enzymes Flashcards
What are enzymes?
Enzymes are biological catalysts.
What do enzymes do?
They speed up the rate of chemical reactions without themselves being chemically changed at the end of the chemical reactions.
Can enzymes be reused?
Yes
Are enzymes effective in large or small concentrations?
Enzymes are effective in small concentrations.
What is a substrate?
Substrate is the molecule which an enzyme acts on.
What is the product?
Product is the result of a chemical reaction catalysed by an enzyme.
What is the active site?
It is the part of an enzyme where substrate(s) bind(s).
What is the enzyme-substrate complex?
It is formed when substrate molecule(s) bind to the active site of the enzyme.
Define catabolic reactions.
Catabolic reactions consist of chemical reactions which break down complex molecules into simpler molecules.
Define anabolic reactions.
Anabolic reactions consist of chemical reactions which build up simple molecules into complex molecules.
What are most enzymes made of?
Most enzymes are proteins with a unique 3-dimensional structure.
Where are proteins synthesized?
In ribosomes. (Refer to chapter on Cells.)
What part of the enzyme binds to the substrate?
The active site.
Why is each enzyme specific to a substrate?
Each active site can only allow specific substrate(s) to fit in.
What causes the specificity of an enzyme?
The complementary shape between the substrate and the active site.
What is activation energy?
The energy that must be supplied to the reactant molecules for them to react.
In what form is activation energy often supplied?
In the form of heat.
What happens when reactant molecules absorb thermal energy?
They move faster and collide more frequently and forcefully in the correct orientation.
How does thermal energy affect bonds within molecules?
It increases the chance that bonds will break.
Why is heating inappropriate in biological systems?
High temperatures denature proteins and kill cells.
Why can’t organisms use heating to speed up chemical reactions?
Heating speeds up all reactions
How do enzymes speed up chemical reactions?
They lower the activation energy required to start a chemical reaction.
What is the first step in an enzymatic reaction?
Effective collision between specific substrate(s) and enzyme at the correct orientation.
What forms when a substrate enters the active site? How does that help?
An enzyme-substrate complex that lowers activation energy.
