AS-LEVEL AQA BIOLOGY NOTES
TOPIC 7: dna replication
- DNA double helix unwinds and “unzips”; the hydrogen bonds between base pairs are broken. This process is brought about by an enzyme called DNA helicase.
- The exposed nucleotide bases act as a template for assembly of the new DNA strand.
- Free nucleotides move towards these exposed bases according to the base pair rule.
- An enzyme called DNA polymerase binds the nucleotides together with covalent bonds, forming the new sugar-phosphate backbone.
- This process occurs to both exposed strands, resulting in 2 daughter DNA strands.
DNA replication
- ensures the preservation of genetic information stored in DNA
- Important as the structure and functions of proteins coded according to DNA relies entirely upon the correct sequences being copied
- Some mutations occur very infrequently and randomly
- These might not result in a phenotypic change, but sometimes can have life-altering consequences