glycolysis Flashcards
what is hypoglycaemia?
too little glucose in the blood
what is hyperglycaemia?
too much glucose in the blood
how much glucose is currently circulating in the blood?
4g
what % of blood glucose is used by the brain at rest?
60%
how many glucose transporters in the human genome?
14
what is Km?
the concentration at which something is saturated
where is GLUT1 found and what Km does it have?
found in all cells
low Km
where is GLUT2 found and what Km does it have?
found in liver and pancreas
high Km
why is it important that GLUT2 has a high Km?
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
where is GLUT4 found and what Km does it have?
muscles and adipose tissue
Low Km
where is GLUT4 found in the cell?
in vesicles in the cytoplasm
fused with the membrane
what controls the location of GLUT4?
exercise and insulin
what effect does insulin have on GLUT4?
insulin causes GLUT4 to be recruited into the membrane
is hexokinase sensitive to feedback inhibition?
yes
is glucokinase sensitive to feedback inhibition?
no
how is glucokinase different to hexokinase?
glucokinase found in the liver and pancreas, hexo found everywhere else
gluco has a higher Km
gluco isn’t sensitive to feedback inhibition
what controls the location of glucokinase and how?
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
define isomerisation
rearranging the molecule to rearrange the energy
is the conversion of Glucose-6-phosphate to fructose-6-phosphate reversible?
yes
is fructose-6-phosphate –> fructose-1,6-bisphosphate reversible?
no
how is fructose-6-phosphate –> fructose-1,6-bisphosphate controlled?
substrates - ATP:AMP ratio and citrate
phosphorylation of regulatory subunit
what does phosphofructokinase 2 do?
acts on fructose-6-phosphate to form fructose-2,6-bisphosphate when the level of fructose-6-phosphate is too high
how is NADH converted back to NAD in aerobic and anaerobic conditions?
aerobic - ETC
anaerobic - forming lactate from pyruvate using pyruvate dehydrogenate
what pH is lactate?
acidic
what happens if lactate builds up in the muscle?
causes muscle pain
what happens in NADH builds up?
glycolysis stops bc limited amount of NAD
where is glycerol metabolised?
liver
how is glycerol metabolised in the liver?
Glycerol kinase converts glycerol –> glycerol 3P –> dihydroxyacetone phosphate
what is the net ATP gain from glycerol?
2 ATPs per glycerol
but 1 is used
so net output is 1
how can fructose feed into glycolysis?
- 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
why is pentose phosphate important?
important in biosynthesis
creating NADPH from glucose-6-phosphate needed for fat and steroid hormone synthesis
nucleotide biosynthesis
what are the products of the pentose phosphate pathway?
fructose-6-phosphate and glyceraldehyde-3-phosphate
