Glycolysis

Question 1

Respiration equation

Answer 1

Glucose + 6O2 –> 6CO2 + 6H2O

Question 2

What is glycolysis?

Answer 2

Breaking down of Glucose

Question 3

What happens in the prep phase of glycolysis

Answer 3

Phosphorylation of glucose and its conversion to glyceraldehyde 3-phosphate

Question 4

What are the 3 main overall steps within the prep phase

Answer 4

1) first priming reaction
2) second priming reaction
3) Cleavage of 6 carbon sugar phosphate to 2 3-carbon sugar phosphates

Question 5

Reaction 1 of the prep phase

1) is what
2) catalysed by what in tissues and in liver
3) reversible or irreversible
4) Uses what extras?

Answer 5

1) Phosphorylation of glucose.
Glucose --> glucose6phosphate.
2) Catalysed by hexokinase in tissues
Glucokinase in liver 
3) Irreversible 
4) ATP and Mg2+

Question 6

Reaction 2 of the prep phase

1) is what
2) catalysed by what
3) reversible or nah?
4) What extras?

Answer 6

1) Isomerisation of Glucose 6 phosphate TO Fructose 6 phosphate
2) Catalysed by Phosphohexose Isomerase
3) Reversible
4) Mg2+

Question 7

Reaction 3 of prep phase

1) is what
2) catalysed by what
3) reversible or nah?
4) what extras?
5) first what type of step?

Answer 7

1) Fructose 6 Phosphate TO Fructose 1,6 biphosphate
2) Catalysed by Phosphofructokinase 1 (PFK1)
3) Irreversible
4) ATP, Mg2+
5) First rate limiting step

Question 8

Reaction 4 of prep phase

1) is what
2) catalysed by what
3) reversible or nah?
4) Feature of the enzyme

Answer 8

1) Cleavage of Fructose 1,6 Biphosphate.
Fructose 1,6 Biphosphate TO Dihydroxyacetone Phosphate + Glyceraldehyde 3 Phosphate
2) Aldolase
3) Reversible
4) Enzyme can catalyze the reverse reaction, which is more favourable

Question 9

Reaction 5 of prep phase

1) is what
2) catalysed by what
3) Reversible or nah?
4) How does the enzyme work?
5) What amino acid performs the transfer in the enzyme

Answer 9

1) Isomerisation of DHAP to Glyceraldehyde 3 Phosphate
2) Triose phosphate isomerase
3) Reversible
4) Isomerase pulls a hydrogen atom off one carbon atom and replaces it on a neighbouring carbon atom.
5) A special glutamate amino acid in the active site (Glu165) performs the transfer

Question 10

How many ATP are produced during the Prep phase?

Answer 10

Net loss of 2 ATP in the prep phase

Question 11

What happens after the prep phase of glycolysis?

Answer 11

The payoff phase

Question 12

What happens in the payoff phase?

Answer 12

Oxidative conversion of GA3P to pyruvate and the coupled formation of ATP and NADH

Question 13

What are the 3 main steps in the payoff phase?

Answer 13

1) Oxidation and phosphorylation
2) First ATP forming reaction (Substrate level phosphorylation)
3) Second ATP forming reaction (Substrate level phosphorylation)

Question 14

Reaction 6, first reaction of the payoff phase

1) is what?
2) catalyzed by what?
3) what extras are used?
4) what are the conditions?

Answer 14

1) Oxidation of GA3P TO 1,3Biphosphoglycerate
2) Glyceraldehyde 3 phosphate dehydrogenase
3) NAD+ is turned into NADH + H+
4) Activity of the enzyme depends on the turnover of NAD+ in the cytosol of the cell. Rapid turnover of NAD+ is only achieved under anaerobic conditions

Question 15

Reaction 7, second reaction of the payoff phase

1) is what?
2) Catalysed by what?
3) What extras are used?
4) what is generated at the end finally

Answer 15

1) 1,3BPG to 3-Phosphoglycerate
2) Phosphoglycerate kinase
3) ADP and MG2+(Mg only for the reverse)
4) ATP. Transfers the phosphate from 13BPG to ADP to form ATP

Question 16

Reaction 8, third reaction of the payoff phase?

a) is what?
b) catalysed by what?
c) what extras are used?
d) What is this step priming for?

Answer 16

a) 3-phosphoglycerate to 2-phosphoglycerate
b) Catalysed by phosphoglycerate mutase
c) Mg2+
d) Priming it for phosphate transfer to ADP for a later step

Question 17

Reaction 9, fourth reaction of the payoff phase

1) is what?
2) Catalysed by what?
3) what is released
4) The enzyme is dependent on what?

Answer 17

1) 2 phosphoglycerate to Phosphoenolpyruvate
2) enolase
3) H2O so its a dehydration reaction
4) Mg2+

Question 18

Reaction 10, fifth and final reaction of the payoff phase

1) is what?
2) catalysed by?
3) is the only what reaction of the payoff phase?
4) what does it produce?

Answer 18

1) Conversion of PEP to Pyruvate
2) Catalysed by Pyruvate kinase
3) irreversible. 3rd and final irreversible step of glycolysis
4) ATP

Question 19

What is the overall stoichiometry of glycolysis?

Answer 19

Glucose + 2ATP + 2NAD+ + 4ADP + 2Pi ——> 2 pyruvate + 2 ADP + 2NADH + 2 H+ + 4ATP + 2 H20

Question 20

Glycolysis proceeds up to 10x faster in cancer cells, so some chemotherapy agents inhibit what?

Answer 20

Hexokinase

Question 21

The high glycolytic turnover in cancer cells is also used for what and how?

Answer 21

For diagnosis by injecting isotopically labelled glucose

Question 22

What is the warburg hypothesis?

Answer 22

Most cancel cells produce energy by anaerobic glycolysis rather than oxidation of pyruvate in mitochondria which is common to healthy cells

Question 23

Gluconeogenisis GNG is not simply what?

Answer 23

Is not simply the reverse of glycolysis

Question 24

What is the main difference between GNG and glycolysis

Answer 24

The 3 irreversible steps of glycloysis are catalysed by different enzymes in GNG

Question 25

Describe overall what the differences are between GNG and Glycolysis. Mention the different enzymes if possible briefly

Answer 25

1) Going from pyruvate to PEP is a two step reaction.
Pyruvate to Oxaloacetate. Then Oxaloacetate to PEP.
2) F-1,6-BP to F6P uses fructose 1,6 biphosphatase 1
3) G6P to Glucose uses Glucose 6 phosphatase

Question 26

So converting Pyruvate to PEP is a two step process. the first step

1) is what
2) what enzyme?
3) enzyme located where?
4) what does this enzyme need and add to pyruvate?
5) what does it use as a cofactor?
6) what is used and released meanwhile

Answer 26

1) Pyruvate to Oxaloacetate
2) Pyruvate carboxylase
3) mitochondria
4) This enzyme needs bicarbonate as it adds a carboxylic acid to the pyruvate. COO-
5) Biotin (Vitamin B7) as a cofactor
6) ATP to ADP

Question 27

So converting Pyruvate to PEP is a two step process. the second step

1) is what?
2) What enzyme and where is this enzyme located?
3) uses what and releases what?
4) what else does it release

Answer 27

1) Oxaloacetate to Phosphoenolpyruvate
2) PEP Carboxykinase, cytosol
3) GTP to GDP
4) CO2

Question 28

Converting Fructose 16 BP to Fructose 6 P in GNG

a) what enzyme
b) occurs where?

Answer 28

a) Fructose 1,6-Biphosphatase

b) cytosol

Question 29

Glucose 6 phosphatae to Glucose in GNG

a) what enzyme
b) occurs where in liver
c) occurs where in kidney?

Answer 29

a) Glucose 6 phosphatase
b) lumen of ER in hepatocytes
c) Cortex of the kidney

Question 30

Overall summary of GNG

Answer 30

2 pyruvate + 2H+ + 4H2O + 2NADH + 2GTP + 4ATP —> Glucose + 4ADP + 2GDP+ 6Pi + 2NAD+