18.2 glycolysis

glycolysis

glycolysis

• 1st stage of aerobic respiration, occurs in cell’s cytoplasm

• breaks glucose (6-carbon molecule) → 2 pyruvate molecules (3-carbon) through series of reactions involving specific enzymes

• doesn’t require oxygen = anaerobic process

describe the process of glycolysis

1. glucose phosphorylation - 2 ATP molecules donate phosphate groups to glucose, forming hexose bisphosphate.

2. lysis - hexose bisphosphate molecule split into 2 molecules of triose phosphate (TP)

3. phosphorylation of TP - 2nd phosphate group added to each TP molecule, converting them into 2 molecules of triose bisphosphate

4. dehydrogenation - hydrogen is removed from each triose bisphosphate molecule (they are oxidised) + used to form 2 reduced NAD, 2 pyruvate + 4 ATP molecules through substrate-level phosphorylation.

substrate-level phosphorylation

formation of ATP w/out involvement of electron transport chain. after glycolysis, if oxygen available, pyruvate moves through mitochondrial membranes by active transport

name the site of glycolysis

cytoplasm

reactants of glycolysis

• 1 glucose molecule

• 2 ATP molecules

products of glycolysis

• 4 ATP molecules

• 2 reduced NAD molecules

• 2 pyruvate molecules

net energy gain of glycolysis

• 2 ATP molecules

• 2 reduced NAD molecules (per glucose molecule)

roles of glycolysis products

pyruvate + reduced NAD contribute to later stages of cellular respiration for greater energy yield