Lecture 5 Flashcards
What is the first law of thermodynamics?
The law of conservation of energy; energy cannot be created or destroyed, only transferred or transformed.
What are the two ways ATP can be generated?
1) Substrate-level phosphorylation (direct ATP production from food molecules).
2) Oxidative phosphorylation (ATP production using an electron transport chain in mitochondria).
What are the three stages of food breakdown?
- Stage 1: Food broken into simple subunits (outside the cell).
- Stage 2: Subunits converted to Acetyl CoA (mostly in cytosol), producing limited ATP and NADH.
- Stage 3: Acetyl CoA enters mitochondria, producing ATP via oxidative phosphorylation.
What is the role of NADH and FADH₂ in oxidative phosphorylation?
They act as electron carriers that donate high-energy electrons to the electron transport chain (ETC).
Where does oxidative phosphorylation take place?
The inner mitochondrial membrane.
How is ATP generated through oxidative phosphorylation? (3 steps)
- High-energy electrons from NADH & FADH₂ pass through the electron transport chain (ETC).
- This powers proton pumps that create a proton gradient across the inner mitochondrial membrane.
- Protons flow back through ATP synthase, which converts ADP + Pi into ATP.
What is the final electron acceptor in oxidative phosphorylation?
Oxygen (O₂), forming water.
How many ATP molecules does one turn of ATP synthase produce?
3 ATP per full rotation.
What are the key compartments of the mitochondrion? (4)
Outer membrane (permeable to small molecules).
Inner membrane (houses ETC, ATP synthase).
Intermembrane space (proton gradient forms here).
Matrix (contains enzymes for citric acid cycle).
What is the evidence that mitochondria evolved from bacteria? (3)
- Own DNA (circular like bacteria).
- Double membrane (suggesting engulfment by ancestral cells).
- Reproduce via binary fission.
What are the two stages of photosynthesis?
- Light-dependent reactions (Stage 1) – Chlorophyll absorbs light, generating ATP and NADPH.
- Carbon fixation (Calvin Cycle) (Stage 2) – ATP & NADPH convert CO₂ into sugars.
Where does the light-dependent reaction occur?
Thylakoid membrane in chloroplasts.
Where does the Calvin Cycle take place?
Stroma of the chloroplast.
What molecule captures light energy in photosynthesis?
Chlorophyll (found in the thylakoid membrane).
What are Photosystem I and Photosystem II responsible for?
Photosystem II (PSII): Generates ATP and splits water molecules, producing O₂.
Photosystem I (PSI): Produces NADPH for the Calvin Cycle.
What is the source of oxygen produced during photosynthesis?
Splitting of water (H₂O) in Photosystem II.
What is the overall equation for photosynthesis?
Light + CO₂ + H₂O → Sugars + O₂ + Heat energy
What are the similarities between oxidative phosphorylation and photosynthesis? (3)
- Both involve an electron transport chain (ETC).
- Both generate ATP using ATP synthase.
- Both create a proton gradient across a membrane.
What is the main difference between mitochondria and chloroplasts? (3)
- Mitochondria generate ATP from food (oxidative phosphorylation).
- Chloroplasts generate ATP from light energy (photosynthesis).
- Chloroplasts have a third membrane (thylakoid membrane), which is absent in mitochondria.
What is ATP synthase?
Converts proton-motive force into ATP.
What is the electron transport chain (ETC)?
Series of proteins that transfer electrons, creating a proton gradient.
What is chemiosmosis?
Process where proton movement drives ATP synthesis.
What is rubisco?
Enzyme that catalyzes carbon fixation in the Calvin Cycle.
what is endosymbiont theory?
Theory that mitochondria & chloroplasts originated from engulfed bacteria.
