DNA Replication

Question 1

Is DNA replication conservative?

Answer 1

DNA replication is semi conservative.

it retains a parent strand in each new double strand of DNA.

Question 2

Is DNA replication Continuous or Discontinuous?

Answer 2

can be both continuous and discontinuous using okazaki fragments (short newly synthesised DNA strands)

Question 3

Origin of Replication

Answer 3

Area of the DNA where DNA replication begins.

Question 4

Replication fork

Answer 4

Y-shaped region where DNA seperates and leading and lagging strands can be synthesised.

Question 5

Helicase

Answer 5

Unwinds the DNA template at the replication fork

Question 6

Single stranded proteins

Answer 6

Bind to DNA preventing it from reanealing

Question 7

DNA topoisomerases

Identify drug that inhibits Prokaryote enzymes

Answer 7

Create a single or double stranded break in the helix to help add or remove supercoils.

Fluroquinolones (ciprofloxacin) bind to II/IV topoisomerases inhibiting prokaryote DNA replication.

Question 8

DNA Primase

Answer 8

Makes RNA primer for DNA polymerase to initiate replication.

Question 9

DNA Polymerase III

Answer 9

Prokaryote only, Elongates DNA strand by adding deoxy nucleotides to 3’ end (5’–>3’ synthesis). elongates till reaches the lagging strand of the primer preceeding it. Proof reads in 3’–> 5’ direction.

Question 10

DNA polymerase I

Answer 10

Degrades RNA primer and replaces it with DNA. 5’–>3’ syntehsis with excision of RNA primer.

Question 11

DNA ligase

Answer 11

Catalyzes the formation of phosphodiester bond within a double stranded DNA. (Joins up okazaki fragments)

Question 12

Telomerase

Answer 12

RNA dependent DNA polymerase that adds DNA to 3” ends of chromosomes to avoid loss of genetic material at end of replication.