4.4 Respiration

Question 1

Describe the steps in Glycolysis.

Answer 1

1- Hydrolysis of 2 ATPs form 2 ADPs and 2 Pi which attach together, activations the glucose.
2- Each phosphorylase do glucose splits into 2 TP (3 Carbon)
3- H is removed from each TP and is transferred to the electron carrier NAD forming NADH
4- Enzyme controlled reactions convert each TP into pyruvate (3 carbon). In the process 2 ATP are regenerated from ADP

Question 2

Describe the Links Reaction.

Answer 2

1- Pyruvate is actively transported into the matrix of the mitochondria
2- Pyruvate is oxidised (loses H), which is accepted by NAD, forming NADH, and forms Acetyl group (2 carbons) and a CO2 from each pyruvate
3- Acetyl group combines with coenzyme A (CoA) forming Acetylcoenzyme A

Question 3

Describe the Krebs Cycle.

Answer 3

1- Acetyl Coenzyme A combines with a 4 carbon molecule, forming a 6 carbon molecule which enters the Krebs cycle.
2- A series of oxidation-reeducation reactions take place, forming reduced coenzymes (NADH and FADH), carbon dioxide, ATP and reforming the 4 carbon molecule by substrate level phosphorylation

Question 4

Where does glycolysis occur?

Answer 4

In the cytoplasm of living cells

Question 5

Describe the steps in the Electron Transport Chain

Answer 5

• Reduced FAD and NAD donate electrons in the first molecule in the ETC
• The released protons from the H are actively transported across the mitochondrial membrane
• Electrons pass along ETC by oxidation-reduction reactions, losing energy at each stage, used to from ATP from ADP and Pi
• Protons build up between 2 mitochondrial membranes, before diffusing back into the mitochondrial matrix via channel proteins, the energy produced from this form ATP from ADP and Pi
• At the end of the ETC the elections combine with oxygen forming water. Oxygen is the final electron acceptor.

Question 6

Describe the two types of anaerobic respiration

Answer 6

• In plants and microorganisms pyruvate is converted into ethanol and carbon dioxide
• In animals the pyruvate is converted into lactase

Question 7

Describe the production of Ethanol in plants

Answer 7

The pyruvate molecule formed in glycolysis loses a molecule of carbon dioxide, an accepts hydrogen from the reduced NAD, producing ethanol.

Question 8

Equation for the production of ethanol in plants

Answer 8

Pyruvate + NADH —> ethanol + carbon dioxide + NAD

Question 9

Describe the production of lactase in animals

Answer 9

• Commonly occurs in muscles due to strenuous exercise
• In his situation oxygen is used faster than it is supplied, creating an oxygen debt
• Usually glycolysis would stop as the NAD accumulates
• To prevent this the pyruvate takes up 2 hydrogens from NADH forming lactase

Question 10

The equation for the production of lactase in animals

Answer 10

Pyruvate + NADH —> lactase + NAD