Homework Clinic
Science Clinic => Health Science => Topic started by: genevieve1028 on Aug 20, 2018
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Describe/summarize the four major stages of catabolism.
Question 2
What percentage of people in poor countries do not have enough to eat?
a. 12
b. 14
c. 16
d. 18
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Answer to Question 1
Stage 1: complex molecules are broken down into their fundamental building blocks.
glycogenolysis glycogen glucose
proteolysis protein amino acids
lipolysis triglycerides fatty acids and glycerol molecules
Stage 2: glucose, amino acids, fatty acids, and glycerol enter specific pathways in which each is converted into an intermediate product that can enter the citric acid cycle.
Stage 3: intermediate products formed during Stage 2 enter the citric acid cycle and are broken down further to form carbon dioxide, releasing energy in the process. Much of the energy released during Stage 3 of metabolism is transferred to the coenzymes NAD+ and FAD, forming NADH + H+ and FADH2, respectively. In addition, small amounts of ATP are formed via substrate phosphorylation.
Stage 4: begins when NADH + H+ and FADH2 enter the electron transport chain. The energy-yielding pathways of oxidative phosphorylation operate in nearly all cells to produce energy for cellular activities.
Answer to Question 2
c