2.5 What can go wrong with DNA?

Question 1

DNA replication, Replication, Semi-conservative replication

Answer 1

The process in which a molecule of DNA produces two exact copies of itself. The old DNA molecule unwinds and each of the chains acts as a template for the formation of a new chain. Each new DNA molecule therefore consists of one of the existing chains and one completely new one. This process is known as semi-conservative replication.

Question 2

DNA replication steps

Answer 2

1. Hydrogen bonds between the bases break, allowing the DNA to ‘unzip’
2. DNA nucleotides pair up with their complementary bases. DNA polymerase links adjacent nucleotides
3. Two identical daughter strands are created

Question 3

DNA polymerase

Answer 3

An enzyme that catalyses the joining together of individual nucleotides to form a molecule of DNA. DNA polymerase is essential to the process of DNA replication. It is also important in gene technology where it is used in the polymerase chain reaction (PCR) to produce a large number of identical copies of small pieces of DNA.

Question 4

Semi-conservative replication

Answer 4

In DNA replication, each of the two resulting DNA molecules contains one ‘old’ (conserved) strand and one ‘new’ strand

Question 5

Sickle cell anaemia

Answer 5

In the disease sickle cell anaemia, there is a mutation in the gene that codes for one of the polypeptide chains in haemoglobin

Question 6

CF gene

Answer 6

Section of DNA on chromosome 7.
The CFTR protein contains 1480 amino acids
Most common CF mutation occurs on the ATP binding site 1