74 WJEC Biology AS Level - Marianne Izen - 2nd Edition (1.4 Enzymes And Biological Reactions) Flashcards
What does the term metabolism refer to?
The term metabolism refers to all the reactions of the body.
What are metabolic pathways?
Reactions occur in sequences called metabolic pathways.
What are the type of reactions that occur in metabolic pathways?
- Anabolic reactions
- Catabolic reactions
What are anabolic reactions?
Anabolic reactions means building up molecules, e.g. protein synthesis
What are catabolic reactions?
Catabolic reactions means breaking molecules down, e.g. digestion.
What controls metabolic pathways?
Metabolic pathways are controlled by enzymes.
In metabolic pathways, what happens to the products of one reaction?
The products of one enzyme-controlled reaction become reactants in the next.
What are enzymes?
Enzymes are globular proteins that are catalysts.
Why are enzymes called biological catalysts?
They are called ‘biological’ catalysts because they are made by living cells.
Do enzymes and chemical catalysts share properties?
Explain.
Yes, enzymes and chemical catalysts share properties in the reactions they catalyse. These are:
They speed up reactions.
They are not used up.
They are not changed.
They have a high turn-over number
What do you mean when you say that enzymes have a high turnover number?
It means they catalyse many reactions per second.
What type of reactions do enzymes catalyse?
Enzymes only catalyse reactions that:
- are energetically favourable
- would happen anyway.
If enzymes only catalyse reactions that would happen anyway, why do you need them?
Without enzymes, reactions in cells would be too slow to be compatible with life.
What level of structure do enzymes have?
Enzymes are proteins with tertiary structure
What is the tertiary structure of enzymes?
The protein chain folds into a spherical or globular shape.
The hydrophilic R groups are on the outside of the molecule, making enzymes soluble.
What is the primary structure of an enzyme.
Each enzyme has a particular sequence of amino acids
What determines the bonds the amino acids make with each other in an enzyme?
The elements in the R groups determine the bonds the amino acids make with each other.
What are type of bonds seen in enzymes?
- hydrogen bonds
- disulphide bridges
- ionic bonds
What is the function of the bonds seen in enzymes?
They hold the enzyme molecule in its tertiary form.
What is the active site of an enzyme?
A small area with a specific 3D shape is the active site.
What is the importance of the active site?
It gives the enzyme many of its properties.
Draw the structure of an enzyme
Metabolism (Key-Term)
All the organism’s chemical processes, comprising anabolic and catabolic pathways.
Metabolic pathway (Key-Term)
A sequence of enzyme-controlled reactions in which a product of one reaction is a reactant in the next.
Enzyme (Key-Term)
A biological catalyst; a protein made by cells that alters the rate of a chemical reaction without being used up by the reaction.
Catalyst (Key-Term)
An atom or molecule that alters the rate of a chemical reaction without taking part in the reaction or being changed by it.
Active site (Key-Term)
The specific three- dimensional site on an enzyme molecule to which the substrate binds by weak chemical bonds.
Do all chemical bonds have the same strength?
Explain.
No, chemical bonds vary in strength, depending on the atoms that they join and on their chemical environment.
Hydrogen bonds are weak but if there are many of them, they have a significant binding effect.
Ionic and covalent bonds, such as the disulphide bond, are stronger than hydrogen bonds.
