Chapter 7 Flashcards
What are autotrophs?
Organisms that can produce their own organic molecules through photosynthesis.
What are heterotrophs?
Organisms that live on organic compounds produced by other organisms.
What is cellular respiration?
A series of reactions used by organisms to extract energy from organic molecules.
What does oxidation mean in the context of cellular respiration?
Loss of electrons.
What does reduction mean in the context of cellular respiration?
Gain of electrons.
What is dehydrogenation?
The process where lost electrons are accompanied by protons, resulting in the loss of a hydrogen atom.
What role do electrons play in redox reactions?
Electrons carry energy from one molecule to another.
What is the function of NAD+?
An electron carrier that accepts 2 electrons and 1 proton to become NADH.
What is the final electron acceptor in aerobic respiration?
Oxygen (O2).
What is the final electron acceptor in anaerobic respiration?
An inorganic molecule (not O2).
What is the final electron acceptor in fermentation?
An organic molecule.
What is the overall reaction for aerobic respiration?
C6H12O6 + 6O2 → 6CO2 + 6H2O +ATP.
Krebs Cycle
What is the free energy release during aerobic respiration?
–686 kcal/mol of glucose.
What are the two mechanisms for ATP synthesis?
- Substrate-level phosphorylation
- Oxidative phosphorylation.
What is glycolysis?
A 10-step biochemical pathway that converts 1 glucose to 2 pyruvate.
Where does glycolysis occur?
In the cytoplasm.
What is produced during glycolysis?
- 2 ATP (net production)
- 2 NADH.
How is NADH recycled for glycolysis to continue?
- Aerobic respiration (using O2)
- Fermentation (when O2 is not available).
What happens to pyruvate in the presence of oxygen?
Pyruvate is oxidized to acetyl-CoA which enters the Krebs cycle.
What enzyme catalyzes the oxidation of pyruvate?
Pyruvate dehydrogenase.
What are the products of pyruvate oxidation?
- 1 CO2
- 1 NADH
- 1 acetyl-CoA.
What is the Krebs cycle?
A series of reactions that oxidizes the acetyl group from pyruvate.
What is produced for each Acetyl-CoA entering the Krebs cycle?
- 2 CO2
- 3 NADH
- 1 FADH2
- 1 ATP.
What is the total yield from glucose after the Krebs cycle?
- 6 CO2
- 4 ATP
- 10 NADH
- 2 FADH2.
What is the Electron Transport Chain (ETC)?
A series of membrane-bound electron carriers in the inner mitochondrial membrane.
What drives ATP synthesis in chemiosmosis?
The proton gradient.
What is the role of ATP synthase?
To synthesize ATP from ADP and inorganic phosphate (Pi) using the energy from the proton gradient.
What is the theoretical energy yield from glucose in bacteria?
32 ATP per glucose.
What are the two key control points in the regulation of respiration?
- Glycolysis (phosphofructokinase)
- Pyruvate oxidation/Krebs cycle (pyruvate dehydrogenase and citrate synthetase).
What is anaerobic respiration?
The use of inorganic molecules (other than O2) as the final electron acceptor.
What is fermentation?
The reduction of organic molecules to regenerate NAD+.
What happens during ethanol fermentation?
CO2, ethanol, and NAD+ are produced.
What occurs during lactic acid fermentation?
Electrons are transferred from NADH to pyruvate to produce lactic acid.
What happens to amino acids during catabolism?
They undergo deamination to remove the amino group.
What process converts amino acids to a molecule that enters glycolysis or the Krebs cycle?
Deamination
Deamination removes the amino group from amino acids.
What is alanine converted to during protein catabolism?
Pyruvate
Alanine undergoes deamination to become pyruvate.
What is aspartate converted to during protein catabolism?
Oxaloacetate
Aspartate is converted to oxaloacetate after deamination.
What are fats broken down into during catabolism?
Fatty acids and glycerol
Fats undergo hydrolysis to yield fatty acids and glycerol.
What process converts fatty acids to acetyl groups?
Beta-oxidation
Beta-oxidation is an oxygen-dependent process for fatty acid conversion.
How much more energy does the respiration of a 6-carbon fatty acid yield compared to 6-carbon glucose?
20% more energy
This indicates the higher energy yield from fat oxidation versus carbohydrate metabolism.
What is the first step in the hypothetical evolution of metabolism?
Ability to store chemical energy in ATP
ATP storage is fundamental for energy transfer in cells.
What metabolic pathway is found in all living organisms?
Glycolysis
Glycolysis is a universal pathway for glucose metabolism.
What type of photosynthesis used H2S instead of H2O?
Anoxygenic photosynthesis
Anoxygenic photosynthesis does not produce oxygen and uses H2S.
What significant change did the use of H2O in photosynthesis bring?
Permanent change in Earth’s atmosphere
The transition to using H2O led to increased oxygen levels in the atmosphere.
What evolutionary process evolved most recently?
Aerobic respiration
Aerobic respiration allows for more efficient energy production using oxygen.
