NAGE

Question 1

Which nitrogenous bases are classified as purines?

Answer 1

Adenine and Guanine

Question 2

Which nitrogenous bases are classified as pyrimidines?

Answer 2

Cytosine, thymine and uracil

Question 3

Key difference between purines and pyrimidines

Answer 3

• Purines consist of a double ring which is a larger structure compared to a pyrimidine
• Purines are derived from the pyrimidine ring attached to a imidazole ring

Question 4

Which model does DNA replication follow?

Answer 4

Semi conservative so the DNA molecule consists of one original parent strand and one newly synthesised strand

Question 5

DNA helicase function

Answer 5

• Breaks the hydrogen bonds between the complementary base pairs, separating the two polynucleotide strands to give a replication fork
• Uses the hydrolysis of ATP as a source of energy