L. 11 (aerobic) cellular respiration (of eukaryotes)

Question 1

LO

Answer 1

• Describe, in overview, the Krebs (TCA) cycle and glycolysis
• Describe the electron transport chain and oxidative phosphorylation in mitochondria
• Compare photosynthetic electron transport and the electron transport
  chain in mitochondria

Question 2

Redox in photosynthesis Vs Respiration

Answer 2

Photosynthesis:
- C from CO2 is reduced to form glucose

Respiration:
- C from glucose is oxidized to become CO2

Question 3

Structure of Mitochondria

Answer 3

[heft]

• Outer membrane
• Intermembrane space
• Inner membrane (ETC)
• Cristae
• Matrix (krebs cycle)

Question 4

Cellular respiration steps

Answer 4

Glycolysis
Krebs cycle
ETC
ATP Synthesis

Question 5

Glycolysis

Answer 5

1. Glucose uses 2x ATP to form 2x 6C molecules (glucose bisphosphate)
2. 6C splits into 2x 3C
3. 2x 3C are oxidized, reducing NAD+ into NADH.
4. 4xATP is created from 4x ADP molecules converting each 3C molecule into pyruvate.

Net Products = 2xATP, 2xNADH, 2xPyruvate

Question 6

Krebs Cycle

Answer 6

1. Pyruvate undergoes the link reaction and is decarboxylated, turning into Acetyl (2C)
2. Acetyl binds to Co-enzyme A, forming Acetyl CoA.
3. Acetyl CoA binds to 4C molecule to from 6C molecule.
4. 6C is decarboxylated and oxidized, reducing NAD+ into NADH. CO2 is waste
5. 5C is decarboxylated and oxidized agian, reducing NAD+ and ADP. CO2 is waste
6. 4C molecule is oxidized again, reducing FAD into FADH2 and NAD+ into NADH+
7. 4C is recycled.
8. Cycle must repeat twice per molecule of glucose

Question 7

Electron transport chain

Answer 7

• Reduced electron carriers (NADH, FADH) from the krebs cycle entre the ETC.
• High energy e- are released from NADH and FADH2 and flow down 4 protein complexes.
• As the e- pass the protein complexes, H+ ion are pumped from the matrix into the intermembrane space.
• A high H+ concentration builds in the intermembrane space.
• H+ ions then diffuse down concentration gradient through ATP synthase
• Movement of H+ ions through ATP synthase gives energy to synthesise ATP.
• e- on last protein complex has low energy and is picked up by an oxygen, which binds oxygenb with 2xH to form H2O.

Question 8

Respiration Vs. Photosynthetic ETC and Plant thermogenesis

Typical Exam Q.

Answer 8

[heft]
- Both ETC invoolved in energy conversion.

Respiration ETC:
- Mitochondria
- Converts energy from NADH & FADH2 into ATP
- NADH, FADH2 are e- donors
- final electron acceptor is oxygen
- Protons pumped from matrix into intermembrane space

Photosynthetic ETC:
- Chloroplast
- Light energy into chemical
- H2O is e- donor
- final electron acceptor is NADP+, which is reduced
- protons pumped from the stroma into the thylakoid lumen