Exam 1 Flashcards
Define allosterism?
Enzyme activity hanged with non competitive binding of no substrate at allosterism sites other than the active sites of enzymes
State the location of glycolysis?
Cytosol
Describe regulation of glycolysis?
The pathway is regulated by products and intermediates.
PFK is key
What regulates PFK?
ATP and citrate
What regulates hexokinase?
G6P
F6P (not good regulator due to products being used in two pathways)2
What regulates pyruvate kinase?
Acetyl-CoA
ATP
Alanine
Explain why PFK is the key regulatory enzyme of glycolysis?
PFK’s reaction is unique to glycolysis and is a better site to more tightly control the reaction
Explain how blood glucose levels control the activity of pyruvate kinase?
If blood glucose levels are low, pyruvate kinase decreases thus slowing the pathways of glycolysis
Explain the advantages of phosphorylating glucose when it enters the cell?
Traps glucose in the cell
Phosphate groups create high energy bonds
Keeps intracellular concentrations of glucose low
Favors glucose diffusion into the cell
Explain the disadvantages of phosphorylating glucose when it enters the cell?
Cells do not readily give it up
What are the traits of hexokinase?
Catalyzes the first step
Inhibitors of PFK inhibits hexokinase
PFK increases F6P and then G6P
What are the traits of glucokinase?
Alternative form of hexokinase
Glucokinase also makes G6P, but only does this if glucose is abundant
Provides G6P for synthesis of glycogen
Affinity of glucokinase for G6P allows brain and muscle the first shot of utilizing glucose(lesser affinity for glucose)
State the circumstances where lactate is produced?
- lactate is produced to buy time and allow temporary over-running of glycolysis
- made to reform NAD+ for use in pathway to keep glycolysis running
- pyruvate + NADH+ H+ —> (lactate dehydrogenase) —> lactate + NAD+
Explain the relationship between lactate production and NADH?
- lactate is produced to buy time and allow temporary over-running of glycolysis
- made to reform NAD+ for use in pathway to keep glycolysis running
- pyruvate + NADH+ H+ —> (lactate dehydrogenase) —> lactate + NAD+
- NAD+ is generated to continue glycolysis
State the net production of ATP from glycolysis?
Net yield of ATP in glycolysis is 2 ATP
4 total produced in 2nd half of reaction, but 2 were utilized in first half of reaction
Contrast bis and di phosphates?
Bis– 2 separate phosphates on molecule
Di— 2 joined phosphates on molecule
State the synonyms for the citric acid cycle?
Kreb’s cycle
TCA cycle
State the location of the Krebs cycle?
Mitochondrial matrix
What TCA reaction is inhibited by Acetyl CoA?
Pyruvate –> Acetyl CoA
What TCA reaction is inhibited by NADH?
Pyruvate–> Acetyl CoA
Acetyl CoA –> Citrate
Alpha-Ketoglutarate–> Succinyl-CoA
What TCA reaction is inhibited by ATP?
Pyruvate –> Acetyl CoA
Acetyl CoA–> Citrate
Isocitrate —> alpha-Ketoglutarate
What TCA reaction is inhibited by Succinyl CoA?
Acetyl-CoA –> Citrate
Alpha-Ketoglutarate –> Succinyl CoA
What TCA reaction is stimulated by NAD+?
Pyruvate –>Acetyl CoA
Isocitrate –> alpha-Ketoglutarate
What TCA REACTION IS STIMULATED BY CoA?
Pyruvate –> Acetyl CoA
What TCA reaction is stimulated by ADP?
Isocitrate –> alpha-Ketoglutarate
What TCA reaction is stimulated by AMP?
Alpha-Ketoglutarate –> Succinyl CoA
What are the inhibitors and stimulators of Citrate synthase?
Inhibit: ATP, NADH, Succinyl-CoA
Stimulates: none
What are the inhibit and stimulate of isocitrate dehydrogenase?
inhibit: ATP
Stimulates: ADP, NAD+
What are the inhibit and stimulate of alpha-Ketoglutarate?
Inhibit: NADH, Succinyl-CoA
Stimulates: AMP
Define catapleurotic?
Taking something away from the cycle
Define anapleurotic?
Giving something to the cycle
