kms Flashcards
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Where does cellular respiration take place?
Cytoplasm and mitochondria
Glycolysis occurs in the cytoplasm, while the Krebs cycle and the electron transport chain (ETC) occur in the mitochondria.
Where does the process of fermentation take place?
Cytoplasm
Fermentation occurs entirely in the cytoplasm.
What are the 2 metabolic pathways a cell can use and what does it depend on?
Aerobic respiration and fermentation.
The pathway depends on the availability of oxygen.
Sequence of steps of the Fermentation Pathway:
- Glycolysis. 2. Conversion of pyruvate to either lactic acid or ethanol and carbon dioxide.
Sequence of steps of the Cellular Respiration Pathway:
- Glycolysis. 2. Pyruvate oxidation. 3. Krebs cycle (citric acid cycle). 4. Electron transport chain (ETC) and oxidative phosphorylation.
How many molecules of ATP are released during glycolysis?
4 ATP produced, but 2 ATP are consumed, yielding a net gain of 2 ATP.
How many molecules of ATP are produced after the entire Fermentation pathway?
2 ATP per glucose.
How many molecules of ATP are produced after the entire Cellular Respiration pathway (from 1 molecule of glucose)?
36–38 ATP.
How many molecules of ATP are produced from the Krebs cycle for 1 molecule of pyruvic acid?
1 ATP (or GTP) per pyruvate, so 2 ATP per glucose.
Lactic Acid Fermentation equation:
Glucose → 2 Lactic acid + 2 ATP.
Alcoholic Fermentation equation:
Glucose → 2 Ethanol + 2 CO₂ + 2 ATP.
Cellular Respiration equation:
C₆H₁₂O₆ + 6 O₂ → 6 CO₂ + 6 H₂O + 36–38 ATP.
Main reactant and products of Cellular Respiration:
Reactant: Glucose (C₆H₁₂O₆) and oxygen (O₂). Products: Carbon dioxide (CO₂), water (H₂O), and ATP.
Molecules involved in glycolysis:
Start: Glucose. End: 2 Pyruvate, 2 NADH, and 2 ATP (net).
ATP molecules in glycolysis:
2 ATP required to start. 4 ATP produced, resulting in a net gain of 2 ATP.
Reactants and products of glycolysis:
Reactants: Glucose, 2 NAD⁺, 2 ADP, 2 Pi. Products: 2 Pyruvate, 2 NADH, 2 ATP (net), 2 H₂O.
What are NAD⁺ and FAD?
NAD⁺ and FAD are electron carriers.
They accept electrons to become NADH and FADH₂, which transport electrons to the ETC.
Why does fermentation occur after glycolysis?
To regenerate NAD⁺ so glycolysis can continue in the absence of oxygen.
Types of fermentation and examples:
Lactic Acid Fermentation: Occurs in muscles during intense exercise, producing lactic acid. Alcoholic Fermentation: Occurs in yeast, producing ethanol and CO₂.
Reactants and products of lactic acid fermentation:
Reactants: Pyruvate, NADH. Products: Lactic acid, NAD⁺.
Reactants and products of alcoholic fermentation:
Reactants: Pyruvate, NADH. Products: Ethanol, CO₂, NAD⁺.
Starting molecule entering the Krebs cycle:
Acetyl-CoA.
Products of the Krebs Cycle per pyruvate:
3 NADH, 1 FADH₂, 1 ATP (or GTP), 2 CO₂.
Products of the Krebs Cycle per glucose:
6 NADH, 2 FADH₂, 2 ATP (or GTP), 4 CO₂.
Main purpose of the Krebs cycle:
To generate high-energy electron carriers (NADH, FADH₂) for the ETC.
Where do NADH and FADH₂ go after the Krebs cycle?
To the electron transport chain in the inner mitochondrial membrane.
What happens to the electrons in the electron carriers?
They are transferred through the ETC, driving proton pumps and creating a proton gradient.
ATP from each electron pair:
NADH: ~2.5 ATP. FADH₂: ~1.5 ATP.
Energy from the ETC is used to:
Pump protons across the inner mitochondrial membrane, creating a gradient for ATP synthesis.
Role of ATP synthase:
ATP synthase uses the proton gradient to convert ADP + Pi into ATP during oxidative phosphorylation.
Correct sequence of cellular respiration:
- Glycolysis. 2. Pyruvate oxidation. 3. Krebs cycle. 4. Electron transport chain and oxidative phosphorylation.
Energy sources during a workout:
- First few seconds: Stored ATP. 2. 10–30 seconds: Creatine phosphate. 3. Minutes: Glycolysis and lactic acid fermentation. 4. Prolonged exercise: Aerobic respiration (carbohydrates, fats).
