DNA Replication Flashcards
When does DNA replication occur?
Interphase
What does DNA replication produce?
Two exact replicas of the DNA model
What does the new DNA molecules look like?
Each new chromosome consists of two identical chromatids and are attached at the centromere
What bonds hold nucleotides together?
Hydrogen
What is the role of helicase?
Unwinds and unzips DNA
What are the SSBP for?
To stop the strands from joining and from folding over one another
How many template strands are there
2
What does RNA primase do?
Synthesises RNA primers that are complementary to the DNA template
What is the role of DNA polymerase III?
Catalyses the addition of free nucleotides complementary to the template.
What direction do new strands HAVE to be made in ?
5-3
What is the leading strand?
The Strand of DNA in which runs 5-3
What is the lagging strand?
The strand of DNA which runs 3-5
What happens with the lagging strand?
It must be built backwards from the position of the RNA primer. These short fragments are known as Okazaki fragments
What is the role of DNA polymerase I?
To remove RNA primers and replace them with DNA
What is the role of ligase?
Joins neighbouring fragments together
Explain semi-conservative
Replicated DNA will contain one old and one new strand of DNA this meaning the replication is semi conservative
Why is DNA replication nesscary?
It is the first step in cell divison for both mitosis and meisos
What is the replication fork?
The point in which each strand goes in either direction.
What sort of strand is used as a template?
The parent strand
How much genetic information does the new chromsome have in comparison with the original?
Double
What is the lagging strand formed in?
Fragments
Summarise in steps the process of cell division
- Helicase unwinds the parental DNA
- DNA polymerase III catalyses the addition of free nucleotides complementary to the template.
- Dna polymerase I cuts out RNA primer and replaces with DNA
- Ligase joins neighbouring fragments
Which are the purines?
Adenine and Guanine
What are the Pyrimidines
Thymine and Cytosine (Uracil)
How many bonds does A-T have
2
How many bonds does G-C have?
3
What phase is interphase in?
S
