Glycolysis Flashcards

1
Q

Glycolysis net reaction

A

Glucose + 2 ADP + 2 NAD+ + 2 Pi -> 2 pyruvate + 2 ATP + 2 NADH + 2 H+ + 2 H2O

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

2 stages of glycolysis

A

Hexose stage

Triose stage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Differences in ATP usage between hexose stage and triose stage

A

Hexose stage consumes ATP, but triose stage regenerates more ATP than what was consumed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Step 1 of glycolysis

A

Transfer of phosphoryl group from ATP to glucose
Takes place at primary alcohol (most nucleophilic)
Glucose -> glucose 6-phosphate
Enzymes: hexokinase and glucokinase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Isoforms

A

Different structures of an enzyme that have the same function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Step 2 of glycolysis

A

Isomerization: aldose to ketose (proceeds through open-chain form that is generated within the enzyme active site)
Glucose 6-phosphate -> fructose 6-phosphate
Enzyme: glucose 6-phosphate isomerase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Stereospecificity of step 2

A

Highly stereospecific: C-2 epimer isn’t formed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Step 3 of glycolysis

A

Transfer of a 2nd phosphoryl group from ATP to fructose 6-phosphate
Fructose 6-phosphate -> fructose 1,6-bisphosphate
Enzyme: phosphofructokinase-1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Anomeric form of fructose 6-phosphate that phosphofructokinase-1 prefers

A

Beta form

Alpha anomer from step 3 must undergo conformational change

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

First committed step of glycolysis

A

Step 3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Step 4 of glycolysis

A

C3-C4 bond cleavage, yielding 2 triose phosphates
Fructose 1,6-bisphosphate -> dihydroxyacetone phosphate and glyceraldehyde 3-phosphate
Eznyme: aldolase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Portions of fructose 1,6-bisphosphate that DHAP and G3P are derived from

A

DHAP is derived from C1 to C3 of fructose

G3P is derived from C4 to C6 of fructose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Step 5 of glycolysis

A

Rapid interconversion of triose phosphates
DHAP -> G3P
Enzyme: triose phosphate isomerase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Step 6 of glycolysis

A

Oxidation and phosphorylation, yielding a high-energy mixed-acid anhydride
G3P -> 1,3-bisphosphoglycerate
Enzyme: glyceraldehyde 3-phosphate dehydrogenase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Redox reaction in step 6

A

Generation of H+ (NAD+ -> NADH + H+)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Step 7 of glycolysis

A

Transfer of a high-energy phosphoryl group to ADP, yielding ATP
1,3-bisphosphoglycerate -> 3-phosphoglycerate
Enzyme: phosphoglycerate kinase

17
Q

First ATP-generating step of glycolysis

A

Step 7

18
Q

Substrate level phosphorylation

A

Molecule directly transfers phosphoryl group to ADP

19
Q

Step 8 of glycolysis

A

Intramolecular phosphoryl group transfer
3-phosphoglycerate -> 2-phosphoglycerate
Enzyme: phosphoglycerate mutase

20
Q

Mutases

A

Class of isomerase that catalyze transfer of a phosphoryl group from 1 part of a molecule to another

21
Q

Mutase mechanism

A

Enzyme phosphoryl intermediate: phosphoryl group is transferred to enzyme and then transferred back to substrate

22
Q

Step 9 of glycolysis

A

Dehydration to an energy-rich enol ester
2-phosphoglycerate -> phosphoenolpyruvate
Enzyme: enolase

23
Q

Step 10 of glycolysis

A

Transfer of a high-energy phosphoryl group to ADP, yielding ATP
Phosphoenolpyruvate -> pyruvate
Enzyme: pyruvate kinase

24
Q

Metabolically irreversible steps of glycolysis

A
Step 1 (glucose -> glucose 6-phosphate)
Step 3 (fructose 6-phosphate -> fructose 1,6-bisphosphate)
Step 7 (1,3-bisphosphoglycerate -> 3-phosphoglycerate)
Step 10 (phosphoenolpyruvate -> pyruvate)
25
Q

Metabolism of pyruvate to ethanol: what it achieves

A

Survival mechanism of some organisms in long-term anaerobic conditions
Regenerates NAD+ needed for modest energy production

26
Q

2 reactions of pyruvate to ethanol

A
  1. Decarboxylation of pyruvate to acetaldehyde (pyruvate decarboxylase)
  2. Reduction of acetaldehyde to ethanol (alcohol dehydrogenase)
27
Q

Reduction of pyruvate to lactate

A

Lactate dehydrogenase (NADH cofactor) reduces pyruvate to L-lactate
Short-term anaerobic conditions: regeneration of NAD+ in the absence of oxygen
Lactic acid is eventually moved from the muscles to the liver to be converted back to pyruvate

28
Q

Free energy equation

A

delta G= delta G0 + RTln(Q)

Q= current reaction quotient

29
Q

Glycolysis using fructose

A

Fructose is converted into 2 G3P: 2 ATP are invested

30
Q

Glycolysis using galactose

A

Galactose is converted into glucose 1-phosphate through UDP-glucose (galactose is traded for glucose)

31
Q

Glycolysis using mannose

A

Mannose is converted into fructose 6-phosphate (aldose -> ketose)