glycolysis

Question 1

what is hypoglycaemia?

Answer 1

too little glucose in the blood

Question 2

what is hyperglycaemia?

Answer 2

too much glucose in the blood

Question 3

how much glucose is currently circulating in the blood?

Answer 3

4g

Question 4

what % of blood glucose is used by the brain at rest?

Answer 4

60%

Question 5

how many glucose transporters in the human genome?

Answer 5

14

Question 6

what is Km?

Answer 6

the concentration at which something is saturated

Question 7

where is GLUT1 found and what Km does it have?

Answer 7

found in all cells

low Km

Question 8

where is GLUT2 found and what Km does it have?

Answer 8

found in liver and pancreas

high Km

Question 9

why is it important that GLUT2 has a high Km?

Answer 9

Pancreas must detect glucose levels – if pancreas is easily saturated then it cannot detect high glucose levels.
Liver plays a role in glucose homeostasis – should be able to take up glucose when glucose levels are high

Question 10

where is GLUT4 found and what Km does it have?

Answer 10

muscles and adipose tissue

Low Km

Question 11

where is GLUT4 found in the cell?

Answer 11

in vesicles in the cytoplasm

fused with the membrane

Question 12

what controls the location of GLUT4?

Answer 12

exercise and insulin

Question 13

what effect does insulin have on GLUT4?

Answer 13

insulin causes GLUT4 to be recruited into the membrane

Question 14

is hexokinase sensitive to feedback inhibition?

Answer 14

yes

Question 15

is glucokinase sensitive to feedback inhibition?

Answer 15

no

Question 16

how is glucokinase different to hexokinase?

Answer 16

glucokinase found in the liver and pancreas, hexo found everywhere else

gluco has a higher Km

gluco isn’t sensitive to feedback inhibition

Question 17

what controls the location of glucokinase and how?

Answer 17

GKRP
when glucose levels are low, glucokinase is bound to GKRP in the nucleus.
when glucose levels are high, glucokinase is released into the cytoplasm

Question 18

define isomerisation

Answer 18

rearranging the molecule to rearrange the energy

Question 19

is the conversion of Glucose-6-phosphate to fructose-6-phosphate reversible?

Answer 19

yes

Question 20

is fructose-6-phosphate –> fructose-1,6-bisphosphate reversible?

Answer 20

no

Question 21

how is fructose-6-phosphate –> fructose-1,6-bisphosphate controlled?

Answer 21

substrates - ATP:AMP ratio and citrate

phosphorylation of regulatory subunit

Question 22

what does phosphofructokinase 2 do?

Answer 22

acts on fructose-6-phosphate to form fructose-2,6-bisphosphate when the level of fructose-6-phosphate is too high

Question 23

how is NADH converted back to NAD in aerobic and anaerobic conditions?

Answer 23

aerobic - ETC

anaerobic - forming lactate from pyruvate using pyruvate dehydrogenate

Question 24

what pH is lactate?

Answer 24

acidic

Question 25

what happens if lactate builds up in the muscle?

Answer 25

causes muscle pain

Question 26

what happens in NADH builds up?

Answer 26

glycolysis stops bc limited amount of NAD

Question 27

where is glycerol metabolised?

Answer 27

liver

Question 28

how is glycerol metabolised in the liver?

Answer 28

Glycerol kinase converts glycerol --> glycerol 3P --> dihydroxyacetone phosphate

Question 29

what is the net ATP gain from glycerol?

Answer 29

2 ATPs per glycerol but 1 is used so net output is 1

Question 30

how can fructose feed into glycolysis?

Answer 30

- metabolised by hexokinaseto form F6P - metabolised by fructokinase in the liver to make F1P. acted on by aldolose B to form glyceraldehyde (+dihydroxyacetone phosphate) to make G3P

Question 31

why is pentose phosphate important?

Answer 31

important in biosynthesis creating NADPH from glucose-6-phosphate needed for fat and steroid hormone synthesis nucleotide biosynthesis

Question 32

what are the products of the pentose phosphate pathway?

Answer 32

fructose-6-phosphate and glyceraldehyde-3-phosphate