{"id":247,"date":"2019-06-24T12:45:03","date_gmt":"2019-06-24T16:45:03","guid":{"rendered":"https:\/\/pressbooks.bccampus.ca\/053humanbiology\/chapter\/4-11-anaerobic-processes\/"},"modified":"2025-02-12T12:37:00","modified_gmt":"2025-02-12T17:37:00","slug":"4-11-anaerobic-processes","status":"publish","type":"chapter","link":"https:\/\/pressbooks.bccampus.ca\/053humanbiology\/chapter\/4-11-anaerobic-processes\/","title":{"raw":"4.11\u00a0Anaerobic Processes","rendered":"4.11\u00a0Anaerobic Processes"},"content":{"raw":"Created by:\u00a0CK-12\/Adapted by Christine Miller<\/span>\r\n\r\n[caption id=\"attachment_246\" align=\"aligncenter\" width=\"400\"]\"Image Figure 4.11.1 Sprinters racing on a track.\u00a0<\/em>[\/caption]\r\n

Fast and Furious<\/h1>\r\nThese sprinters' muscles\u00a0will need a lot of\u00a0energy\u00a0to complete this short race, because they will be running at top\u00a0speed. The action won't last long, but it will be very intense. The energy each sprinter needs can't be provided quickly enough by aerobic\u00a0cellular respiration. Instead,\u00a0their muscle\u00a0cells must use a\u00a0different process to power their activity.\r\n
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Making ATP Without Oxygen<\/h1>\r\n<\/div>\r\nLiving things'\u00a0cells\u00a0power their activities with the energy-carrying molecule [pb_glossary id=\"1240\"]ATP[\/pb_glossary] (adenosine triphosphate). The\u00a0cells\u00a0of most living things make ATP from [pb_glossary id=\"1191\"]glucose[\/pb_glossary] in the process of [pb_glossary id=\"1328\"]cellular respiration[\/pb_glossary]. This process occurs in three stages:\u00a0[pb_glossary id=\"1969\"]glycolysis[\/pb_glossary], the\u00a0[pb_glossary id=\"2037\"]Krebs cycle[\/pb_glossary], and\u00a0[pb_glossary id=\"1202\"]electron transport[\/pb_glossary]. The latter two stages require oxygen, making cellular respiration an [pb_glossary id=\"1762\"]aerobic[\/pb_glossary] process. When oxygen is not available in cells, the ETS quickly shuts down.\u00a0 Luckily, there are also ways of making ATP from glucose which are\u00a0[pb_glossary id=\"1773\"]anaerobic[\/pb_glossary],<\/strong>\u00a0which means that they do not require oxygen. These processes are referred to collectively as\u00a0[pb_glossary id=\"1274\"]anaerobic respiration[\/pb_glossary]<\/strong>.\r\n
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Fermentation<\/h1>\r\n<\/div>\r\nOne important way of making ATP without oxygen is [pb_glossary id=\"1466\"]fermentation[\/pb_glossary]. <\/strong>Similar to aerobic cellular respiration, fermentation starts with [pb_glossary id=\"1969\"]glycolysis[\/pb_glossary], which converts glucose into pyruvate without requiring oxygen. In aerobic cellular respiration the pyruvate that is formed by glycolysis would go to the [pb_glossary id=\"2037\"]citric acid cycle[\/pb_glossary] and [pb_glossary id=\"1202\"]electron transport chain[\/pb_glossary]. However, in fermentation the pyruvate follows another pathway. There are two types of fermentation: [pb_glossary id=\"1405\"]alcoholic fermentation[\/pb_glossary] and [pb_glossary id=\"1522\"]lactic acid fermentation[\/pb_glossary]. Of these, only lactic acid fermentation takes place inside the human body.\r\n

Alcoholic Fermentation<\/h2>\r\n[caption id=\"attachment_246\" align=\"alignleft\" width=\"443\"]\"\" Figure 4.11.2 In alcoholic fermentation, pyruvate is converted to ethanol and carbon dioxide.\u00a0 During this process, NAD+ is formed, which allows glycolysis to continue making ATP.<\/em>[\/caption]\r\n\r\n[pb_glossary id=\"1405\"]Alcoholic fermentation[\/pb_glossary]\u00a0<\/strong>is carried out by single-celled\u00a0fungi\u00a0(called yeasts), as well as some\u00a0bacteria. We use alcoholic fermentation in these organisms to make [pb_glossary id=\"1809\"]biofuels[\/pb_glossary], bread, and wine. The biofuel ethanol<\/a> (a type of alcohol), for example, is produced by alcoholic fermentation of the glucose in corn or other plants. The process by which this happens is summarized in the diagram above. The two pyruvic acid molecules shown in the diagram come from the splitting of glucose in the first stage of the process (glycolysis). ATP is also made during glycolysis. Two molecules of ATP are produced from each molecule of glucose.\r\n\r\n[caption id=\"attachment_3020\" align=\"alignright\" width=\"300\"]\"Image Figure 4.11.3 Holes in bread created by carbon dioxide.[\/caption]\r\n\r\nYeasts in bread dough also use alcoholic fermentation for\u00a0energy. They produce carbon dioxide\u00a0gas\u00a0as a waste product. The carbon dioxide released causes bubbles in the dough and explains why the dough rises. Do you see the small holes in the bread pictured\u00a0to the right? The holes were formed by bubbles of carbon dioxide\u00a0gas.\r\n
\r\n\r\nAs you have probably guessed, yeast is also used in producing alcoholic beverages.\u00a0 When making beer, brewers will add yeast to a mix of barley and hops.\u00a0 In the absence of oxygen, yeast will carry out alcoholic fermentation in order to convert the glucose in the barley into energy, producing the alcohol content as well as the carbonation present in beer.\r\n\r\nLactic Acid Fermentation<\/span>\r\n\r\n<\/div>\r\n[pb_glossary id=\"1522\"]Lactic acid fermentation[\/pb_glossary]<\/strong>\u00a0is carried out by certain\u00a0bacteria, including the bacteria in yogurt. It is also carried out by your muscle cells when you work them hard and fast. This is how the\u00a0muscles\u00a0of the sprinters pictured\u00a0above\u00a0get\u00a0energy\u00a0for their\u00a0short-lived \u2014\u00a0but intense \u2014 activity. When this happens, your muscles are using ATP faster than your cardiovascular system can deliver oxygen!\u00a0 The process\u00a0by\u00a0which this happens is summarized in the diagram\u00a0below. Again, the two pyruvic acid molecules shown in the diagram come from the splitting of glucose in the first stage of the process (glycolysis). It is also during this stage that two ATP molecules are produced. The rest of the processes produce lactic acid. Note that, unlike in alcoholic fermentation, there is no carbon dioxide waste product in lactic acid fermentation.\r\n\r\n[caption id=\"attachment_246\" align=\"aligncenter\" width=\"500\"]\"Image Figure 4.11.4 Lactic acid fermentation formula.<\/em>[\/caption]\r\n\r\n
\r\n\r\nLactic acid fermentation produces lactic acid and NAD+. The NAD+ cycles back to allow glycolysis to continue so more ATP is made. Each circle represents a carbon atom.\r\n\r\n<\/div>\r\nDid you ever run a race, lift heavy weights, or participate in some other intense activity and notice that your\u00a0muscles\u00a0start to feel a burning sensation? This may occur when your muscle cells use lactic acid fermentation to provide ATP for energy. The buildup of lactic acid in the muscles causes\u00a0a burning feeling.\u00a0This painful sensation is useful if it gets you to stop overworking your muscles and allow them a recovery period, during which cells can eliminate the lactic acid.\r\n
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Pros and Cons of Anaerobic Respiration<\/h1>\r\n<\/div>\r\nWith<\/em> oxygen, organisms can use\u00a0aerobic\u00a0cellular respiration to produce up to 38 molecules of ATP from just one molecule of glucose. Without<\/em> oxygen, organisms must use anaerobic respiration to produce ATP, and this process produces only two molecules of ATP per molecule of glucose. Although anaerobic respiration produces less ATP, it has the advantage of doing so very quickly. For example, it allows your muscles to get the energy they need for short bursts of intense activity. Aerobic cellular respiration, in contrast, produces ATP more slowly.\r\n

Fermentation in Food Production<\/h1>\r\nAnaerobic respiration is also used in the food industry.\u00a0 You read about yeast's role in making bread and beer, but did you know that there are many microbes that are used to create the food we eat, including cheese, sour cream, yogurt, soy sauce, olives, pepperoni, and many more.\u00a0 Watch the video below to learn more about fermentation in the food industry.\r\n\r\nhttps:\/\/www.youtube.com\/watch?v=eksagPy5tmQ&t=3s\r\n

The beneficial bacteria that make delicious food - Erez Garty, TED-Ed, 2016.<\/p>\r\n\r\n

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4.11 Cultural Connection<\/span><\/h1>\r\n<\/header>\r\n
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Fishing has always been part of the culture and nutrition of Indigenous peoples living on the west coast of Canada.\u00a0 Fish provides delicious important nutrients such as protein, Omega-3 fatty acids, calcium, iron, and Vitamins A, B, C and D.\u00a0 Traditionally, no part of the fish was wasted, including head, eyes, internal organs, and eggs.<\/span><\/p>\r\nEulachon, also known as candle fish or oolichan, (pictured below) have been prized for their oil for thousands of years. The pathways of these fish dictated \"grease trails\" and are found from Bristol Bay, Alaska, all the way south to the Klamath River, California.\u00a0 Within BC, the areas of Nass, Knights Inlet, and Bella Coola had large trading centres for this important natural resource.\r\n\r\n[h5p id=\"41\"]\r\n\r\nPhotos by Brodie Guy - www.brodieguy.com<\/a> CC BY-NC-ND 4.0<\/a>\r\n\r\n \r\n\r\nEuchalon were and are eaten fresh, smoked or dried, and as grease.\u00a0 The grease remains a highly valued food to Indigenous coastal communities.\u00a0 The flavour of the grease varies greatly depending not only on where the fish is from and how it is made, but also how long it is left to ferment.\u00a0 To ferment the eulachon, fish are left in a wood-lined locker dug into the soil for 10 days.\u00a0 Fermentation uses the action of fungi and bacteria to break down the fish making oil extraction much faster and easier.\r\n\r\nTo learn more, visit the First Nations Health Authority Traditional Foods Fact Sheet<\/a> and a feature in the Yukon News, \"Eulachon, oolicahn, hooligan: A fish by any other name is just as oily.\"<\/a>\r\n\r\n<\/div>\r\n \r\n\r\n<\/div>\r\n \r\n

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4.11 Summary<\/span><\/h1>\r\n<\/header>\r\n
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