Enzymes Flashcards
What do enzymes do?
Speed up chemical reactions by acting as biological catalysts
Where can enzyme action take place?
Intracellular
Extracellular
What does intracellular mean?
Within cells
What does extracellular mean?
Outside cells
Are enzymes proteins?
Yes
What do enzymes have which has a specific shape?
Active site
What is the active site?
Part of the enzyme where the substrate molecules bind to
Why are enzymes highly specific?
Due to their tertiary structure
What is the activation energy?
Amount of energy that needs to be supplied to the chemicals before the reaction will start
What is the activation energy often provided as?
Heat
What do enzymes do to the activation energy?
Lower the amount of activation energy that is needed
So make reactions happen at a lower temperature than they could originally
So speed up the rate of reaction
What is formed when a substrate fits into the enzyme’s active site?
Enzyme-substrate complex
What are the 2 reasons why the enzyme-substrate complex lowers the activation energy?
2 substrate molecules need to be joined, attached to enzyme holds them closer together, reducing any repulsion between the molecules so they bond more easily
Fitting into the active site puts strain on bonds in substrate so substrate molecule breaks up more easily
What is the ‘lock and key model’?
Enzyme binds to substrate if active site of enzyme is a complementary shape to the substrate
What does the ‘induced fit’ model explain?
Why enzymes are so specific and only bond to one particular substrate
What is the ‘induced fit’ model?
As a substrate binds, the active site changes shape slightly
Why do enzymes only catalyse one reaction?
Only 1 complementary substrate will fit into the active site
What is the enzyme’s active site determined by?
Enzyme’s tertiary structure
What happens if the substrate shape doesn’t match the active site?
An enzyme-substrate complex won’t be formed and the reaction won’t be catalysed
What happens if the tertiary structure of a protein is altered?
The shape of the active site will change
What can the tertiary structure of an enzyme be altered by?
pH
Temperature
What is the primary stricture of a protein determined by?
A gene
