DNA Replication (OCR A level biology) Questions with Correct Answers

DNA Replication (OCR A level biology)
Questions with Correct Answers
DNA replication - ANSWERSThe copying of a double stranded helix to form two
identical helicies.

When does DNA replication occur? - ANSWERSInterphase

Why does DNA replicate? - ANSWERSso a cell can divide

Where does DNA replication occur? - ANSWERSnucleus

Enzymes involved in DNA replication - ANSWERSDNA helicase and DNA polymerase

DNA helicase - ANSWERSUnzips the double helix by disrupting the hydrogen bonds
between the anti-parallel strands.

DNA polymerase - ANSWERSCreates complementary strands of DNA during
replication. It adds nucleotides to form a polynucleotide. It moves from 3' to 5'.

Semi-conservative replication - ANSWERSThe new DNA has one new strand and one
original one. The original strand acts as a template for the new strands. Both DNA
molecules formed are identical.

Steps of DNA replication - ANSWERS1) DNA helicase unzips the DNA by disrupting
hydrogen bonds.
2) Free nucleotides are attached to their complementary bases and the hydrogen bonds
reform between them.
3) Once the new nucleotides have lined up, DNA polymerase attaches them and new
phosphodiester bonds form between them.
4) All nucleotides along the whole length are joined forming two complete identical
chains, each retaining half the original DNA.

Leading strand - ANSWERSThe new continuous complementary DNA strand
synthesised along the template strand in the mandatory 5' to 3' direction.