Anaerobic Metabolism

Question 1

Definition of glycolysis

Answer 1

Breakdown of glucose into pyruvate which can be converted into acetyl CoA for the TCA cycle

Question 2

Glycolysis pathway

Answer 2

Most important metabolic pathway
Present in all tissues and cell organisms
Function, ATP synthesis, use glucose as fuel

Question 3

Forms of glucose

Answer 3

D glucose (linear)
a-D-glucopyranose (6 membered ring)

Glucose can be in a 5 ring, 6 ring, linear form in solution

Question 4

Sources of glucose for glycolysis

Answer 4

Sugars and starch from diet
Breakdown of stored glycogen from liver
Recycled glucose from lactic acid/AA/glycerol)

Question 5

Definition
Location
Function of glycolysis

Answer 5

Glucose (C6) => 2 pyruvate (C3)
Cytosol of all tissues
ATP synthesis (intermediate for fat, AA synthesis)

Question 6

4 stages of glycolysis

Answer 6

Activation with ATP
Splitting 6C sugar in half
Oxidation by removal of 2H
Atp synthesis

Question 7

Activation of glucose (R1-3)

Answer 7

D glucose =hexokinase/glucokinase (only found in liver) ATP=> Glucose 6 phosphate + ADP

Glucose 6 phosphate <=phosphoglucose isomerase=> fructose 6 phosphate

Fructose 6 phosphate = phosphofructokinase ATP=> fructose 1,6 biphosphate

Net loss of 2 ATP

Question 8

Reaction 1

Answer 8

D glucose =hexokinase/glucokinase ATP=> glucose 6 phosphate + ADP

Charge glucose to keep it in the cell

Question 9

Reaction 2

Answer 9

Glucose 6 phosphate <=phosphaglucose isomerase=> fructose 6 phosphate

Aldehyde => ketone
Ketones are more reactive

Question 10

Reaction 3

Answer 10

Fructose 6 phosphate =phosphofructokinase ATP=> fructose 16 biphosphate + ADP

Question 11

Splitting of 6C sugar to 3C units (Reaction 4-5)

Answer 11

Fructose 16 biphosphate ==> glyceraldehyde 3 phosphate + dihydroxyacetone phosphate

Triose phosphate isomerase can convert between the 2 products

Aldolase A can convert between products and fructose 16 biphosphate

Question 12

Oxidation step (Reaction 6)

Answer 12

Glyceraldehyde 3 phosphate =glyceraldehyde 3 phosphate dehydrogenase NAD+ Pi=> 1 3 biphosphoglycerate + NADH + H+

Question 13

Reaction 6

Answer 13

Glyceraldehyde 3 phosphate =glyceraldehyde 3 phosphate dehydrogenase NAD+ Pi=> 1 3 biphosphoglycerate + NADH + H+

Building energy into the molecule without ATP via oxidation

Question 14

Role of NAD as an H acceptor

Answer 14

(oxidation) NAD+ + H+ + 2e- <=> NADH (reduction)

Question 15

ATP synthesis steps (Reaction 7-10)

Answer 15

1 3 biphosphoglycerate <=phosphoglycerate kinase ADP=> 3 phosphoglycerate + ATP

3 phosphoglycerate <=Phosphoglycerate mutase => 2 phosphoglycerate

2 phosphoglycerate <=enolase=> phosphoenol pyruvate + H2O

Phosphoenolpyruvate =pyruvate kinase ADP=> pyruvate + ATP

Question 16

Reaction 7

Answer 16

1 3 biphosphoglycerate <=phosphoglycerate kinase ADP=> 3 phosphoglycerate + ATP

1 removed PO4 3-, added to ADP

Question 17

Reaction 8

Answer 17

3 phosphoglycerate <=Phosphoglycerate mutase => 2 phosphoglycerate

PO4 3- close to -ve charge

Question 18

Reaction 9

Answer 18

2 phosphoglycerate <=enolase=> phosphoenol pyruvate + H2O

Reduction
Activates PO4 3-

Question 19

Reaction 10

Answer 19

Phosphoenolpyruvate =pyruvate kinase ADP=> pyruvate + ATP

Removes PO4 3-, added to ADP

Question 20

Yield of ATP from glycolysis

Answer 20

Early stages use 2 ATP
Later stages make 4 ATP
Net yield of 2ATP

Question 21

What happens during anaerobic glycolysis

Answer 21

Pyruvate is not metabolized to CO2
Pyruvate converted to lactate, convert NADH => NAD+

Pyruvate + NADH + H+ => NAD+ + lactate

Question 22

Reaction catalyses by lactate dehydrogenase

Answer 22

Pyruvate =(muscle NADH + H+)=> L lactate + NAD+

L lactate =(liver NAD+)=. Pyruvate + NADH + H+

When lactate formed, NADH can be oxidized to regenerate NAD+ H+

Question 23

Specialized function of glycolysis in tissues

Answer 23

Skeletal muscle, ATP production during intense exercise
RBC, can only undertake glycolysis, no mitochondria
Brain, major source of ATP (fats cannot be converted into fuel)

Question 24

Regulation of glycolysis

Answer 24

Increase rate of glycolysis by
intense muscle work and exercise
after high carbohydrate meal (increased insulin)

Decrease rate of glycolysis
fasting (increased plasma glucagon)

Question 25

Feedback inhibition of metabolic pathways

Answer 25

Allosteric control of phosphofructokinase in R3
Activator 
  AMP
Inhibitory
  ATP
  Citrate