Kreb's cycle

Kreb’s cycle

— Also known as Citric acid cycle

— Other name is tricarboxylic Acid Cycle

— Generates energy before proceeding to the electron transport chain

— Oxidation of Acetyl-CoA to produce energy

— Synthesis and breakdown of NADH (Nicotinamide Adenine Dehydrogenase)

— Production of amino acids

Mitochondria

— Where kreb’s cycle is located

— For eukaryotes (powerhouse of the cell suspended in the cytoplasm)

Cytosol

— Where kreb’s cycle is located

— For prokaryotes

Acetyl-CoA → Citrate (6 carbons)

Enzyme: Synthase

Citrate → Isocitrate (6 carbons)

— Enzyme: Isocitrate dehydrogenase

— Product: NAD⁺ → NADH: CO₂ released

α-Ketoglutarate → Succinyl-CoA (4 carbons)

— Enzyme: α-Ketoglutarate dehydrogenase

— Product: NAD⁺ → NADH

Succinyl-CoA → Succinate

— Enzyme: Succinyl-CoA synthase

— Produces Guanosine Triphosphate (GTP) (converted to ATP)

Succinate → Fumarate

Enzyme: Succinate dehydrogenase

Product: Flavine Adenine Dehydrogenase (FAD) → FADH₂

Fumarate → Malate

— Enzyme: Fumarase

— Product: Do not generate anything

Malate → Oxaloacetate

— Enzyme: Malate dehydrogenase

— Product: NAD⁺ → NADH

Oxaloacetate → Citrate

Enzyme: Citrate synthase

NADH

— 3 × 2 = 6

FADH₂:

— 1 × 2 = 2

GTP (ATP):

— 1 × 2 = 2

CO₂:

— 2 × 2 = 4

Glycolysis

— Glucose → 2 Pyruvate

Glycogenesis

— Glucose → Glycogen

Glycogenolysis

— Glycogen → Glucose

Lipolysis

— TAG → Glycerol + Fatty Acids (FA)

Lipogenesis

— FA + Glycerol → TAG

Cholesterol synthesis

— Acetyl-CoA → Cholesterol

Ketogenesis

— Acetyl-CoA → Ketone Bodies

Transamination

— AA + Ketoacids → Ketoacids + AA

Oxidative deamination

— AA → Ketoacids or NH₃

Ketolysis

Ketone → Acetyl-CoA