2.2 DNA replication

Question 1

What are the two main stages of cell division

Answer 1

1. Nuclear division - The process by which the nucleus divides. Two types, mitosis and meiosis
2. Cytokinesis - Follows nuclear division and is the process by which the whole cell divides

Question 2

What must happen before a nucleus divides

Answer 2

Its DNA must be replicated. This is to ensure all daughter cells have the genetic information to produce the enyzmes and other proteins that they need

Question 3

What are the four requirements for semi-conservative replication to occur

Answer 3

1. The four types of nucleotide, each with their bases of adenine, thymine, guanine and cytosine, must be present
2. Both strands of the DNA nucleotide act as a template for the attachment of these nucleotides
3. The enzyme DNA polymerase
4. A source of chemical energy is required to drive the process

Question 4

What is the process of semi-conservative replication

Answer 4

1. The enzyme DNA helicase breaks the hydrogen bonds linking the base pairs of DNA
2. As a result, the double helix separates into its two strands and unwinds
3. Nucleotides are joined together in a condensation reaction by DNA polymerase to form the ‘missing’ polynucleotide strand on each of the two original polynucleotide strands of DNA
4. Each of the new DNA molecules contains one of the original DNA strand, half the original DNA has been saved and built into each of the new DNA molecules