Lesson 11: Glycolysis

Question 1

glycolysis

Answer 1

literally means “the breaking of glucose”
- net exergonic process in cells and under standard conditions

Question 2

glucogenesis

Answer 2

is the “biochemical reversal” of glycolysis

Question 3

cellular localization of glycolsis

Answer 3

• glycolysis occurs in the cytoplasm on eukaryotes and prokaryotes
• is anaerobic, independent of O2

Question 4

STAGE 1

Answer 4

2 ATP investment
reactions 1-4
0 reduced coenzymes
net negative delta G

Question 5

Reaction 1:

Answer 5

Name of RXN: Hexokinase

RXN:
Glucose + ATP –>. Glucose -6- phosphate + ADP

Enzyme Name: Hexokinase (or gluckokinase)

—- Phosphoryl group is added to C-6—–

• transferase, far from equi, no reversible under cellular conditions, ATP consumed (kinase)

Question 6

Reaction 2:

Answer 6

Name of RXN: Phosphoglucoseisomerase

RXN: Glucose-6-Phosphate –> Fructose-6-phosphate

Enzyme Name: Phosphoglucoiosomerase

—– 6 membered ring is converted to a 5 membered ring—-

• Isomerase, Near equi, reversible under cellular conditions depending on [G6P] and [F6P]

Question 7

Reaction 3:

Answer 7

Name of RXN: Phosphofructokinase

RXN:
Fructose -6-P —> Fructose - 1,6 BP

—- (OH to PO4)—-

Enzyme Name: Phosphofructokinase - 1

• transferase, far from equil, not reversible under cellular conditions, kinase, 2nd and last energy inverstiture of glycolysis

!!!!! when a cell wants to turn off glycolysis, it turns it of here!!!!!

Question 8

Reaction 4:

Answer 8

Name of RXN: Aldolase

RXN:
Fructose-1,6 Biphosphate –>
Glyceraldehyde -3-P and Dihydroxyacetone - P

Enzyme Name: Aldolase

—–ring opened up —–

• near equil undner cellular conditions, hydrolase, [DHAP] and [GAP] quickly pulled away so Q is less than 1

Question 9

STAGE 2

Answer 9

• total of 4ATP synthesized in stage II via substrate level phosphorylations
• total of 2 NADH + H+ synthesized
• end product is 2 molecules of pyruvate

Question 10

Reaction 5:

Answer 10

Name of RXN: Triose phosphate isomerase

RXN:
Dihydroxyacetone - Phosphate –> Glyceraldehyde-3-Phosphate

Enzyme Name: Triose phosphate isomerase

• ketose to aldose isomerization, near equil, rxn easily reversible under cellular conditions
  !!!!!! at the end of this step, 2 GAP molecules move throguh the rest of glycolysis

Question 11

Reaction 6:

Answer 11

Name of RXN: Glyceraldehyde 3 phosphate dehydrigenase (GAPDH)

RXN:
Glyceradldehyde-3-phosphate + Pi + NAD+ —> 1,3 Bisphosphoglycerate (1,3 BPG) + NADH + H+

Enzyme:
Glyceraldehyde 3 phosphate

• No ATP consumed Pi is utilized, another phosphoryl trasnfer reaction – NAD+ is a cofactor and first time NADH + H+ produeced, Near rxn

!!!!! lot of potential energy in 1,3 BPG

Question 12

Reaction 7:

Answer 12

Name of RXN: Phosphoglycerate Kinase

RXN:
1,3 Bisphophoglycerate + ADP –> 3 - Phosphoglycerate + ATP

Enzyme Name:
Phosphoglycerate Kinase

Question 13

Reaction 8:

Answer 13

Name of RXN: Phophoglycerate Mutase

RXN:
3-Phosphoglycerate –> 2- Phosphoglycerate

Enzyme Name: Phosphoglycerate mutase

Near EQ rxn, mustases function like isomerases except the phosphte that ends up on C-2 is not the same one that came from C-3

Question 14

Reaction 9:

Answer 14

Name of RXN: Enolase

RXN:
2-phosphoglycerate –> phosphoenolpyruvate + H2O

Enzyme Name: Enolase

• near eq rxn, belongs to a class of enzymes called lyases ( to make or break double bonds through removal of water)

Question 15

Reaction 10:

Answer 15

Name of RXN: Pyrivate Kinase

RXN: phosphoenolpyruvate + ADP –> pyruvate + ATP

Enzyme Name: pyruvate kinase

• far from eq rxn, transferase, kinase, free energy pf RP hydrolysis is conserved in the synthesis of ATP in our second and last SUBSTRATE LEVEL PHOSPHORYLATION

Question 16

which reactions are far from eq:

Answer 16

1,3,10

Question 17

glycolysis summary

Answer 17

• 10 rxns total
• only 1,3 and 10 are far from eq.
• 2 ATP as inputs
• 4 total ATP as output ) for a net of +2 ATP)
• 2 NAD+ as input
• 2NADH + H+ as outputs (these move onto ETC under aerobic conditions)
• 1 glucose yields 2 pyrivate
• catabolic pathway

Question 18

Homolactic Fermentation

Answer 18

NADH+ +H recycled to form NAD+ (lactae dehydrogenase)
ex: muscle cells

Question 19

Alcoholic Fermentation

Answer 19

Pyrivate (w/ pyruvate decarboxylase) –> acetaldehyde –> ethanol