Glycolysis

Question 1

Preparatory Phase

Answer 1

six carbon hexose doubly phosphorylated and split into two phosphorylated 3-carbon units using 2 ATP
(steps 1-4)

Question 2

Payoff Phase

Answer 2

3-carbon intermediates oxidized and rearranged to form pyruvate, gain 4 ATP and 2 NADH
(steps 6-10)

Question 3

Step 1

Answer 3

Phosphorylation of Glucose (prevents glucose from diffusing through cell membrane due to negative charge, phosphate activates glucose so enzyme can bind)
reaction: glucose =(ATP=>ADP)=> glucose 6-phosphate
enzyme: hexokinase
ΔG’°= -16.7 kJ/mol

Question 4

Step 2

Answer 4

Isomerization (acid-base catalyzed- bind and open, base takes a proton, base returns protons, returns to cyclic)
reaction: glucose 6-phosphate =(Mg2+)=> fructose 6-phosphate
enzyme: phosphohexose isomerase
ΔG’°= 1.7 kJ/mol

Question 5

Step 3

Answer 5

Second Phosphorylation
reaction: fructose 6-phosphate =(ATP=>ADP)=> fructose 1,6-phosphate
enzyme: phosphofructokinase-1 (PFK-1)
- regulated by ATP binding to active and allosteric sites
ΔG’°= -14.2 kJ/mol

Question 6

Step 4

Answer 6

Lysis
reaction: fructose 1,6-phosphate => dihydroxyacetone phosphate + glyceraldehyde 3-phosphate
enzyme: aldolase
ΔG’°= 23.8 kJ/mol

Question 7

Step 5

Answer 7

Isomerization

reaction: dihydroxyacetone phosphate => glyceraldehyde 3-phosphate
enzyme: triode phosphate isomerase

Question 8

Step 6

Answer 8

Oxidation
reaction: glyceraldehyde 3-phosphate + Pi =(NAD+=>NADH + H+)=> 1,3-bisphosphoglycerate
enzyme: glyceraldehyde 3-phosphate dehydrogenase
ΔG’°= 6.3 kJ/mol

Question 9

Step 7

Answer 9

Phosphate Transfer (substrate level phosphorylation, reaction is catalyzed in both reactions)
reaction: 1,3-bisphosphoglycerate + ADP => 3-phosphoglycerate + ATP
enzyme: phosphoglycerate kinase
ΔG’°= -18.5 kJ/mol

Question 10

Step 8

Answer 10

Add and Remove a Phosphate
reaction: 3-phosphoglycerate =(Mg2+)=> 2-phosphoglycerate
enzyme: phosphoglycerate mutase
- has a phosphate group on second active site His which
acts as a general base catalyst
- C3 phosphate transferred to first active site His and
second acid site His acts as a general acid catalyst
ΔG’°= 4.4 kJ/mol

Question 11

Step 9

Answer 11

Dehydration
reaction: 2-phosphoglycerate =(H2O released)=> phosphoenolpyruvate
enzyme: enolase
ΔG’°= 7.5 kJ/mol

Question 12

Step 10

Answer 12

Phosphate Transfer
reaction: phosphoenolpyruvate + ADP =(Mg2+, K+)=> pyruvate + ATP
enzyme: pyruvate kinase
ΔG’°= -31.4 kJ/mol

Question 13

Hexokinase

Answer 13

step 1
glucose => glucose 6-phosphate
ΔG’°= -16.7 kJ/mol

Question 14

Phosphohexose Isomerase

Answer 14

step 2
uses Mg2+
glucose 6-phosphate => fructose 6-phosphate
ΔG’°= 1.7 kJ/mol

Question 15

Phosphofructokinase-1 (PFK-1)

Answer 15

step 3
converts ATP => ADP and uses Mg2+
fructose 6-phosphate => fructose 1,6-bisphosphate
ΔG’°= -14.2 kJ/mol

Question 16

Aldolase

Answer 16

step 4
fructose 1,6-bisphosphate => dihydroxyacetone + glyceraldehyde 3-phosphate
ΔG’°= 23.8 kJ/mol

Question 17

Triode Phosphate Isomerase

Answer 17

step 5

dihydroxyacetone => glyceraldehyde 3-phosphate

Question 18

Glyceraldehyde 3-Phosphate Dehydrogenase

Answer 18

step 6
converts NAD+ to NADH + H+
glyceraldehyde 3-phosphate + Pi => 1,3-bisphosphoglycerate
ΔG’°= 6.3 kJ/mol

Question 19

Phosphoglycerate Kinase

Answer 19

step 7
1,3-bisphosphoglycerate + ADP => 3-phosphoglycerate + ATP
ΔG’°= -18.5 kJ/mol

Question 20

Phosphoglycerate Mutase

Answer 20

step 8
uses Mg2+
3-phosphoglycerate => 2-phosphoglycerate
ΔG’°= 4.4 kJ/mol

Question 21

Enolase

Answer 21

step 9
releases H2O
2-phosphoglycerate => phosphoenolpyruvate
ΔG’°= 7.5 kJ/mol

Question 22

Pyruvate Kinase

Answer 22

step 10
uses Mg2+ and K+
phosphoenolpyruvate + ADP => pyruvate + ATP
ΔG’°= -31.4 kJ/mol

Question 23

SCORE BOARD

Answer 23

used: 1 glucose, 2 ATP, 2 Pi, 2 NAD+
made: 4 ATP, 2 H+, 2 pyruvate, 2 NADH
3. 5% of available energy in glucose made