Question

Ch. 9 11) What are the four steps of cellular respiration? What are the initial reactants and final products from each of these steps (include NADH and FADH2)? Where do they occur in the cell/mitochondria? 12) Why is the pyruvate processing step necessary? Why not go straight to the citric acid cycle? 13) What is homeostasis? How does cellular respiration play a role in anabolic reactions (think intermediates)? 14) How are the first three steps of cellular respiration regulated? 15) What is the purpose of making NADH and FADH2? Are they reduced or oxidized? 16) What is the difference between oxidative Phosphorylation and substrate Phosphorylation? Which steps of cellular respiration does substrate Phosphorylation occur? 17) Compare and contrast aerobic respiration, anaerobic respiration, and fermentation? Why is aerobic respiration the most efficient? 18) What is the purpose of fermentation? How many ATP's are made? 19) Briefly describe what happens to the electrons and protons in the electron transport chain? 20) How is proton motive force connected to ATP synthesis electron transport and chemiosmosis? 21) What other sources of carbons, aside from glucose, can be used in cellular respiration? 22) What does it mean to say that glucose is oxidized? What molecule is broken down/oxidized to?

Answer 1

11) Cellular respiration

The biochemical pathway by which energy is converted into ATP by utilizing nutrients is called cellular respiration. The four steps of cellular respiration are as follows:

1. Glycolysis

2. Pyruvate oxidation

3. Kreb's cycle

4. Electron transport chain (ETC)

1. Glycolysis

The initial product, glucose is converted into the final product, pyruvate where ATP is produced and NAD⁺ is converted into NADH.

2. Pyruvate oxidation

Pyruvate is converted into acetyl CoA along with the generation of NADH and the release of CO₂.

3. Kreb's cycle

Acetyl CoA undergoes a series of reactions with the aid of different enzymes at each step and finally produces ATP, NADH and FADH₂, along with the release of CO₂.

4. ETC

The electrons of NADH and FADH₂ go in this cycle and release energy along with the pumping of protons which results in the formation of electrochemical gradient. ATP is produced with the help of ATP synthase.

Glycolysis occurs in the cytosol in both prokaryotes and eukaryotes; Pyruvate oxidation occurs in the cytosol for prokaryotes and mitochondrial matrix for eukaryotes; Kreb's cycle occurs in the cytosol for prokaryotes and mitochondrial matrix for eukaryotes; and ETC occurs in the plasma membrane for prokaryotes and inner mitochondrial membrane for eukaryotes.