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Enzymes Structure Function and Regulation
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Enzymes Structure Function and Regulation
Enzymes Structure Function and Regulation
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1
Question
What are enzymes and what is their primary role in cells?
Answer
Enzymes are catalysts that speed up biochemical reactions in cells.
2
Question
What is activation energy and how do enzymes affect it?
Answer
Activation energy is the energy barrier for a reaction; enzymes lower it.
3
Question
Are enzymes consumed in the reaction they catalyze?
Answer
No, they are not consumed.
4
Question
What is an apoenzyme?
Answer
The protein part of a conjugated enzyme.
5
Question
What is a holoenzyme?
Answer
The biochemically active conjugated enzyme (apoenzyme + cofactor).
6
Question
What is a cofactor in enzyme chemistry?
Answer
A nonprotein component aiding catalysis.
7
Question
What is the function of metal ions in enzymes?
Answer
Serve as essential inorganic cofactors (e.g., Zn2+, Mg2+).
8
Question
What distinguishes the suffix -ase in enzyme nomenclature?
Answer
Indicates a substance is an enzyme.
9
Question
What does the prefix in an enzyme name indicate?
Answer
The type of reaction the enzyme catalyzes.
10
Question
What is the Lock and Key model's main assumption about the active site?
Answer
Active site has a fixed shape that fits only certain substrates.
11
Question
What additional flexibility does the Induced Fit model propose?
Answer
Active site adapts its shape to accommodate the substrate.
12
Question
Define enzyme specificity.
Answer
The extent to which an enzyme acts on specific substrates.
13
Question
What is absolute specificity?
Answer
Enzyme catalyzes only one reaction.
14
Question
What is linkage specificity?
Answer
Enzyme acts on a specific chemical bond.
15
Question
What is stereochemical specificity?
Answer
Enzyme acts on a specific stereoisomer.
16
Question
What type of reaction do oxidoreductases catalyze?
Answer
Oxidation-reduction (redox) reactions.
17
Question
What is the role of cofactors in oxidoreductases as shown in the lactate dehydrogenase example?
Answer
Coenzymes like NAD+ participate in redox.
18
Question
What does the transferase class accomplish?
Answer
Transfers functional groups between molecules.
19
Question
What reaction is shown by kinases?
Answer
Transfer of a phosphate group (phosphorylation).
20
Question
Give an example of a hydrolase-catalyzed reaction.
Answer
Maltose hydrolysis to glucose + glucose by maltase.
21
Question
What do lyases do, in general?
Answer
Add or remove groups to form or remove double bonds without hydrolysis or oxidation.
22
Question
What is an isomerase?
Answer
Catalyzes rearrangement of atoms to form isomers.
23
Question
What does a ligase do?
Answer
Catalyzes bond formation between substrates using ATP.
24
Question
Name a key factor that affects enzyme activity and its effect when temperature rises to optimum?
Answer
Temperature; increases collisions, raising rate until optimum is reached.
25
Question
What happens to enzymes if temperature exceeds the optimum?
Answer
Denaturation occurs.
26
Question
What is the typical optimum human body temperature for enzymes?
Answer
37°C.
27
Question
What is optimum pH and give an example for pepsin?
Answer
Optimal pH is around 7.0–7.5; pepsin is active at pH 2.0.
28
Question
How does substrate concentration affect reaction rate before saturation?
Answer
Rate increases with more substrate.
29
Question
What is saturation in enzyme kinetics?
Answer
When all active sites are occupied, rate plateaus.
30
Question
What is turnover number in enzymes?
Answer
Substrate molecules converted per enzyme per minute.