Semi-conservative replication

Question 1

describe the steps of semi-conservative replication

Answer 1

1) DNAhelix unwinds catalysed by gyrase enzyme
2)hydrogen bonds between nucleotide bases are broken by enzyme DNA helicase
3) two single polynucleotide strands separate with exposed nucleotide bases acting as templates
4) free DNA nucleotides line up to their complimentary base paring A-T G-C
5) enzyme DNA polymerase joins new nucleotides together by phosphodiester bonds.
6)the strands twist making 2 identical DNA double helices with one new strand and one old strand

Question 2

when does DNA replication occur and why is it important?

what does it require

Answer 2

-occurs in the interphase of the cell cycle before mitosis
-important for y molecule that passes genetic info from one generation to the next-self replication
-used for growth, cell repair, cell replacement

-requires source of chemical energy (ATP)

Question 3

explain replication error and what is causes

how often does it happen?

Answer 3

-sequence of bases aren’t always matched exactly so incorrect sequence may occur in newly copied strand
=mutations

-occurs in 1 in every 10^8 base pairs