B5 - enzymes Flashcards
(17 cards)
What are enzymes?
Enzymes are proteins that function as biological catalysts.
What is a biological catalyst?
A substance that speeds up chemical reactions without being used up.
What is a substrate?
The substance upon which an enzyme acts.
What is the active site?
The region of an enzyme where the substrate binds.
Why is the active site important?
It has a complementary shape that fits a specific substrate.
What happens when a substrate binds to an enzyme?
An enzyme-substrate complex is formed and the reaction occurs.
What happens to enzyme activity as temperature increases (initially)?
The rate increases due to more kinetic energy and more frequent effective collisions.
What is the optimum temperature?
The temperature at which enzyme activity is highest.
What happens to enzymes at temperatures above the optimum?
They become denatured and the active site loses its complementary shape.
Why does enzyme activity decrease when enzymes denature?
Because the enzyme-substrate complex can no longer form.
What is denaturation?
A structural change in the enzyme that causes the active site to lose its shape.
What is the effect of pH on enzyme activity?
Each enzyme has an optimum pH at which it functions best.
What happens when pH is too high or too low for an enzyme?
The active site changes shape and the enzyme denatures.
Why is the active site’s shape important?
It determines whether the enzyme can bind with its specific substrate.
What happens to the rate of reaction if the active site is no longer complementary?
The rate of reaction decreases because the substrate can’t bind.
What is the effect of increasing substrate concentration on enzyme activity?
The rate increases until it reaches a maximum, then plateaus.
What does a plateau in a graph of enzyme activity indicate?
That all enzyme active sites are occupied; the reaction rate can’t increase further.
