Energy Qs.Student

Ch. 8-10 Discussion Qs GSIP Intro Bio Name ______________________ Many people today are hooked on “fat free” or low-fat foods. They believe that if something is fat free, we can eat more of it and still maintain our current weight—or even lose weight. We may even think this means we can lose weight without exercising. Often, they are baffled to find that after ignoring the serving size shown on the packaging of these foods, they find themselves gaining weight. If “fat is stored as fat” and they are not eating any fat, why are they getting fatter? When ATP is abundant, cellular respiration slows down and that intermediates of glycolysis and the Krebs cycle can be enzymatically converted to fatty acids and glycerol and packaged into adipose tissue (even if the original energy source was glucose) People are familiar with the muscle “burn” associated with intense exercise. Many of us even know that the burn is caused by lactic acid buildup, but do not know what lactic acid is, or why it causes the burn. Within your workshop group, try to come up with a reason why it causes a burning sensation. Lactic acid is an irritant Dinitrophenol (DNP) is a compound that has the ability to separate the flow of electrons and the pumping of H+ ions for ATP synthesis. This means that the energy from electron transfer cannot be used for ATP synthesis. About 50 years ago, DNP was given as a drug to help patients lose weight. Why does this work? Why would this be dangerous, especially in high doses? Starving the cells. Trematol is a poison derived from the roots of the white snake plant. Cows eating this plant concentrate the poison in their milk. The poison inhibits liver enzymes that convert lactic acid to other compounds for metabolism. Why does physical exertion increase symptoms of poisoning by trematol? Why does the pH of the blood decrease in a person who has digested trematol? Physical exertion would increase the production of lactic acid by fermentation, and the build of lactic acid decreases blood Ph when liver enzymes are blocked. During exertion, our muscles produce lactic acid from pyruvate … Explain why in anaerobic cells the ratio of pyruvate/ lactate is much less than 1 while under aerobic conditions the ratio of pyruvate/ lactate is much greater than 1. Lactate is produced from p In the first step of glycolysis, the enzyme hexokinase uses ATP to transfer a phosphate to glucose to form glucose-6-phosphate. The product continues to be oxidized forming pyruvate in glycolysis and is a precursor to acetyl-CoA for the citric acid cycle (Kreb’s cycle). Suppose that a cell has only glucose available for energy and that the activity of hexokinase is suddenly stopped in this cell. Which of the following conditions will occur and why? The cell will continue to produce energy from mitochondrial electron transport. The cell will continue to produce ATP using the citric acid cycle. The cell will ultimately be unable to produce ATP. The cell will be forced to switch to fermentation to produce ATP. The use of oxygen by the cell will increase. Can’t make ATP During a heart attack, blood flowing to the heart muscle is interrupted by blockage of a coronary artery. Which of the following metabolic activities would you expect to change in the heart? Explain why? (there may be more than one) oxidative phosphorylation would slow down in the mitochondria the rate of production of lactic acid would be stimulated the use of glucose by the muscle tissue would increase the production of water by mitochondria would be inhibited Hummingbirds and nectar-feeding insects eat a diet that is rich in sugars and extremely low in protein. How are these individuals able to synthesize the amino acids and proteins required for growth? They’ll use what’s available. They will convert other things to get what they need. Cyanide (C=N-) blocks complex IV of the electron transport chain. Suggest a hypothesis for what happens to the electron transport chain when complex IV stops working. Your hypothesis should explain why cyanide poisoning is lethal. Flow of e- stops. No ATP=death. When yeast cells are placed in a low-oxygen environment, the mitochondria in these cells become reduced in size and number. Suggest a plausible explanation for this observation. Most agricultural societies have come up with ways to ferment the sugars in barley, wheat, rice corn, or grapes and produce alcoholic beverages. Historians argue that this was an effective way for farmers to preserve the chemical energy in grains and fruits in a form that would not be eaten by rats or spoiled by bacteria or fungi. Why does a great deal of energy remain in the products of fermentation pathways? Compare and contrast substrate level phosphorylation and oxidative phosphorylation. What is the relationship between cellular respiration and fermentation? Why does cellular respiration produce so much more ATP than fermentation?