseases-conditions\/bronchitis\/symptoms-causes\/syc-20355566<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><\/div>","protected":false},"author":32,"menu_order":8,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":"cc-by-nc"},"chapter-type":[48],"contributor":[],"license":[55],"class_list":["post-4549","chapter","type-chapter","status-publish","hentry","chapter-type-numberless","license-cc-by-nc"],"part":4507,"_links":{"self":[{"href":"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-json\/pressbooks\/v2\/chapters\/4549","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-json\/wp\/v2\/users\/32"}],"version-history":[{"count":4,"href":"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-json\/pressbooks\/v2\/chapters\/4549\/revisions"}],"predecessor-version":[{"id":6399,"href":"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-json\/pressbooks\/v2\/chapters\/4549\/revisions\/6399"}],"part":[{"href":"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-json\/pressbooks\/v2\/parts\/4507"}],"metadata":[{"href":"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-json\/pressbooks\/v2\/chapters\/4549\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-json\/wp\/v2\/media?parent=4549"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-json\/pressbooks\/v2\/chapter-type?post=4549"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-json\/wp\/v2\/contributor?post=4549"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-json\/wp\/v2\/license?post=4549"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}