Chapter 14 - Exam 3

Question 1

Glycolysis

Answer 1

process by which a molecule of glucose is degraded in a series of enzyme-catalyzed reactions to yield two molecules of the three-carbon compound pyruvate (some energy is conserved

Question 2

Preparatory Phase

Answer 2

ATP is consumed, delta G of the intermediates increases, hexose carbon chains are converted to glyceraldehyde 3-phosphate (phosphorylation of glucose and conversion to glyceraldehyde 3-phosphate)

Question 3

Payoff Phase

Answer 3

yields (energy conserved as 2 ATP and 2 NADH) and 2 pyruvate (conversion of glyceraldehyde 3-phosphate to pyruvate and release of energy/storage in ATP and NADH)

Question 4

Pathways for pyruvate after glycolysis.

Answer 4

1. Under aerobic conditions, pyruvate is oxidized to acetyl-CoA
2. Under anaerobic conditions, pyruvate is reduced to lactate or ethanol
3. NADH must be recycled to regenerate NAD+

Question 5

Fermentation

Answer 5

processes that extract energy (as ATP) but do not consume oxygen or change the concentrations of NAD+ or NADH

Question 6

Fermentation: Importance of oxidizing NADH

Answer 6

oxidizing NADH is important because its electrons are used to reduce pyruvate into lactate; lactate can then be recycle (converted to glucose during recovery)

Question 7

Glucogenesis

Answer 7

pathway that converts pyruvate and related three and four-carbon compounds to glucose (mainly occurs in the liver in mammals)

Question 8

3 steps that are not the reverse of glycolysis (why?)

Answer 8

Steps 1, 3, and 10
Essentially irreversible because they have a large negative delta G

Question 9

Pentose Phosphate Pathway

Answer 9

pathway that oxidizes glucose 6-phosphate, producing pentose phosphates and NADPH (helps provide precursors for nucleotide and amino acid biosynthesis, reducing molecules for anabolism, and lessen oxidative stress)

Question 10

What type of cells use pentose phosphate pathway?

Answer 10

-Rapidly dividing cells use ribose 5-phosphate to make RNA, DNA, and coenzymes
-Tissues that carry out extensive fatty acid synthesis (liver) require NADPH
-Tissues that actively synthesize cholesterol and steroid hormones (liver, gonads) require NADPH