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In this chapter of AS/A-level Biology, we will study Structure of Enzyme and Rate of Reaction.
Structure of Enzyme
Primary structure of an enzyme determining it’s three dimensional structure and properties [6]
- In AS/A-level Biology,The primary structure is the sequence of amino acids which determine the type of bonds
- E.g disulphide, ionic, hydrogen bonds and hydrophilic and hydrophobic properties
- Hydrophilic properties are on the outside and hydrophobic properties on the inside
- Which are determined by interactions between R groups
- These bonds determine the shape of the active site
- Which is specific
- Active sites are involved in chemical reactions between enzymes and substrates
- The shape of the active site has to be correct to allow substrate to bind to the active site
- Enzymes are globular in their 3D structure
Effect of Enzyme and Substrate Concentrations on the Initial Rates of Reactions.
Describe the effect of enzyme concentration on the initial rate of reaction [4]
- Enzymes reduce the activation energy
- This causes increased collisions of enzymes with substrates
- Many active sites are occupied
- It levels off as substrate becomes the limiting factor in AS/A-level Biology
Explain the changes in the total volume of oxygen produced over the course of the reaction [4]
- There is a faster initial rate of reaction due to the substrate not being a limiting factor
- There are enzyme substrate complexes
- Then, AS/A-level Biology explains that the volume of oxygen produced slows down because there are fewer active sites occupied
- It levels off because substrate becomes limiting
Process of DNA Replication
Describe the process of DNA replication [6]
- DNA helicase unwinds the DNA double helix
- Breaking the hydrogen bonds
- Both strands act as template strands
- DNA polymerase brings free floating nucleotides, they line up along both exposed strands
- Complementary base pairing occurs where adenine joins with thymine and cytosine binds with guanine in AS/A-level Biology
- DNA ligase reforms the hydrogen bonds
- Mononucleotides are made in condensation reactions
- Both strands will contain an original strand and a newly synthesized strand
What is semi conservative replication?
- A new DNA is synthesized, it contains a new and original strand
Great! You now understand AS/A-level Biology's enzyme and DNA replication.
