introduction to glycolysis

• glycolysis: 1st stage of aerobic respiration, occurs in cytoplasm of cells

• breaks glucose, a 6-carbon molecule, into 2 3-carbon pyruvate molecules. this happens through series of reactions involving specific enzymes

• glycolysis doesn’t require oxygen = anaerobic process. as well as pyruvate, glycolysis also produces small amounts of ATP + electron carrier “reduced NAD (NADH)”

main steps of glycolysis

process of glycolysis divided into four stages:

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

glycolysis: reactants and products

Reactants:

• 1 glucose molecule

• 2 ATP molecules

Products:

• 4 ATP molecules

• 2 reduced NAD molecules

• 2 pyruvate molecules

Net Energy Gain:

• 2 ATP molecules

• 2 reduced NAD molecules (per glucose molecule)

Roles of Products:

• Pyruvate + reduced NAD contribute to later stages of cellular respiration for greater energy yield.