Unit 5 - enzymes Flashcards
What is a substrate?
A reactant in an enzyme-catalysed reaction. Has specific shape which fits perfectly into an enzyme’s active site.
What is the lock-and-key method?
When the substrate attaches to the enzyme in a particular way because their shapes are complementary.
What is catalysis?
The acceleration of a chemical reaction by a catalyst.
What is the active site?
A specific region of an enzyme where catalysis happens
What is denaturation and what is it caused by?
The process in which the shape of an enzyme and its active site is altered permanently due to too high/too low PH or temperature. This means the substrate will no longer fit into the active site, and therefore the reaction cannot happen.
What is the function of an enzyme?
To catalyze a reaction, so that it takes place more quickly
What does an enzyme showing specificity mean?
Each type of enzyme only works for one reaction with a very small number of reactants.
What is it called when an enzyme and substrate fit together?
Enzyme-substrate complex
What does the shape of an enzyme molecule depend on?
- Sequence of amino acids - cannot be changed unless digested with very hot acid or certain enzyme
- Attractive forces between different parts of the molecule - can be changed, weakened or broken.
How does PH affect enzymes?
Changes in the PH alter the forces of attraction between different parts of the enzyme molecules. There is an optimum PH, when the rate of an enzyme-catalyzed reaction is greatest. If the PH is bigger or smaller than that, the enzyme undergoes denaturing. Often, the optimal PH will reflect where the enzyme can be found (e.g. acidic - stomach, slightly alkaline - mouth)
What must happen for a chemical reaction to occur?
The reactant particles must collide and the collision must have enough energy. There will be no reactions if particles don’t collide and if they don’t have kinetic energy. A collision that results in a chemical reaction is described as an effective collision.
What is an enzyme?
A protein that functions as a biological catalyst (substance that increases the rate of a reaction)
Name 3 types of enzymes, where it’s made, where it works & purpose
- Amylase - made in salivary gland and pancreas, work in the mouth and small intestine. Breaks down starch into reducing/simple sugars.
- Protease - made in and works in the stomach and small intestine. Breaks down proteins into amino acids.
- Lipase - made in pancreas, work in small intestine. Breaks down fats into fatty acids and glycerol.
How does increasing the temperature affect the rate of enzyme-catalyzed reactions?
As temperature increases, particles gain kinetic energy and move faster. This makes them more likely to collide with each other. As a result of this, the rate of reaction increases. Enzyme activity is highest at optimum temperature.
How can an enzyme denature at temperatures above optimum?
High temperatures cause attractive forces between different parts of the enzyme molecule to weaken or break.
