Lecture 3 Flashcards
What determines the fates of pyruvate?
availability of oxygen
true of false; fermentation allows glycolysis to proceed in the absence of oxygen?
true
Where does pyruvate go if oxygen is present?
mitochondria where is converted to acetyl coa by pyruvate dehydrogenase
When is the route of pyruvate to the mitochondria most favoured?
elevated levels of acetyl CoA in the mitochondria
What is fate 1
the conversion of pyruvate to ethanol
What conditions is fate 1 under
anaerobic
eg. in yeast (by product of ethanol and CO2)
What is fate 2
conversion of pyruvate to lactate
What are the conditions of fate 2
in animals where demand for ATP outweighs production in mitochondria (anaerobic)
true or false; even in fully oxygenated resting muscle cell about half of glucose which enters glycolysis is converted to lactate
true
what do you call the process in which: lactate is transferred from muscle to the liver; and the transfer of glucose from liver to muscle
cori cycle
What is fate 3
pyruvate/ alanine cycle
what are the conditions of pyruvate/alanine cycle
- pyruvate generated in muscle and other tissues can be converted to alanine
- then returned to liver ( converted to pyruvate; used as gluconeogenic substrate; or oxidized in the TCA cycle) for gluconeogenesis
- requires alpha amino acid to be a donor of an amino group
significance of the pyruvate alanine cycle
indirect way for the muscle to get ride of nitrogen; while replenishing its energy supply
What does the pyruvate/alanine cycle allow for the non hepatic tissues?
allows non hepatic tissues to deliver the amino portion of catabolized amino acids to the liver for excretion as urea in the kidneys
What is fate 4
conversion of pyruvate to oxaloacetate
true or false; fate 4 is the first step of gluconeogenesis
true; involves the carboxylation of pyruvate by pyruvate carboxylase to oxaloacetate
where does fate 4 occur
mitochondria
what does fate 4 use?
carboxylated biotin factor as the CO2 source
ATP as the free energy source
Why is fate 4 important?
when the cell has too much acetyl CoA; more than needed to supply the TCA cycle; acetyl CoA activates pyruvate carboxylase in an allosteric manner and diverts pyruvate to oxaloacetate production
What is fate 5
conversion of pyruvate to acetyl CoA
What are the conditions for fate 5
anaerobic
multi enzyme complex pyruvate dehyrogenase converts pyruvate to acetyl CoA
Where is fate 5
inside the mitochondria
true or false; fermentation allows for NAD+ to be regenerated
true ( glycolysis and ATP production can then proceed without the involvement of oxygen)
true or false: when oxygen is present, additional ATP can be generated when NADH delivers its electrons to the electron transport chain; regardless of the presence of O2 glycolysis will continue
true
what gluconeogenesis and where does it occur?
in the liver
- reversal of glycolysis
what is the role of the liver to the muslce
to supply the muscle with fresh incomming glucose so glycolysis and energy production can keep going
What does alanine serve as
carrier of ammonia
Why does alanine inhibit pyruvate kinase
alanine is used to make glucose from pyruvate; it is therefore not desirable to pyruvate kinase active under these conditions as it would regenerate pyruvate
