Enzymes Flashcards
What is an enzyme?
An enzyme is a biological catalyst. A catalyst is used to speed up a reaction but does not take part in the reaction.
What is an active site?
It is the part of the enzyme where the substrate binds and undergoes the reaction where the substrate is converted into a product.
What is the lock and key model?
The lock and key model is where the shape of the active site of the enzyme means that each type enzyme is only made to catalyse one type of substrate.
What is the induced-fit model?
Where the active site can slightly change to fit a substrate which means that an enzyme can catalyse a wider range of substrates.
What is the effect of temperature on enzyme activity?
The warmer the temperature, the faster enzymes catalyse a reaction because warmer temperature causes the reacting particle to move more which means they collide more frequently. This happens up to the optimum temperature in which the rate of reaction is the fastest. After this point the enzyme will denature. (approx between 40-45 degrees)
What is the effect of pH on enzyme activity?
Each enzyme has its own optimum pH and it is different depending on which enzyme it is. The enzyme is denatured when outside the optimum range.
e.g. stomach enzyme needs to be acidic as the stomach is naturally acidic therefore that particular enzyme has an optimum pH range of 2.
Why do enzymes denature?
Because the bonds in the active site are broken which change the shape of the active site which means it cannot fit the substrate anymore thus denaturing it.
What is the effect of substrate concentration?
More substrate - faster reaction
until the point where the enzymes run out.
What do co-enzymes do?
Co-factors/Co-enzymes help the substrate bind more tightly to the active site
What do inhibitors do?
Inhibitors are substrates that prevent enzymes from catalysing reactions. (Poisons)
What are the two ways inhibitors can work?
block the active site of the enzyme by binding to it
Bind to another part of the enzyme to alter the shape of the active site so that it can no longer bind to the substrate.
(heavy metals e.g. mercury, lead)
