Module 8 Flashcards
The biggest energy reserve in a healthy human is:
triacylglycerols in adipose tissue.
During fermentation, the conversion of 2 moles of glucose to 4 moles of lactic acid is accompanied by a net yield of:
4 moles of ATP.
Why is lactate production low when muscles contract under aerobic conditions?
under aerobic conditions most of the pyruvate generated as a result of glycolysis is oxidized by the citric acid cycle rather than reduced to lactate.
How do the catabolic products of fatty acid oxidation enter the TCA cycle?
acetyl CoA
What happens to the heat that is produced when an organism engages in mechanical work?
It is lost to the environment.
Predict what will happen when thermogenin production goes up in the brown fat cells?
ATP synthesis will decrease, and heat generation will increase.
An electron experiences a loss of potential energy when it:
moves to a more electronegative atom.
Describe what is happening in the reaction: Glucose + 6 O2 → 6 CO2 + 6 H2O + Energy:
C6H12O6 is oxidized and O2 is reduced.
The glycolytic production of ATP involves:
substrate-level phosphorylation.
At which step/ process of cellular respiration is oxygen required?
accepting electrons at the end of the electron transport chain
What is the path taken by electrons inside an active mitochondria?
TCA → NADH → ETC → oxygen
What drives ATP production via oxidative phosphorylation?
energy released from movement of protons down their gradient through ATP synthase
ETC pumps protons into which location?
mitochondrial intermembrane space
Which of these chemicals would immediately stop glycolysis? A chemical that
closely mimics the structure of glucose but is not metabolized
During the conversion of glucose to carbon dioxide and water, which stage results in maximal production of ATP?
oxidative phosphorylation
What does proton motive force refer to?
transmembrane proton concentration gradient
Which of these is true regarding glycolysis?
It is found in the cytosol, does not involve oxygen, and is present in most organisms.
What happens to lactate that is produced from pyruvate?
It will be converted back to pyruvate.
The free energy for the oxidation of glucose to carbon dioxide and water is approximately -700 kilocalories per mole and the free energy for the reduction of NAD+ to NADH is +50 kilocalories per mole. Why are only two molecules of NADH formed during glycolysis when it appears that more than a dozen could be formed?
Most of the free energy available from the oxidation of glucose remains in pyruvate.
Describe how the rate of glycolysis is adjusted to meet the cell’s need for ATP. What are the key regulatory enzymes involved and to what regulators do they respond to?
Hexokinase: glucose 6-phosphate
Pyruvate kinase: ATP
Phosphofructokinase-1: activated by AMP and fructose 2,6-bisphosphate, inhibited by ATP
What are the underlying reason for the difference in ATP yield for electrons donated by FADH2 and NADH?
Complex II is not a pump
Discuss the interrelationships between anabolic and catabolic pathways. Provide specific examples in your answer.
ATP powers anabolic reactions, ATP is produced by catabolic reactions
The four stages of glucose oxidation are listed below. Place them in the correct order.
c. conversion in the cytosol of one 6-carbon glucose molecule to two 3-carbon pyruvate molecules
a. pyruvate oxidation to CO2in the mitochondrion via a 2-carbon acetyl CoA intermediate
b. electron transport to generate a proton motive force
d. ATP synthesis in the mitochondrion (oxidative phosophorylation).
During prolonged exercise, oxygen is scarce in muscle tissue. Under these conditions, muscle cells convert pyruvate to two molecules of lactic acid. Explain why, and what happens to the lactic acid that is generated in this way?
Regenerates NAD+
