Replication

Question 1

Explain the process of DNA Replication

Answer 1

1. 2 complimentary strands of DNA are separated by the enzyme DNA helicase breaking the weak hydrogen bonds (each exposed strand of nucleotide serves as a template for a new strand
2. Explain Leading strand
3. Explain lagging strand
4. AS the two strands are being produced that begin to twist into double helix shape - they are now two double stranded DNA molecules (an exact replica)

Question 2

Why is replication semi conservative

Answer 2

each DNA molecule made consist of one old strand (parental strand) and one ‘new’ strand (daughter strand)

Question 3

Explain the leading strand

Answer 3

1. A short primer (RNA sequence) attaches to the DNA where replication will begin.
2. The enzyme polymerase III attaches free floating nucleotides complimentary to the exposed template DNA strand continuously in the 3’ to 5’ direction (correct direction)

Question 4

Explain the lagging strand

Answer 4

1. a number of short primers (RNA sequence) are attached in several places along the lagging strand
2. Polymerase III attaches free floating DNA nucleotides in between these primers, discountinously in the 3’ to 5’ directions, creating okazaki fragments

Question 5

Explain the end step of both the leading and lagging strands

Answer 5

1. Another enzyme called polymerase I removes RNA primers and replaces them with DNA nucleotides
2. Ligase joins okazaki fragments together