Biological Molecules - DNA Replication Flashcards
What is the purpose of semi-conservative replication?
Before a (parent) cell divides, it needs to copy the DNA contained within it
This is so that the two new (daughter) cells produced will both receive the full copies of the parental DNA
What is the importance of retaining one original DNA strand
It ensures that the new cells produced during cell division inherit all their genes from their parent cells
This is important because cells in our body are replaced regularly and therefore we need the new cells to be able to do the same role as the old ones
Replication of DNA and cell division also occurs during growth
Why does DNA replication occur?
In preparation for mitosis, when a parent cell divides to produce two genetically identical daughter cells – as each daughter cell contains the same number of chromosomes as the parent cell, the number of DNA molecules in the parent cell must be doubled before mitosis takes place
What is the process of semi-conservative replication?
The enzyme DNA helicase unwinds the DNA double helix by breaking the hydrogen bonds between the base pairs on the two antiparallel polynucleotide DNA strands to form two single polynucleotide DNA strands
Each of these single polynucleotide DNA strands acts as a template for the formation of a new strand made from free nucleotides that are attracted to the exposed DNA bases by specific base pairing
The new nucleotides are then joined together by DNA polymerase which catalyses condensation reactions to form a new strand with phosphodiester bonds
The original strand and the new strand joined together through hydrogen bonding between base pairs to form the new DNA molecule
Which scientists worked together to confirm the DNA double helix structure and the semi-conservative replication model?
Watson and Crick
Who proved Watson and Crick’s theory of semi-conservative DNA replication?
Meselson and Stahl
How was Watson and Crick’s theory of semi-conservative DNA replication proven?
They used a heavy isotope of nitrogen and a light isotope of nitrogen to prove that DNA replicates semi-conservatively.
