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Anaerobic Cellular Respiration

Anaerobic Cellular Respiration. 7.4 - Pg. 221-228. Anaerobic Cellular Respiration – No O 2. All Creatures begin the harvesting of energy from glucose with the process of gylcolysis . Gylcolysis requires a continuous supply of NAD + for life.

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Anaerobic Cellular Respiration

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  1. Anaerobic Cellular Respiration 7.4 - Pg. 221-228

  2. Anaerobic Cellular Respiration – No O2 • All Creatures begin the harvesting of energy from glucose with the process of gylcolysis. • Gylcolysis requires a continuous supply of NAD+ for life. • Aerobic respiration creates NAD+ as NADH releases electrons to the ETC—O2 is needed! • Anaerobic production of ATP uses either alcohol fermentation or lactic acid fermentation to cycle NADH into NAD+. • H+ atoms from NADH are transferred to certain organic molecules instead of to the ETC. • 1. Glycolysis – same 10step process used in aerobic respiration. • 2. Fermentation –recycles some of the products of glycolysis in 2 different pathways where either CO2 and ethanol (alcohol fermentation) or lactic acid (lactic acid fermentation) are the final waste products.

  3. Alcohol Fermentation • Occurs in yeast in which NADH passes its H+ atoms to acetaldehyde, generating CO2, ethanol, and NAD+ • The two pyruvates made in glycolysis will later react with NADH to produce ethanol • The final products of 2ethanol molecules is 2NAD+ & 2CO2. • Ethanol (used in alcoholic beverages) the 2 ATP are for the organism’s energy needs. • The net formula:

  4. Applications of Alcohol Fermentation • Humans have used fermentations for years. • Table 1, page 222. Shows some uses

  5. Bread is leavened by mixing live yeast cells with starches (in flour) and water. Yeast ferments the glucose and releases CO2 which makes small bubbles in the bread, the ethanol evaporates away when the bread is baked. • In grape juice the yeast ferments the sugars in the juice, it bubbles as yeast releases CO2(g) and ethanol during fermentation. When there is a 12% concentration of ethanol the yeast cells die and the alcohol beverage is made. • Louis Pasteur provided experimental evidence that yeast was responsible for alcohol fermentation. This helped lead him to the major discovery that many diseases are caused by microbes.

  6. Lactic Acid Fermentation • When aerobic respiration is not sufficient and the O2 is used up because of the high muscle demand for ATP (during strenuous exercise), anaerobic respiration begins. • In strenuous times,lactic acid is madeso that NADH canbe oxidized intoNAD+ so glycolysis can continue.

  7. The overall equation for lactic acid fermentation: • A build up of lactic acid produces stiffness, soreness and fatigue. • Lactic acid is transported through the bloodstream from the muscles to the liver. • When O2 levels return (vigorous exercise ceases), lactic acid is converted back to pyruvate, which then can go through aerobic respiration. • This occurs in the liver. • The extra O2 needed to process lactic acid is called an oxygen debt… ie. Panting for breath.

  8. Exercise Physiology – body’s biological response to exercise: • Control fatigue, dehydration, O2 in bloodstream, shortage of energy… how? • Aerobic fitness is a measure of the ability of the hear, lungs, and bloodstream to supply oxygen to the cells of the body (esp. muscle cells) during physical activity. Moderate exercise with O2 • Maximum oxygen consumption (VO2 max) is the maximum volume of oxygen that the cells of the body can remove from the blood stream in one minute during maximum exertion. • An athlete VO2 max is greater then the average person. • Average person: 35.4mL/kg of body mass/min (poor) • Athlete: 70 mL/kg/min (superior) [biking, marathon, cross-country skiing] • <35.4 very poor, poor: 35.4-38.9, fair -42.4, good -46.8, -52.5 excellent, >52.5 superior

  9. Since O2 can not always reach all mitochondria, lactic acid is always produced. • The body continually is converting lactic acid, but as we exercise the level of lactic acid increases. • The lactic acid threshold is the level of lactic acid in the blood increases sharply. • Exercise below this level canlast for hours, but once youpass that point preventscontinuous exercise.

  10. Supplements and Toxins • Environmental factors can also affect cellular respiration. • Creatinephosphate (occurs naturally in the body and in foods) is used by some athletes as a supplement to supply extra phosphates for cellular respiration ATP production. • Toxins like carbon monoxide (CO) limit the amount of oxygen that is available. • CO binds to hemoglobin, thus preventing O2 from being transported by the blood.

  11. Other toxins, like cyanide and hydrogen sulfide, directly affect specific reactions within cellular respiration process. Thus, preventing the process from actually occurring. • Specifically, cyanide blocks O2 from being the final electron acceptor in the ETC. So no ATP synthesis. • Chemical toxins, such as carbon monoxide, cyanide, and hydrogen sulfide, can hinder cellular respiration.

  12. Homework… • Textbook: • Pg. 222 #1-3 • Pg. 226 #4-6 • Pg. 228 #1-6 • Watch videos and write 5-7 points on each, (hand in paper copy) • Cinnamon buns tomorrow!! 

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