C1.1 Enzymes and metabolismIB Biology HL: Flashcards
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Anabolism vs catabolism?
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- Anabolism vs catabolism?
- Anabolism builds macromolecules by condensation; catabolism breaks them down by hydrolysis or oxidation.
- What is induced fit?
- Both enzyme and substrate change shape when the substrate binds.
- Why does rate plateau at high substrate concentration?
- All active sites are occupied (saturation).
- What do enzymes do to activation energy?
- Lower it, without changing the overall energy released.
- HL: Intracellular vs extracellular enzyme examples?
- Intracellular: glycolysis, Krebs cycle. Extracellular: chemical digestion in the gut.
- HL: Why does metabolism generate heat?
- Energy transfers in metabolic reactions are not 100% efficient; mammals and birds use the heat to keep body temperature constant.
- HL: Linear vs cyclical pathways?
- Linear: glycolysis. Cyclical (starting molecule regenerated): Krebs cycle, Calvin cycle.
- HL: What happens when a molecule binds to an allosteric site?
- A reversible conformational change alters the active site and prevents catalysis.
- HL: How does a competitive inhibitor work? Example?
- It resembles the substrate and binds reversibly to the active site; statins.
- HL: Effect of high substrate concentration on competitive vs non-competitive inhibition?
- Competitive is overcome; non-competitive is not.
- HL: Feedback inhibition example?
- Isoleucine inhibits threonine deaminase, the first enzyme in its own synthesis pathway.
- HL: What is mechanism-based inhibition? Example?
- Irreversible binding that chemically changes the active site; penicillin and transpeptidase.
- HL: How are bacteria resistant to penicillin (in this topic)?
- They make a modified transpeptidase to which penicillin does not bind.