5.1 Enzyme Action (Cambridge (CIE) O Level Biology): Flashcards
Exam code: 5090
1/200Still learning
Know0
- FrontEnzymes
Define an enzyme.
Was this flashcard helpful?
Cards in this collection (20)
Define an enzyme.
A biological catalyst made of protein that speeds up the rate of a chemical reaction without being used up.
Define a catalyst.
A substance that increases the rate of a chemical reaction and is not changed or used up by the reaction.
Enzymes are biological catalysts made from the molecule .
Enzymes are biological catalysts made from the molecule protein.
Why are enzymes essential to living organisms?
They keep the rates of all metabolic reactions fast enough to sustain life.
Define the active site.
The part of an enzyme that binds to the substrate; it has a shape complementary to the substrate.
Define the enzyme-substrate complex.
The structure formed when a substrate binds to the active site of an enzyme.
The reactant that an enzyme acts on is called the .
The reactant that an enzyme acts on is called the substrate.
What happens to an enzyme after its product is released?
It is unchanged and free to bind to a new substrate and catalyse the reaction again.
True or False?
Enzymes are used up during the reactions they catalyse.
False.
Enzymes are catalysts — they are not used up and can be reused.
In order, what are the three stages of enzyme action?
Substrate binds to the active site → forms an enzyme-substrate complex → product is formed and released.
Why is each enzyme specific to one substrate?
Its active site has a shape complementary to only that substrate, because the enzyme is a protein with a specific 3D shape.
Define the lock and key hypothesis.
A model of enzyme action in which the active site (lock) has a complementary shape to only one substrate (key).
In the lock and key model, the active site is the lock and the is the key.
In the lock and key model, the active site is the lock and the substrate is the key.
True or False?
An enzyme's active site and its substrate are exactly the same shape.
False.
They are complementary (opposite) shapes, not the same shape.
What determines the specific shape of an enzyme's active site?
The particular combination of amino acids that makes up the protein.
The active site of an enzyme has a shape that is to its substrate.
The active site of an enzyme has a shape that is complementary to its substrate.
Why can't one enzyme catalyse many different reactions?
Its active site fits only one specific substrate, so it can only catalyse that substrate's reaction.
Define specificity.
The property of an enzyme whereby it acts only on one particular substrate (or type of substrate).
True or False?
Different enzymes have different active site shapes because they have different amino acid sequences.
True.
A different combination of amino acids gives a different 3D shape, and so a different active site.
What is a common mistake to avoid when describing enzyme specificity?
Saying the enzyme and substrate are the same shape — they are complementary shapes.
Sign up to unlock flashcards
or