ch. 18.1: carbohydrates metabolism

define metabolism

the sum of the chemical processes in living cells by which energy and nutrients are provided for vital processes and activities & new materials are assimilated

define anabolism

constructive of metabolism involving synthesis, occurs while the animal is growing

define catabolism

destructive part of metabolism involving the release of energy & breakdown of complex materials, occurs while the animal is losing weight

what are the 4 things that metabolism of CHO provides

1) energy source (ATP and heat)

2) short term energy storage (glucose)

3) long-term energy storage (excess CHOs are stored as fats and glycogen)

4) amino acid precursor (amino groups can be added to carbon skeletons that are provided by CHOs and made into amino acids)

what are the 3 systems of importance with CHO metabolism

1) glycolysis

2) krebs cycle (TCA cycle)

3) oxidative phosphorylation

where do glycolysis, TCA cycle, and oxidative phosphorylation occur and is oxygen required?

1) glycolysis: anaerobic, in cytosol

2) krebs cycle: aerobic, in mitochondria

3) oxidative phosphorylation: aerobic, in mitochondria

what is the purpose of glycolysis, krebs cycle, and oxidative phosphorylation?

to oxidize glucose & generate ATP

i.e. GENERATE METABOLIC FUEL (energy)

what is the net yield of ATP and NADH in glycolysis

• grossly generates:

  • 4 ATP

  • 2 NADH

• uses 2 ATP initially (to split glucose)

• NET YIELD of ONE molecule of glucose:

  • 2 ATP

  • 2 NADH (equivalent to 3 ATP each)

  • 2 pyruvates

what is net yield of ATP ONLY in glycolysis

8 ATP

how much ATP is yielded from one NADH molecule

3

how much ATP is yielded from one FADH2 molecule

2

what is the net yield of molecules from 1 acetyl-CoA molecule entering the krebs cycle

• 1 NADH (from pyruvate → acetyl CoA)

• 3 NADH

• 1 FADH2

• 1 GTP

how much ATP is produced in the krebs cycle (+ pyruvate converted to acetyl-CoA)

15 per one pyruvate molecule

30 total for one glucose molecule

what is the total net yield of ATP from glycolysis and the krebs cycle

38

what is the tally for ATP from glycolysis and the krebs cycle

glycolysis: 8 (2 ATP + 2 NADH)

krebs: 30 ( x2 (4 NADH + 1 FADH2 + 1 GTP))