DNA replication

Question 1

DNA Replication

Answer 1

The biological process by which a cell makes an exact copy of its DNA, ensuring that each cell receives a complete identical set of genetic information

Question 2

DNA helicase

Answer 2

Unwinds the DNA breaking the weak hydrogen bonds in between nitrogenous bases

Question 3

DNA polymerase

Answer 3

Recruits nucleotides that build the DNA strand in a 5’ to 3’ direction, adds nitrogenous bases complementary to both strands.

Question 4

DNA Ligase

Answer 4

Bonds fragments of DNA together by completing any sugar - phosphate backbones

Question 5

DNA Primase

Answer 5

Adds a RNA primer ( small RNA base) that allows DNA polymerase to bind to the DNA strand

Question 6

DNA topoisomerase

Answer 6

Works at the same time as helicase as it stops the DDNA from super coiling.

Question 7

Exonnuclease

Answer 7

Remove RNA primers from the newly built strands.

Question 8

DNA replication

Answer 8

The process where a cell make an exact copy of its DNA before cell division, it ensures that both new cells have the same genetic information

Question 9

Step 1 (Unwinding the DNA)

Answer 9

• The enzyme helicase unwinds and separates the double - stranded DNA, forming a replication fork.
• Topoisomerase works ahead of the replication fork to prevent supercoiling (twisting of DNA)
• single - stranded binding proteins attach to the separated strands to prevent them from rejoining by stopping hydrogen bonds from forming.

Question 10

Step 2 (priming the strands)

Answer 10

• primase adds short RNA primers to the 3’ end of each template strand.
• these primers are necessary starting point for DNA polymerase to begin building the new strand.

Question 11

Step 3 (building of new DNA strand)

Answer 11

DNA polymerase binds to the primers and adds DNA nucleotides to build the new strands in a 5’ to 3’ direction.

a) leading strand: strand that is built continuously towards the replication folk

b) lagging strand - built in short segments moving away from the fork. The segments are called Okasaki fragment.

Question 12

Step 4 (replacing RNA primers)

Answer 12

Exonuclease removes the RNA primers from the new strands.

DNA polymerase fills in the gaps with DNA nucleotides.

Question 13

Step 5 (sealing the DNA)

Answer 13

DNA ligase joins the Okazaki fragments by forming bonds in the sugar-phosphate backbone, sealing the gaps.

Question 14

Step 6 (Results - 2 identical DNA molecules)

Answer 14

Two identical DNA molecules are formed.

Each molecule contains one original strand and one new strand — this is called semi-conservative replication.