1.4 Enzymes Flashcards
Why do enzymes only catalyse one reaction?
The active site of the enzyme has a specific shape
The substrate has a complementary shape and therefore binds into the active site
How does a competitive inhibitor work?
It has a similar shape to the substrate
It had a complementary shape to the active site
It binds to the active site
When it does bind it prevents the substrate from doing so
Fewer enzyme-substrate complexes formed
Describe and explain the effect of temperature on the rate of activity of an enzyme
- increase in rate along with increase in temperature up to optimum due to increased kinetic energy so molecules move faster and more successful collisions/ more enzyme-substrate complexes formed
- at temperatures above optimum there are increased vibrations which cause the Hydrogen bonds to break and the tertiary structure changes and a change of shape of the active site and the enzyme is DENATURED
Factors affecting enzyme activity (5)
Inhibitors Temperature pH Concentration of substrate Concentration of enzyme
Distinguish between intracellular and extracellular enzymes
Intra - work inside the cell
Extra - work outside the cell
Advantages of immobilised enzymes
- greater stability over a wider range of temperature and pH
- products are easily recovered
- products aren’t contaminated with the enzyme
- enzymes are easily added or removed
- more than 1 enzyme may be used
- enzymes can be reused
Enzymes are biological catalysts. What does this mean?
Biological - produced by cells and is a protein
Catalyst - speed up rate of reaction without being used up
What is metabolism
Series of enzyme-controlled reactions in the body
Anabolic reactions
Building up molecules
Requires ATP
Eg protein synthesis
Catabolic reaction
Breaking down molecules
Releases energy
Eg digestion of proteins
Key point about enzymes
- speed up chemical reactions
- lower the activation energy
- dont take part in the reaction
- needed in small quantities
- can be reused
- convert substrates into products
- biological catalysts
Describe the structure of enzymes
- tertiary structure that is held by Hydrogen, ionic and disulphide bonds
- creates an active site where substrate can bind
- act in aqueous environments as they’re soluble and can catalyse hydrolysis
Intracellular
Work inside the cell
Extracellular
Work outside the cell
What is an enzyme-substrate complex
Temporary complex when an enzyme binds to a substrate such that the substrates are close enough to react
What is the active site
Small region on the enzyme where the substrate binds
Lock and key model
- substrate has a complementary shape to the enzyme’s active site
- explains enzyme specificity