DNA replication and the genetic code 2.1.3 (e,f) Flashcards
what is DNA replication?
DNA is split into it’s two strand with both strands being used as a template for replication
outline DNA replication
DNA helicase unravels and unzips the DNA into two separate strands by breaking the hydrogen bonds between the nitrogenous bases
free nucleotides arrive and match with their complimentary base pairs and for hydrogen bonds
DNA polymerase forms phosphodiester bonds between the adjacent free nucleotides, forming the sugar-phosphate backbone
a new strand of DNA is attached to the original strand
role of DNA helicase
breaks hydrogen bonds between the two original strands to separate them
role of DNA polymerase
forms phosphodiester bonds between adjacent nucleotides
why is it called semi-conservative replication?
the new DNA has one original strand and one new strand
what is a mutation?
a randomly occurring error during DNA replication where the wrong base is matched leading to a change in bases
what direction does DNA polymerase run in?
3 to 5
what is the genetic code?
DNA codes for a sequence of amino acids
what is the triplet code?
every 3 bases codes for an amino acid
what is the sequence of 3 bases called?
a codon
what is a gene?
a sequence of bases which code for a protein
what are the characteristics of the genetic code?
degenerate
non-overlapping
universal
why is the genetic code degenerate?
amino acids can be coded by more than one codon
why is the genetic code non-overlapping?
there are start and stop codons which ensure that codons are read in frame
codons do not share their bases with adjacent codons
why is the genetic code universal?
same codons code for the same amino acid in all organisms
