In cellular Respiration, I don't understand the Krebs Cycle, and The Electron Transport Chain. Please Explain.

Question

I dont understand how both processes work

Answer 1

The complete biochemical pathways of cellular respiration is rather complex, and when written would fill a large wall chart. I don't know to what extent you're expected to know. If you are a high school student, don't be intimidated, this is not one of the most popular topics in bio. class! Basically, there are two main events; an anaerobic phase (no free oxygen needed)and an aerobic phase. The Kreb's
cycle & ETC are part of the aerobic phase and produce most of the ATP per glucose molecule. Here's what I suggest: Carefully read & reread the topic in your textbook with a pencil in hand. Summarize each
reaction in an outline form. If your textbook is not clear, go to the library and get one or two more textbooks that look easier.

Answer 2

they're really easy actually.

a. Krebs Cycle
1. Turns twice for each molecule of glucose oxidised
2. mainly the oxidation of acetyl CoA in a series of enzymatically driven reactions
3. Only occurs in aerobic conditions.
4. Occurs in the matrix of the mitochondria
5. ATP is formed via substrate level phosphorylation
- SLP is enzyme-mediated
- involves the transer of a high energy free phosphate group from a phosphorylated chemical molecule to ADP in an exergonic catabolic pathway
6. Every time there is a reduction in number of carbons, carbon dioxide is produced
- citrate (6C) to alpha-ketoglutarate (5C)
- alpha-ketoglutarate (5C) to succinate (4C)
7. Input per turn:
- 1 acetyl CoA
- 1 ADP + Pi (phosphate group)
- 3 NAD+
- 1 FAD
8. Ouput per turn:
- 2 CO2
- 1 ATP
- 3 (NADH + H+)
- 1 FADH2

b. Electron Transport Chain (ETC)
1. each NADH + H+ & FADH2 contains a pair of electrons
2. electrons are passed to a series of hyrogen & electron carriers found in the inner mitochondrial membrane
3. electrons are passed down from one carrier to the next down progressively lower energy levels
4. oxygen is the final electron acceptor and is reduced to water
5. energy released at each transfer is used for ATP formation
6. ATP is formed via oxidative phosphorylation
- each electron carrier undergoes a redox reaction
- chemiosmosis is the mechanism in OP
- energy released from electron transport is used to pump hydrogen ions from mitochondrial matrix across inner mitochondrial membrane to intermembrane space
- this results in the accumultion of hydrogen ions in the intermembrane space
- pH gradient & electrical potential created across the inner mitochondrial membrane (electrochemical proton gradient)
- inner mitochondrial membrane is impermeable to hydrogen ions
- hydrogen ions diffuse across membrane down concentration gradient via ATP synthetase
- energy released is used to synthesise ATP
7. NADH + H+ gives rise to 3 ATP
8. FADH2 gives rise to 2 ATP

So, for 1 molecule of glucose oxidised in tissue respiration, you get 2 ATP from the Krebs Cycle and 34 ATP from the ETC.