Metabolism: Capturing and Spending Energy
Key ideas about ATP, photosynthesis, and cellular respiration from the lesson.
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Questions Covered in This Set
11 cards to master
What is metabolism?
The whole bookkeeping operation of a cell: capturing, storing, transferring, and spending chemical energy.
Why doesn't life violate the Second Law of Thermodynamics?
Organisms maintain internal order by importing high-quality energy and exporting heat and disorder to their surroundings.
What is ATP and how much energy does its hydrolysis release?
Adenosine triphosphate, the cell's universal energy currency; hydrolysis to ADP + phosphate releases roughly 30 kJ/mol.
What does 'coupling' mean in metabolism?
An enzyme holds ATP and a target molecule together so phosphate transfer makes an unfavourable (positive ΔG) reaction part of a net negative-ΔG reaction.
Is ATP a long-term energy store?
No — a cell holds only ~1 gram at a time; it's a fast-recycled cash float. Long-term storage uses glycogen, fat, and geologically wood/coal/oil.
What happens in the light reactions of photosynthesis?
In thylakoid membranes, photons excite chlorophyll electrons; water is split (releasing O₂), protons are pumped, and ATP synthase plus NADPH production follows.
What does the Calvin cycle do?
In the stroma, it spends ATP and NADPH to attach CO₂ to a 5-carbon sugar via RuBisCO, building glucose from six fixed carbons.
Why is RuBisCO notable?
It's probably the most abundant protein on Earth, yet is notoriously slow and sometimes grabs O₂ by mistake.
What does glycolysis produce, and where?
In the cytoplasm it splits glucose into two pyruvates, netting only 2 ATP; it's ancient, oxygen-free, and your sprint emergency system.
What is the real job of the citric acid (Krebs) cycle?
Not making much ATP, but peeling electrons off carbon and loading them onto NADH and FADH₂.
How does the electron transport chain make ATP?
Electrons tumble toward oxygen (the final acceptor, becoming water), releasing energy to pump protons; protons rush back through ATP synthase.
