3.9 DNA Replication Flashcards
What is DNA replication
Having new daughter cells be identical to the original parent cells through the double helix separating and copied to form the new cells.
What must happen in order for DNA replication to happen
The hydrogen bonds must be broken between the helix so the 2 strands can separate
What is semi-conservative replication
When free DNA nucleotides pair with the complementary base pairs (which have been exposed as separate strands because the double helix has been broken) hydrogen bonds join between them.
Through this 2 new nucleotides are produced. Each one consists of one old strand of DNA and one new strand; ‘semi-conservative’ = ‘half the same’
What enzyme causes the double helix to separate
DNA helicase (goes along the backbone and catalyses reaction of break the hydrogen bonds)
What role does DNA polymerase play in DNA replication
It catalyses the formation of phosphodiester bonds between nucleotides
How can replication lead to mutations
If the original base sequence is copied incorrectly, it will cause a change in the new strand, leading to a mutation
What is the genetic code?
When DNA codes for a sequence of amino acids which make certain proteins
What’s a codon in the genetic code
3 bases are grouped together making a codon (triplet code)
What does a codon code for
one amino acid
What is a gene
A section of DNA that contains all the codons needed to make an entire protein
How many possible combinations for one codon is there
64 (4x4x4 or 4^3)
How many stop codons are there and what do they do
- They signal the end of a sequence
Why is the genetic code degenerate
Because there are more codons than amino acids, multiple codons can code for the same amino acid
