biochemistry 1 Flashcards
what is the first stage of glycolysis called
energy investment
what is the second stage of glycolysis called
energy generation
what converts glucose into glucose 6 phosphate
glucokinase or hexokinase
and ATP
where is glucokinase found
liver and pancreas
what converts glucose-6phosphate to fructose-6- phosphate
phosphoglucose isomerase
what converts glucose-6-phosphate to fructose-1,6-bisphosphate
phosphofructokinase-1
and ATP
what converts fructose-1,6-bisphophate to glyceraldehyde-3-phosphate
aldolase
what converts fructose-1,6-bisphosphate to dihydroxyacetone phosphate
aldolase
what converts dihydroxyacetone phosphate to glyceraldehyde-3-phosphate
triose phosphate isomerase
why is there phosphorylation in the energy investment stage
- destabilisation of carbon-carbon bonds
what converts glyceraldehyde-3-phsopahte t0 1,3-bisphosphoglycerate
glyceraldehyde-3-phosphate dehydrogenase and NAD+
what converts 1,3-bisphosphoglycerate to 3-phosphoglycerate
phosphoglycerate kinase and ADP
what converts 3-phosphoglycerate to 2-phosphoglycerate
phosphoglycerate mutase
what converts 2-phophoglycerate to phosphoneolpyruvate
- H20
enolase
what converts phosphoneolpyruvate to pyruvate
pyruvate kinase and ADP
how many ATP are produced from anaerobic glycolysis
2
how many ATP are produced from aerobic glycolysis
7
how many ATP are produced from aerobic respiration
32
what is hexokinase inhibited by
glucose-6-phosphate
what is phosphofructokinase-1 inhibited by
ATP and citrate
what is phosphofructokinase-1 activated by
AMP,fructose-2,6-bisphosphate
what is pyruvate kinase inhibited by
ATP and alanine
what is private kinase activated by
AMP and fructose-1,6-bisphosphate
where is hexokinase found at what is its functions
- normal energy requiring tissue eg. muscles
- low Km so is saturated at low glucose levels
- regulated by G6P negative feedback
describe the Km, regulation and function
- Km is higher so high capacity of glucose
- no feedback from G6P
- glucose sensing in the pancreas and reduce glycolysis in the liver for glycogen synthesis
what does insulin do to glycolysis
increases glycolysis buy inducing hexokinase, phopshofructokinase-1 and pyruvate kinase
- stimulates glucose uptake in blood
what does the muscle, liver and adipose do when there is insulin released
muscle and liver - converts glucose to glycogen
liver - decrease glyconeogenesis
adipose - increases fat synthesis to act on hypothalamus to decrease appetite
what does the release of glucagon do to glycolysis
- decrease glycolysis
- represses hexokinase, phosphofructokinase-1 and pyruvate kinase
what does the release of glucagon do to the muscle and liver
muscle and liver - stimulates glycogen breakdown
liver - stimulates gluconoegenesis
what happens in aerobic conditions to NAD+ recovery
- NADH not oxidised in electron transport chain
- NADH build up
- pyruvate reduced to lactate by lactate dehydrogenase
- NAD+ used for glycolysis
describe the cori cycle
1) glycolysis in the muscles coverts glucose to lactate
2) lactate is transported to the liver via blood
3) gluconeogenesis in liver reforms glucose from lactate
4) glucose transported back to muscles via blood
when does the cori cycle take place
- under anaerobic conditions
- liver resupplies muscles with glucose and maintains normal blood glucose levels
what is lactic acidosis and what are the symptoms
- lactic acid build up in blood stream >4mM
- symptoms - nausea, vomiting, weakness
what is lactic acidosis causes by
- decrease O2 delivery to tissue
- decrease lactate clearance - liver disease and sepsis
- increase lactate production - cancer
describe the manose cycle
- mannose —> mannose-6- phosphate - hexokinase and ATP
- mannose-6-phosphate –> fructose-6-phosphate - phopshomannose isomerase
- glycolysis continues
what cause lactose intolerance
- no lactase
- increased osmotic pressure
- bacterial fermentation
- causes diarrhoea
what causes fructose intolerance
- no GLUT5 carrier protein
- increases osmotic pressure
- diarrhoea
what are the two stages of the pentose shunt
- oxidative phase
- non-oxidative phase
what does the pentose shunt produce
- NADPH
- ribose-5-phosphate
- fructose-6-phospahte
what is the oxidative phase of the pentose shunt dependent on
- availability of NADP+
what is the non oxidative phase of the pentose shunt dependent on
- availability of substrates
when is the non oxidative phase of the pentose shunt active
- when ribose-5-phosphate is required more than NADP
when is the oxidative phase of the pentose shunt active
- when ribose-5-phosphate and NDPH are required equally
what occurs when NADPH is required more than ribose-5-phosphate in the pentose shunt
- fructose-6-phosphate and glyceraldehyde-3-phosphate are converted back into glucose-6-phosphate by phosphoglucose isomerase and glyceraldehyde phosphate dehydrogenase
- glucose may be converted into pyruvate
what are the causes, symptoms and triggers for 6-GPD deficiency
causes - X-linked recessive, major cause of haemolytic anaemia
symptoms - dark urine, fatigue, painless, rapid heart rate, shortness of breathe, jaundice
triggers - foods, medicine, bacterial or virus infections
what is used to measure vitamin B - thiamine levels
- erythrocyte transketolase assay
what enzymes is vitamin B1 - thiamine used in
- pyruvate dehydrogenase
- transketolase activity
