C1.2 Cellular Respiration

Question 1

What is ATP?

Answer 1

Adenosine triphosphate is a nucleotide that distributes energy within cells.

Question 2

Properties of ATP

Answer 2

• Soluble in water –> can move freely through the cytoplasm.
• Stable at pH levels close to neutral.
• Cannot freely pass through the phospholipid layer of membranes –> movement within cells is controlled.
• Third phosphate group can be easily removed and reattached through condensation and hydrolysis.

Question 3

What are the life processes within cells that ATP supplies with energy?

Answer 3

1. Active transport across membranes
2. Synthesizing macromolecules
3. Movement of whole cell or cell components

Question 4

Energy transfers during interconversions between ADP and ATP

Answer 4

• Energy is released by hydrolysis of ATP to ADP and phosphate.
• Energy is required to synthesize ATP from ADP and phosphate.
• Energy from ATP is used in cells and converted to heat –> eventually lost in environment hence, cells require continuous source of ATP for activities.

Question 5

Distinguish between AEROBIC and ANAEROBIC RESPIRATION.

Answer 5

• Aerobic uses oxygen, anaerobic doesn’t.
• Aerobic uses carbohydrates and lipids, anaerobic only uses carbohydrates.
• Aerobic has a higher ATP yield than anaerobic per glucose molecule.
• Aerobic by-products are CO2 and water, but for anaerobic it is ethanol in yeast and lactate in humans.

Question 6

Define cellular respiration

Answer 6

The controlled release of energy from organic compounds in cells to form ATP.

Question 7

Explain how ATP is generated in animal cells.

Answer 7

1. ATP is generated through cell respiration.
2. Cell respiration is the controlled release of energy from organic compounds in cells to form ATP.
3. There is aerobic and anaerobic respiration.
4. Aerobic respiration requires oxygen, anaerobic respiration does not.
5. Glycolysis - breaks down glucose into pyruvate; happens in the cytoplasm –> releases a small amount of ATP.
6. Aerobic respiration happens in the mitochondria –> large yield of ATP.
7. When ADP is synthesized into ATP –> becomes a form of energy that is available to all.

Question 8

How does ATP work?

Answer 8

1. Phosphorylation - kinase enzyme transfers phosphate group from ATP to a substrate.
2. The phosphorylated substrate becomes activated and when it loses its Pi, the energy released can be used to do cellular work.
3. Cellular respiration - the Pi can be recycled and added to an ADP to create a new ATP.