Enzymes Flashcards
1
Q
Give examples of processes enzymes are used for.
A
- Digestion
- DNA and RNA synthesis
- Energy production
2
Q
What are the characteristics of enzymes?
A
- Proteins
- Biological Catalysts
- Lower activation energy
- Not altered or consumed during reaction
3
Q
What are the two functional groups within the active site?
A
- BINDING SITE - where substrate binds
- CATALYTIC SITE - where reaction catalysed
4
Q
Describe the enzyme-substrate complex.
A
- Transiton state at high energy state
- Intermediate between substrate and product
- Reaction occurs by making/breaking bonds to form product
5
Q
What are three types of specificity and what contributes to enzyme specificity?
A
- ABSOLUTE - Catalyse one reaction type for single substrate
- GROUP - Similar to absolute - for similar substrates
- LINKAGE - Similar to absolute - for specific bond type
- Tertiary structure contributes to specificity
6
Q
Do enzymes alter ΔG?
A
No
7
Q
Describe the lock-and-key model
A
- Active site has a rigid shape
- Only substrates with matching shape fit active site
8
Q
Describe the induced fit model.
A
- Active site is flexible
- Shapes of enzyme, active site and substrate adjust to maximise fit, improving catalysis
9
Q
Why is the optimum temperature for most enzymes 37 degrees?
A
- Temperature at which enzymatic reaction occurs fastest
10
Q
What occurs when pH increases to physiological pH?
A
- Ionisation of functional groups
- Optimum pH is usually 7
- Varies depending on level of acidity of environment
11
Q
When does Vmax occur?
A
Vmax - maximal activity
- Occurs when enzyme is saturated - all enzymes have bound substrate
12
Q
What is the difference between an apoenzyme and holoenzyme?
A
- APOENZYME - Inactive enzyme without its cofactor
- HOLOENZYME - Active enzyme with its cofactor
13
Q
What are cofactors?
A
- Inorganic/organic non-protein components
- Bound covalently or loosely to enzyme
14
Q
What are coenzymes?
A
- Organic non-protein components
- Loosely bound to apoenzyme by non-covalent bonds
- EXAMPLE: NAD and FAD
15
Q
What are prosthetic groups?
A
- Permanent part of tertiary structure
- Tightly bound to apoenzyme by covalent bonds
- EXAMPLE: Haem group in Hb
