glycolysis

Question 1

glycolysis

Answer 1

breakdown of glucose

Question 2

1st step of glycolysis (prepatory phase)

Answer 2

substrate: glucose
enzyme: hexokinase
product: glucose-6-phosphate
irreversible reaction
energy put into rxn

Question 3

2nd step of glycolysis (prepatory phase)

Answer 3

substrate: glucose-6-phosphate
enzyme: phosphohexose isomerase
product: fructose-6-phosphate
reversible rxn

Question 4

3rd step of glycolysis (prepatory phase)

Answer 4

substrate: fructose-6-phosphate
enzyme: phosphofructokinase-1 (PFK-1)
product: fructose-1,6-bisphosphate
important regulatory step
first committed step of glycolysis & second energy investment
irreversible
energy put into rxn

Question 5

PFK-1 has complex allosteric regulation…

Answer 5

levels high when ATP is depleted & inhibited with high ATP

Question 6

difference between diphosphate and bisphosphate

Answer 6

diphosphate: 2 phosphates connected together
bisphosphate: 2 phosphates not connected

Question 7

4th step of glycolysis (prepatory phase)

Answer 7

substrate: fructose-1,6-bisphosphate
enzyme: aldolase
product: glyceraldehyde 3-phosphate & dihydroxyacetone phosphate
reversible

Question 8

5th step of glycolysis (last step of prepatory)

Answer 8

substrate: dihydroxyacetone
enzyme: triose phosphate isomerase
product: glyceraldehyde 3-phosphate
reversible

Question 9

step 6 of glycolysis (1st step of payoff phase)

Answer 9

substrate: glyceraldehyde 3-phosphate
enzyme: glyceraldehyde 3-phosphate dehydrogenase
product: 1,3-bisphosphoglycerate
reversible
energy released as NADH

Question 10

step 7 of glycolysis (payoff phase)

Answer 10

substrate: 1,3-bisphosphoglycerate
enzyme: phosphoglycerate kinase
product: 3-phosphoglycerate
reversible
1st step where ATP is released

Question 11

step 8 of glycolysis (payoff phase)

Answer 11

substrate: 3-phosphoglycerate
enzyme: phosphoglycerate mutase
product: 2-phosphoglycerate
reversible

Question 12

step 9 of glycolysis (payoff phase)

Answer 12

substrate: 2-phosphoglycerate
enzyme: enolase
product: phosphoenolpyruvate
reversible
removes water

Question 13

step 10 of glycolysis (payoff phase)

Answer 13

substrate:phosphoenolpyruvate
enzyme: pyruvate kinase
product: pyruvate
PK needs K+ or either Mg2+ or Mn2+
pyruvate is initially in enol form
PK allosterically regulated
another regulatory step
non reversible
highly exergonic
releases ATP

Question 14

what happens to pyruvate?

Answer 14

glycolysis forms 2 molecules of pyruvate
aerobic conditions: TCA cycle (Krebs cycle)
anaerobic conditons: 1) 2 lactate molecules formed 2) alcoholic fermentation

Question 15

homolactic fermentation

Answer 15

enzyme: lactate dehydrogenase
reoxidizes NADH to NAD+ for glycolysis
important for muscles during heavy exercise, red blood cells

Question 16

alcoholic fermentation

Answer 16

pyruvate decarboxylase reaction is irreversible
alcohol dehydrogenase reaction is reversible in animals
pyruvate-> acetaldehyde-> ethanol

Question 17

pentose phosphate pathway of glucose oxidation

Answer 17

exists in all cells
from glucose-6-phosphate, you get (1) NADPH
- acts as an electron donor
- needed as an energy source for many biosynthetic rxns
(2) ribose-5-phosphate
- a pentose sugar used in nucleotide and co-enzyme biosynthesis
glucose-6-phosphate->6-phosphogluconate-> ribulose-5-phosphate-> ribose-5-phosphate-> nucleotides, coenzymes, DNA, RNA