glycolysis flash

Question 1

Questions

Answer 1

Answers

Question 2

Glycolysis 1st regulated step

Answer 2

Hexokinase (inhibited by G6P)(low Km for glucose)/ Glucokinase (liver and pancreas)(under low BGL, GK in sequestered in nucleus). Trap glucose as G6P in cell

Question 3

Glycolysis 2nd regulated step

Answer 3

Phosphofructokinase-1. Major regulated step, sugar commited to glycolytic pathway. Inhibitors: ATP and citrate. Activators: F2,6 BP (links glycolysis to hormonal regulation) and AMP

Question 4

Glyceraldehyde-3P DH

Answer 4

Enzyme requires sulfhydral group from Cys. Generates NADH

Question 5

Glycolysis 3rd regulated step

Answer 5

Pyruvate kinase. PEP–>Pyruvate + ATP. 3 forms of PK (L: liver, M1/M2: muscle/other, R: RBC)

Question 6

Cardiac PFK-2

Answer 6

Phosphorylated by insulin-stimulated PKB or AMP-activated PK, when phosphorylated its kinase activity is active (opposite of lver PFK2). Allows heart glycolysis to be active under low energy conditions or when glucose is high (insulin release)

Question 7

Liver Pyruvate kinase

Answer 7

Activate: High PEP or F 1,6 BP. Inhibit: high ATP, alanine, covalent modification by cAMP dep. PKA (phosphorylation)

Question 8

PKA

Answer 8

c-AMP dependent Protein Kinase A. Glucagon/ epinephrine activates adenyl cyclase ATP–> c-AMP. Then PKA R2C2 + c-AMP–> R-cAMP + C. Then “C” causes phosphorylation and inactivation of PFK-2 and PK in liver. Liver then exports glucose and makes gluco via gluconeogenesis.

Question 9

Cori Cycle

Answer 9

Muscle forms lactate to regenerate NAD+ to continue glycolysis. Carbons form lactate reach liver and help make glucose which is exported via blood to muscle.

Question 10

Fructokinase

Answer 10

Very active in converting Fructose to F1P. Require ATP. IV fructose load causes rapid P depletion

Question 11

Amylose

Answer 11

Major form of carbohydrate, comes from starch. Repeating glu alpha(1,4) glu

Question 12

Amylopectin

Answer 12

Starch also. Alpha (1,4) and alpha (1,6)

Question 13

Lactose

Answer 13

gal beta (1,4) glu

Question 14

Sucrose

Answer 14

glu alpha (1,2) fru

Question 15

Endoglycosidase

Answer 15

cleaves alpha (1,4). From salivary amylase. Creates dextrins

Question 16

cellulose

Answer 16

glu beta (1,4) glu. No human enzymes to hydrolyze

Question 17

Pyruvate carboxylase

Answer 17

Enzyme to reverse glycolysis. Pyruvate + ATP + CO2 + Biotin –> OAA. Mitochondria. Activated by acetyl-CoA

Question 18

PEP Carboxykinase

Answer 18

Enzyme to reverse glycolysis. OAA + GTP –> CO2 + GDP + PEP. Cyto.

Question 19

Fructose 1,6 Bisphosphatase

Answer 19

Enzyme to reverse glycolysis. F1,6BP –> F6P + P. Cyto. Activate: ATP/ citrate. Inhibit: F2,6 BP/ AMP (reverse of PFK1)

Question 20

G6 Phosphatase

Answer 20

Enzyme to reverse glycolysis. G6P–> Glucose + P. Only in liver and kidney. Cyto.

Question 21

Pyruvate DH

Answer 21

Inhibited by acetyl-CoA