Dna Replication

Question 1

Semi conserved replication requirements

Answer 1

Adenine ,guanine, cytosine or thymine, must be present.
• Both strands of the DNA molecule act as a template for the attachment of these nucleotides.
• The enzyme DNA polymerase.
• A source of chemical energy is required to drive the process.

Question 2

Process of semi conservative replication

Answer 2

The enzyme DNA helicase breaks the hydrogen bonds linking the base pairs of DNA.
• As a result the double helix separates into its two strands and unwinds.
• Each exposed polynucleotide strand then acts as a template to which complementary free nucleotides bind by specific base pairing
• Nucleotides are joined together in a condensation reaction by the enzyme DNA polymerase to form the ‘missing’ polynucleotide strand on each of the two original polynucleotide strands of DNA.
• Each of the new DNA molecules contains one of the original DNA strands, that is, half the original DNA has been saved and built into each of the new DNA molecules (Figure 2). The process is termed
‘semi-conservative replication’.