Glycolysis

The first stage of respiration

Glycolysis

Respiration

• Process of respiration is split into four parts

• By breaking it into four parts we will have less to learn at any one stage

Glycolysis is the first stage of respiration!

Glycolysis is the first stage of respiration!

Glycolysis splits one molecule of glucose into two smaller molecules of pyruvate

Glycolysis is the first stage of respiration!

Glycolysis splits one molecule of glucose into two smaller molecules of pyruvate

Glucose is a hexose (6-carbon) molecule

Glycolysis is the first stage of respiration!

Glycolysis splits one molecule of glucose into two smaller molecules of pyruvate

Glucose is a hexose (6-carbon) molecule

Pyruvate is a triose (3-carbon) molecule

Glycolysis is the first stage of respiration!

Glycolysis splits one molecule of glucose into two smaller molecules of pyruvate

Glucose is a hexose (6-carbon) molecule

Pyruvate is a triose (3-carbon) molecule

Pyruvate is also known as pyruvic acid

• Glycolysis takes place in the cytoplasm of cells.

• Glycolysis takes place in the cytoplasm of cells.

• It’s the first stage of both aerobic and anaerobic respiration.

• It’s the first stage of both aerobic and anaerobic respiration.

•It doesn’t need oxygen to take place – so it’s anaerobic

• It’s the first stage of both aerobic and anaerobic respiration.

•It doesn’t need oxygen to take place – so it’s anaerobic

There are TWO STAGES of GLYCOLYSIS – Phosphorylation and Oxidation

Glycolysis

Glycolysis

1

2

A

B

Glycolysis

1

2

A

B

These arrows in diagrams just mean that A goes into the main reaction and is

converted to B.

A will normally release or collect something from

molecule 1, e.g. hydrogen or phosphate

Stage One - Phosphorylation

Stage One - Phosphorylation

1.Glucose is phosphorylated by adding 2 phosphates from 2 molecules of ATP to give a hexose phosphate.

Stage One - Phosphorylation

1.Glucose is phosphorylated by adding 2 phosphates from 2 molecules of ATP to give a hexose phosphate.

2.The hexose phosphate is split using water

Stage One - Phosphorylation

1.Glucose is phosphorylated by adding 2 phosphates from 2 molecules of ATP to give a hexose phosphate.

2.The hexose phosphate is split using water (hydrolysis)

Stage One - Phosphorylation

1.Glucose is phosphorylated by adding 2 phosphates from 2 molecules of ATP to give a glucose phosphate.

2.The glucose phosphate is split

3.2 molecules of triose phosphate and 2 molecules of ADP are created.

What’s the point?

• Glucose can now no longer leave the cell.

What’s the point?

• Glucose can now no longer leave the cell.

• Molecules produced are much more reactive!

Stage Two - Oxidation

Stage Two - Oxidation

1.The triose phosphates are oxidised (lose oxygen), forming two molecules of pyruvate.

Stage Two - Oxidation

1.The triose phosphates are oxidised (lose oxygen), forming two molecules of pyruvate.

2. Coenzyme NAD+ collects the hydrogen ions, forming 2 reduced NAD (NADH + H+)

Stage Two - Oxidation

1. The triose phosphates are oxidised (lose oxygen), forming two molecules of pyruvate.

2. Coenzyme NAD+ collects the hydrogen ions, forming 2 reduced NAD (NADH + H+)

A coenzyme is a helper molecule that carries chemical groups or ions, e.g. NAD+ removes H+ and carries it

to other molecules.

Stage Two - Oxidation

1.The triose phosphates are oxidised (lose oxygen), forming two molecules of pyruvate.

2. Coenzyme NAD+ collects the hydrogen ions, forming 2 reduced NAD (NADH + H+)

3. 4 ATP are produced, but 2 were used up at the beginning, so there’s a net gain of 2 ATP.

Next in Aerobic respiration….

Next in Aerobic respiration….

1. The 2 molecules of reduced NAD go to the electron transport chain (ETC), part 4 of respiration.

Next in Aerobic respiration….

1. The 2 molecules of reduced NAD go to the electron transport chain (ETC), part 4 of respiration.

2. The two pyruvate molecules go into the matrix of the mitochondria for the link reaction.