1.2 Replication of DNA

Question 1

What enzyme replicates DNA?

Answer 1

DNA Polymerase

Question 2

What is a primer?

Answer 2

A short strand of nucleotides which binds to the 3’ end of the template DNA strand allowing polymerase to add DNA nucleotides

Question 3

To which end does DNA polymerase add new nucleotides to?

Answer 3

The deoxyribose 3’ end

Question 4

What happens at the start of DNA replication?

Answer 4

DNA is unwound and hydrogen bonds between bases are broken to form two template strands.

Question 5

Why are 2 strands of DNA replicated differently?

Answer 5

DNA polymerase can only add DNA nucleotides in one direction, resulting in the leading strand being replicated continuously and the lagging strand replicated in fragments

Question 6

What enzyme joins together the okazaki fragments in the lagging strand?

Answer 6

ligase

Question 7

What does PCR do?

Answer 7

Amplifies DNA using complementary primers for specific target sequences

Question 8

What happens at the first step of PCR?

Answer 8

DNA is heated to between 92 and 98°C to separate the strands

Question 9

What happens at the second step of PCR?

Answer 9

DNA is cooled to between 50 and 65°C to allow primers to bind to target sequences.

Question 10

What happens at the third step of PCR?

Answer 10

DNA is heated to between 70 and 80°C for heat-tolerant DNA polymerase to replicate the region of DNA

Question 11

What are some practical applications of PCR?

Answer 11

PCR can amplify DNA to help;
-Solve crimes
-settle paternity suits
-diagnose genetic disorders