Enzymes and their kinetics
How enzymes speed up reactions: active site, activation energy, maximum velocity and Km, competitive and non-competitive inhibitors, cofactors, and the use of enzymes in medicine, as drug targets and as blood markers.
- 34 cards
- 3 topics
- Free
The outline, topic by topic
Each topic is weighted the way the exam weighs it.
- Concepts
- Scenarios
- Understand
A few cards from the deck
Enzyme: what is it?
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A protein that speeds up a chemical reaction without being used up.
It does not change the reaction's equilibrium, only how fast it is reached.
In methanol poisoning, fomepizole (or ethanol) is given. Why?
- It occupies alcohol dehydrogenase and stops the methanol's toxic products from forming
- It binds methanol in blood and neutralises it
- It speeds up the conversion of methanol to formic acid
- It makes urine alkaline to speed methanol elimination
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It occupies alcohol dehydrogenase and stops the methanol's toxic products from forming
It is competitive inhibition: methanol is removed intact, by the kidney or dialysis.
Active site: what is it?
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The region of the enzyme where the substrate binds and the reaction happens.
Its shape explains the enzyme's specificity.
Does an enzyme change the final outcome of a reaction?
- Yes, it makes more product
- Yes, it reverses the reaction
- The reaction uses it up
- No, it reaches the same equilibrium faster
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No, it reaches the same equilibrium faster
It lowers the activation energy in both directions.
Activation energy: what is it?
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The energy needed to get a reaction started.
The enzyme lowers it, making the reaction possible at body temperature.
Transaminases (ALT) are ten times normal. Which organ is affected?
- The heart
- The liver
- The thyroid
- The kidney
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The liver
ALT is mainly hepatic: its release signals liver cell damage.