Chapter 14 - Exam 3 Flashcards
Glycolysis
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
Preparatory Phase
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)
Payoff Phase
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)
Pathways for pyruvate after glycolysis.
- Under aerobic conditions, pyruvate is oxidized to acetyl-CoA
- Under anaerobic conditions, pyruvate is reduced to lactate or ethanol
- NADH must be recycled to regenerate NAD+
Fermentation
processes that extract energy (as ATP) but do not consume oxygen or change the concentrations of NAD+ or NADH
Fermentation: Importance of oxidizing NADH
oxidizing NADH is important because its electrons are used to reduce pyruvate into lactate; lactate can then be recycle (converted to glucose during recovery)
Glucogenesis
pathway that converts pyruvate and related three and four-carbon compounds to glucose (mainly occurs in the liver in mammals)
3 steps that are not the reverse of glycolysis (why?)
Steps 1, 3, and 10
Essentially irreversible because they have a large negative delta G
Pentose Phosphate Pathway
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)
What type of cells use pentose phosphate pathway?
-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