adaption to exercise

Question 1

a. explain the basis of the increased energy demands during exercise

Answer 1

During exercise ATP is needed by the muscles in order to contract, in order for this ATP to be produced aerobic respiration must occur in the mitochondria of the muscles:

Question 2

b. compare aerobic and anaerobic respiration in terms of product yield

Answer 2

Aerobic respiration is far more energy-efficient than anaerobic respiration. Aerobic processes produce up to 38 ATP per glucose. Anaerobic processes yield only 2 ATP per glucose.

Question 3

c. explain the regulation of glycolysis, the tricarboxylic acid cycle, oxidative phosphorylation and lactic acid production

Answer 3

Glycolysis–creates ATP through substrate level phosphorylation and also converts glucose into pyruvate (releasing 2 molecules of ATP)This pyruvate is then used in the link chain reaction, where pyruvate is converted in acetyl-coenzyme AThis then enters the Krebs cycle which produces 3 moleculesof NADH and 1 molecule of FADH2These electron carrier molecules then undergo oxidative phosphorylation where they pass of an electron to the electron transport chain so ATP can be synthesisedThis ATP is then used for the muscle to contractAfter a while anaerobic respiration must occur, this is where there is no more oxygen available for it to be the terminal acceptor molecule of the electron transport chain.Therefore, pyruvate is converted into lactic acid, one molecule of NAD and ATPIf all glucose is used up then glycogenolysis (breakdown of glycogen to give glucose) and gluconeogenesis(generation of glucose from lactate, glycerol and amino acids) will be able to supply the mitochondria with glucose/pyruvate

Question 4

c. explain the regulation of glycolysis,

Answer 4

Glycolysis–creates ATP through substrate level phosphorylation and also converts glucose into pyruvate (releasing 2 molecules of ATP)

This pyruvate is used in the link chain reaction, pyruvate is converted in acetyl-coenzyme A

This then enters the Krebs cycle which produces 3 molecules of NADH and 1 molecule of FADH2

These electron carrier molecules then undergo oxidative phosphorylation where they pass of an electron to the electron transport chain so ATP can be synthesised

This ATP is then used for the muscle to contract After a while anaerobic respiration must occur- no oxygen available for it to be the terminal acceptor molecule of the electron transport chain.

Therefore, pyruvate is converted into lactic acid, one molecule of NAD and ATP If all glucose is used up then glycogenolysis (breakdown of glycogen to give glucose) and gluconeogenesis(generation of glucose from lactate, glycerol and amino acids) will be able to supply the mitochondria with glucose/pyruvate

Question 5

d. explain the fate of lactic acid produced by anaerobic respiration

Answer 5

Lactate is transported to metabolically active cells, such as in the heart and brain. Here it is converted back to pyruvate, which is then utilised in the Krebs cycle.

The Cori cyclerefers to the metabolic pathway in which lactate produced by anaerobic glycolysis in the muscles moves to the liver and is converted to glucose

The lactate is hydrolysed by lactate dehydrogenase in the liver and then converted into 2 x pyruvate

The pyruvate is converted into glucose by gluconeogenesis so that this glucose in turn can be converted into glucagon to maintain a constant level of glucose (this only happens when glucose is in plentiful supply)

Question 6

e. describe the importance of cofactors and coenzymes in cellular respiration