Biological Reactions Regulated By Enzymes- Unit 1.4 Flashcards
Where do the enzyme and substrate combine?
The active site
What protein structure do all enzymes have?
Tertiary in 3D spherical globular shape
Anabolic vs catabolic enzymes.
Anabolic- build larger products from smaller substrates.
Catabolic- break large substrates into smaller products.
What is the function of a lysozyme?
To destroy pathogenic bacteria by breaking down their cell walls by breaking glycosidic bonds between the amino sugars.
How is a substrate held in place when attached to a lysozyme?
Hydrogen and ionic bonds
What is the lock and key hypothesis?
There is an exact fit between substrate and active site of an enzyme.
What is the induced fit hypothesis?
Active site is not exactly the right shape to begin with. The substrate changes the shape of the active site to fit the substrate perfectly. (complementary shape)
Name 2 enzyme properties.
- Specific- each enzyme will catalyse only one particular reaction.
- Very efficient & have a high turnover number. (can convert many molecules of substrate into product per unit)
What is activation energy and what is it used for?
Energy needed to start chemical reactions by breaking chemical bonds inside molecules.
Do body enzymes increase or decrease the activation energy of a reaction?
The lower it, reducing input of energy needed to allow reactions to take place, meaning they can take place at lower temperatures.
What are the factors that can affect enzyme activity? (4)
Changing:
- Temperature
- pH
- Substrate concentration
- Enzyme concentration
What happens when temperature is increased?
- Gives molecules greater kinetic energy as enzyme & substrates move around quicker, increasing chance of collision.
- Increase rate of reaction.
For each 10°C rise…
Rate of reaction doubles
general rule
How do enzymes denature?
Vibrations break hydrogen bonds within the active site, causing shape to change.
What is the turn-over number?
The number of substrate molecules that one enzyme molecule can turn into products in a given time.
What is a limiting factor?
A factor is limiting when an increase in its value causes an increase in rate of reaction.
What is an enzyme inhibitor? (2)
- Any substance which decreases rate of an enzyme catalysed reaction or stops it.
- Can be competitive of non-competitive.
Describe competitive inhibitors. (2)
- Structurally similar to substrate.
* Can fit into active site, preventing enzyme-substrate complex forming.
What effect will increasing substrate concentration have on a competitive inhibitor?
Decreasing likeliness of inhibitor colliding with enzyme as less likely to bind with active site.
Describe non-competitive inhibitors. (2)
- Do not bind to active site, but does anywhere else.
* Alters overall shape or enzyme, including active site so that substrates cannot fit onto it.
What effect will increasing substrate concentration have on a non-competitive inhibitor?
Will not increase rate of reaction as substrate can no longer fit into enzymes active site.
What are immobilised enzymes?
Fixed, bound or trapped on an inert matrix. (prevent them from moving, reducing frequency of successful collisions)
Name advantages of using immobilised enzymes. (7)
- Enzyme does not contaminate product.
- Can be recovered & reused.
- Only small quantity needed.
- Great stability.
- Denature at higher temperatures.
- Catalyse reactions over wider range of pH.
- Greater control over process.
What are biosensors?
Can detect biologically important molecules rapidly, even at low concentrations.
e.g. Used to measure blood glucose in diabetics.
How do biosensors work?
Use immobilised enzymes on a gel membrane to detect chemical changes and turns it into an electrical signal.
