DNA replication Flashcards
Why does DNA need to replicate itself?
- Cells carries out Mitosis, forms 2 daughter cells genetically identical to the original.
- Before a cell carries out Meiosis it needs to replicate the DNA to be shared against the 4 daughter cells.
(DNA replication) - What is the first step of DNA replication?
2 strands in the DNA double helix unwinds and separates, exposing the bonds
(DNA replication) - How does the DNA double helix wind?
It uses the enzyme DNA helicase
(DNA replication) - What bonds are broken when the helix unwinds?
Hydrogen bonds
which are broken between the complementary bases so the 2 strands separate
(DNA replication) - Are there any free nucleotides in the cell?
Yes, there are free DNA nucleotides in the cell nucleus
(DNA replication) - What happens when the 2 strands separate?
The free nucleotides will line up next to the exposed bases, by complementary base pairing
(DNA replication) - What bonds form between the exposed bases?
New hydrogen bonds form between the exposed bases on the original strand and the new ones
(DNA replication) - as well as bonds, what else is formed?
New sugar phosphate back bones are formed (phosphodiester bonds form) - involves enzyme DNA polymerase
(DNA replication) - what enzyme forms the sugar phosphate back bones?
DNA polymerase
Why is it called semi conservative DNA replication?
It has one original strand and has one new strand
Does DNA in all organisms replicate the same way?
yes it does
What direction can the DNA polymerase move?
One direction (3’ to 5’)
What is the leading strand?
One of the strands is continuously replicated
What is the lagging strand?
The other strand that has to be copied in sections as it unwinds.
What is a mutation?
A change in the DNA base sequences
