respiration qp1 PMT Flashcards
Why does aerobic respiration yield fewer ATP molecules than the theoretical maximum
-protons leak out of the outer mitochondrial membrane and into the cytoplasm
-ATP is needed to actively transport pyruvate into the mitochondria
-not all proton movement is sued to generate ATP
-some ATP is used to actively transport H+ from (reduced) NAD formed in glycolysis into the mitochondria
-some energy in ETC is not used to transport H+ and is released as heat
-not all reduced NAD is used to feed into the ETC
Why does anaerobic reparation produce less atp than aerobic respiration
-anaerobic respiration occurs via glycolysis
-glycolysis produces a net of 2 ATP molecules
-in anaerobic respiration, only substrate level phosphorylation takes place.
-Oxygen is not available as the final electron acceptor
-Krebs cycle and chemiosmosis/ oxidative phosphorylation do not occur.
-if there is not enough NAD, pyruvate will have to enter the lactate or ethanol fermentation pathway.
why can the anaerobic respiration pathway in animal cells be reversed while why cant the anaerobic respiration pathway in yeast cells not be reversed
-ethanal is converted to ethanol via reduced NAD and aided by ethanol dehydrogenase, CO2 is lost and carboxylase can not reverse the reaction.
-the lactate fermentation pathway can be reversed as no atoms are lost and lactate dehydrogenase can reverse the pathway
why is lactate converted to pyruvate in liver cells
-hepatocytes can tolerate the low pH
- hepatocytes have enzyme to metabolize lactate/ catalyze this reaction.
-conversion of lactate requires oxygen and oxygen is not available during reparation in respiring cells but is sufficient in hepatocytes
what might happen if a persons liver didnt break down insulin
-blood glucose conc would fall
-glucose would continue to be taken up by cells/ liver/muscle
-would store too much glucose to glycogen
-mitochondria cant generate enough ATP as less glucose available in blood
-coma/death
*alcohol results in excess reduced NAD, this causes:
-inhibition of lactate to pyruvate
-inhibiting fatty acid oxidation
-promoting fatty acid synthesis
what are the consequences of liver metabolism if someone has a regular high alcohol intake
-build up of lipids leading to cirrhosis
-fat deposits increase
-build up of lactate/ prevention of pathways/ poison’s or kills liver cells
-lack of oxidized NAD for reactions
-disruption of enzymes due to low ph
-lack of substrate/ fatty acid available for respiration
-some deamination/ ornithine cycle cannot occur
