Unit 5 - Respiration

Mitochondria (mostly)

• Glycolysis • Link Reaction • Krebs Cycle • Oxidative Phosphorylation

Cytoplasm

• Glucose is phosphorylated by the hydrolysis of 2 ATP molecules to form glucose phosphate • Glucose Phosphate is split into 2TP molecules • TP is oxidised (a hydrogen is removed from each TP molecule) and the hydrogen is used to reduce NAD (forms NADH) • TP is converted to pyruvate and 4ATP molecules are formed in the process (through substrate-level phosphorylation, TP donates its phosphate to ADP) • Pyruvate is actively transported to mitochondrial matrix ONLY IF O₂ is present

• Net gain of 2ATP • 2 Pyruvate • 2 NADH

• Glycolysis is a universal process that takes place in almost all living organisms • Enzymes for this process are all located in the cytoplasm • Glycolysis doesn’t require any organelles or membranes

Mitochondrial Matrix

• Pyruvate is decarboxylated (loses a CO₂ molecule) • CO₂ diffuses out of the mitochondria as a waste product • Pyruvate is oxidised and loses a hydrogens (accepted by NAD to form NADH) to form acetate (a 2C molecule) • Acetate binds to coenzyme A to form acetylcoenzymeA

• 1 AcetylcoenzymeA • 1 NADH • 1 CO₂ (waste product)

Mitochondrial Matrix

• Acetyl (2C) is accepted by oxaloacetate (4C) from CoA to form citrate (6C) • Citrate is decarboxylated and oxidised (NAD is reduced, forms NADH) to form a 5C molecule • The 5C molecule is decarboxylated again and then oxidised 3 more times (2NADH and 1FADH₂ are formed from the reduction of 2NAD and 1FAD) • ATP is also synthesised from ADP and P(i)

• 1ATP • 2CO₂ • 3NADH • 1FADH₂ • HOWEVER the Krebs cycle turns 2X per 1 glucose molecule so if asked about this, double the products above

Inner Mitochondrial Membrane

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