DNA Replication & PCR

Question 1

How many Hydrogen bonds are
formed between Adenine and Thymine
bases?

Answer 1

2

Question 2

DNA polymerase catalyses formation of

phosphodiester bonds between what?

Answer 2

between 3’-OH of the deoxyribose (on the last

nucleotide) and the 5’-phosphate of the dNTP.

Question 3

At a replication fork the 5’ to 3’
strand of DNA being made continuously
is known as the….

Answer 3

Leading Strand

Question 4

When designing primers for PCR
there are a number of rules that need to
be followed to ensure that the primers
will work correctly. Which of the
following is NOT a rule that should be
adhered to when designing primers?

• The primer should be around 20-25 bases in length
• The 3’ end of the primer should end in a T or A
• The GC content should be around 50%
• Repeats (tandem repeats) of the same base should be avoided
• The primers shouldn’t be complementary to each other

Answer 4

The 3’ end of the primer should end in a T or A

Question 5

Which of these is not an enzyme
involved in DNA replication?
- DNA Primase
- DNA Ligase
- Topoisomerase
- Helicase
- RNA Polymerase

Answer 5

RNA Polymerase

Question 6

The step in a PCR carried out at 72°C

is known as the what?

Answer 6

Extension Step

Question 7

Which one of the following is not
required in a PCR reaction?
- DNA Ligase

• dNTP
• Taq Polymerase
• Oligonucleotide primers
• Mg2+

Answer 7

DNA Ligase

Question 8

Which one of these statements is
NOT true?
- Taq polymerase is isolated from the thermophillic bacteria Therms aquaticus.

• Taq polymerase is heat stable so it will not denature at temperatures used in PCR
• Taq polymerase is heat stable so it can be used to continuously cycle the 3 temperatures in the PCR reaction.
• Taq polymerase has an optimum temperature of 95C
• Taq polymerase needs small primers in order to copy the template DNA.

Answer 8

Tag polymerase has an optimum temperature of 95C