Glycolysis

Question 1

what is metabolism and what are its components?

Answer 1

all chemical reactions that maintain the living state of cells and organisms
anabolism
catabolism

Question 2

where does energy in the body come from?

Answer 2

ultimately all from the sun
plants use sun to synthesise macromolecules > catabolic pathways oxidise macromolecules creating ATP > ATP used to drive biosynthetic reactions

Question 3

when does anabolism and catabolism occur in ATP synthesis?

Answer 3

glycolysis = anabolism
krebs = catabolism

Question 4

in what form is glucose found plants and animals?

Answer 4

plants = starch and cellulose
anaimals = glycogen

Question 5

what is the body’s primary energy source?

Answer 5

glucose

oxidised to CO2 and H2O

Question 6

name 2 polysaccharides

Answer 6

cellulose

glycogen

Question 7

what are the possible fates of glucose?

Answer 7

1. glycogen, starch, sucrose, conversion to lipids (storage)
2. becomes ribose 5 phosphate (oxidation via pentose phosphate pathway)
3. Becomes lactate (fermentation by anaerobic glycolysis)
4. Becomes pyruvate (via oxidation in glycolysis)

Question 8

stage 2 of metabolism?

Answer 8

acetyl CoA production via glycolysis

Question 9

stage 3 of metabolism?

Answer 9

acetyl CoA oxidation via krebs cycle

Question 10

what happens after stage 3 of metabolism?

Answer 10

electron transfer and oxidative phosphorylation

Question 11

how does glucose enter cells?

Answer 11

via Na+/glucose symporters

via passive facilitated diffusion glucose transporters (GLUT 1-5)

Question 12

how does GLUT 1 function?

Answer 12

glucose binds causing a conformational change
binding site faces inwards
glucose can be released inside
conformational change regenerates the binding site in the outside

Question 13

describe the overall reaction of glycolysis

Answer 13

glucose > fructose-1,6-bisphosphate > 2 triose phosphates
> 2 pyruvates
2 ATP used
4 ATP made
2NAD+ > 2 NADH + 2H+

Question 14

what are the 3 stages of glycolysis?

Answer 14

stage 1 = glucose trapped and destabilised
stage 2 = 2 interconvertible 3C molecules formed (triose phosphates)
stage 3 = generation of ATP

Question 15

what are the 3 control points of glycolysis?

Answer 15

Hexokinase - controls substrate entry
Phosphofructokinase - controls rate of flow
Pyruvate kinase - controls product exit

Question 16

hexokinase controls substrate entry via what irreversible reaction?

Answer 16

glucose + ATP > glucose 6 phosphate + ADP + H+

Question 17

phosphofructokinase controls rate of flow via what reaction?

Answer 17

fructose 6 phosphate + ATP > fructose 1,6 bisphosphate + ADP + H+

Question 18

pyruvate kinase controls exit of product via what reaction?

Answer 18

phosphoenolpyruvate + ADP + H+ > pyruvate + ATP

Question 19

what activates/inhibits phosphofructokinase?

Answer 19

activators (increase glycolysis):
- AMP
- fructose 2,6 bisphosphate
inhibitors (decrease glycolysis):
- ATP
- citrate
- H+

Question 20

what is the energy charge of the cell?

Answer 20

ATP/AMP ratio
ATP present = charges
AMP = discharged

Question 21

how is AMP formed?

Answer 21

when ATP is used up,
ATP > ADP + Pi
adenylate kinase salvages some energy in ADP,
2ADP > ATP + AMP

Question 22

what happens if mitochondrial metabolism is inhibited by lack of oxygen?

Answer 22

NADH is used to ferment pyruvate to lactic acid (lactate)

NADH is regenerated at beginning of stage 3

Question 23

what is the Warburg effect?

Answer 23

up-regulation of anaerobic glycolysis in cancer cells

Question 24

cancer cells have a high Km hexokinase, true or false?

Answer 24

false, they have a low Km hexokinase

allows rapid energy production and growth, very high glucose demand as very inefficient

Question 25

why is knowledge of cancer cells’ high glucose demand useful?

Answer 25

can treat cancer by targeting glycolysis

• 2 Deoxy-glucose
• 3 Bromopyruvate
• Dichloroacetate (DCA)