respiration Flashcards
define respiration
the process whereby organic molecules are oxidised to release chemical potential energy for the synthesis of ATP
what are the 2 methods of ATP synthesis?
substrate-level phosphorylation and oxidative phosphorylation
function of coenzymes NAD+ and FAD+
act as electron acceptors and donors that transfer electrons from substrates to ETC
what is the structure-function relationship of the inner mitochondrial membrane?
the inner mitochondrial membrane is extensively folded into cristae projecting inwards towards the matrix=> providing a large surface area for the attachment of electron carriers, enzymes and ATP synthase
site of accumulation of H+
intermembrane space
direction of diffusion of H+
from intermembrane space to the matrix
site of glycolysis
cytosol
outline the process of glycolysis
- phosphorylation of hexose
->glucose is phosphorylated by ATP into glucose-6-phosphate
->glucose-6-phosphate is converted into fructose-6-phosphate
->fructose-6-phosphate is phosphorylated by ATP into fructose-1,6-bisphosphate - cleavage of 6C sugar bisphosphate
->fructose-1,6-bisphosphate is cleaved into 2 triose phosphate molecules (3C)
3.triose phosphates are converted into pyruvate
->oxidation occurs and 2 NADH are synthesized
->substrate-level phosphorylation also occurs producing 4 ATP
-> net 2 ATP produced
requirements for glycolysis (reactants)
1 glucose, 4 ADP, 2 NAD+
products of glycolysis
2 pyruvate, 2 ATP, 2 NADH
name the enzyme which catlayzes the phosphorylation of glucose into glucose-6-phosphate
hexokinase
hexokinase is allosterically inhibited by…
its product glucose-6-phosphate
name the enzyme which catalyzes the phosphorylation of fructose-6-phosphate into fructose-1,6-bisphosphate
phosphofructokinase (PFK1)
PFK1 is allosterically inhibited by…
ATP
outline the process of link reaction
1.pyruvate is decarboxylated releasing one CO2 this is catalysed by pyruvate decarboxylase
2. NAD+ is reduced to NADH
3. the remaining 2C compound combines with coenzyme A to form acetyl-CoA
site of link reaction
matrix of the mitochondria
requirements of link reaction (reactants)?
2 pyruvate, 2 NAD+, 2 coenzyme A
products of link reaction?
2 acetyl CoA, 2 NADH, 2CO2
outline the process of the Krebs cycle
- acetyl-CoA combines with oxaloacetate to form citrate
- citrate undergoes oxidative decarboxylation to form a-ketoglutarate
-> 1 NAD+ is reduced to NADH
-> 1CO2 is released
3.a-ketoglutarate undergoes oxidative decarboxylation to form succinyl CoA
-> 1 NAD+ is reduced to NADH
-> 1CO2 is released - succinyl CoA undergoes substrate-level phosphorylation to form succinate
-> 1 ATP is produced - succinate is oxidised into malatate
-> 1 FADH+ is reduced to FADH2
6.malatate is oxidised and rearrranged to regenerate oxaloacetate
-> 1NAD+ is reduced to NADH
requirements for Krebs cycle (reactants) for one molecule of glucose?
2 acetyl-CoA, 6NAD+, 2 FAD+, 1 ADP
products of the Krebs cycle?
2 oxaloacetate, 4CO2, 6NADH, 2FADH2, 2ATP
what are the components in Krebs cycle? (total 7)
acetyl-CoA + oxaloacetate-> citrate->a-ketoglutarate->succinyl-CoA-> succinate-> malatate->regenerates oxaloacetate
how many turns of the Krebs cycle per glucose molecule?
2 turns-> 2 pyruvate required-> 2 oxaloacetate
outline the process of oxidative phosphorylation
- NADH and FADH2 donate electrons to electron carriers of ETC
2.electrons are passed down electron carriers of decreasing energy levels - electrons are then passed down to the final electron acceptor O2 (to form water)
- energy released from the flow of electrons is used to pump H+ from the matrix into the intermembrane space
- this creates a steep proton gradient as the inner membrane of the mitochondria is impermeable to ions resulting in the accumulation of H+ in the intermembrane space
6.diffusion of H+ from the intermembrane space into the matrix down a concentration gradient via the hydrophilic channel of ATP synthase releases energy - which is coupled with ATP synthesis catalysed by ATP synthase
site of oxidative phosphorylation
inner membrane of mitochondria
what is the purpose of lactate and alcohol fermentation as processes in anaerobic respiration?
to regenerate NAD+ such that glycolysis can continue to occur to produce ATP
how many ATP molecules are produced in oxidative phosphorylation of one glucose molecule?
oxidation of 1 NADH produces 3 ATP while
oxidation of 1 FADH2 produces 2 ATP
->10 NADH total (2 glycolysis, 2 link reaction, 6 Krebs cycle)=30 ATP
->2 FADH2 total (Krebs cycle)=4 ATP
->total ATP produced oxidative phosphorylation of one glucose molecule= 34 ATP
outline the process of lactate fermentation
- pyruvate is reduced into lactate, catalysed by lactate dehydrogenase
- NAD+ is regenerated for glycolysis to continue to occur
outline the process of alcohol fermentation
- pyruvate is decarboxylated to form ethanal, catalysed by pyruvate decarboxylase
- ethanal is reduced to ethanol, catalysed by alcohol dehydrogenase
- NADH is oxidised to NAD+
- NAD+ is regenerated for glycolysis to continue to occur
name the enzyme which catalyses the reduction of pyruvate into lactate
lactate dehydrogenase
name the enzyme which catalyses the decarboxylation of pyruvate to ethanal
pyruvate decarboxylase
name the enzyme which catalyses the reduction of ethanal into ethanol
alcohol dehydrogenase
total number of ATP produced during aerobic respiration
10 NADH= 30 ATP
2 FADH2=4 ATP
2 ATP from glycolysis
2 ATP from Krebs cycle
=> 38 ATP produced
