DNA Replication Flashcards
Why is DNA replication needed
As every time that a cell undergoes cell division, all of its DNA is copied.
What is DNA replication
The process by which DNA is copied
What happens when parent cells prepare to divide
The two strands of DNA’s double helix separate and each strand serves as a template for the creation of a new double stranded DNA molecule.
What ensures that the two new strands are identical to the original
Complementary base pairing
What is the first enzyme that is involved in DNA replication
DNA helicase attaches to the DNA molecule.
What does DNA helicase do
It causes the hydrogen bonds between complementary bases to break. This results in the two polynucleotide strands separating from each other.
What happens after the two strands of DNA separate
Free nucleotides then line up with the complementary bases on the DNA strands.
What are the free nucleotides held together by at this stage
They are held together by hydrogen bonds between complementary bases. They aren’t bonded to each other by phosphodiester bonds.
What type of nucleotides are the free nucleotides and how are they different from normal nucleotides.
They are activated nucleotides. Which contain three phosphate groups whereas a normal nucleotide only contains one phosphate group.
What is the second enzyme involved in DNA replication
DNA polymerase
What does the second enzyme do
It moves down the molecule and catalyses the formation of a phosphodiester bond between activated nucleotides.
What happens to the activated nucleotides when the phosphodiester bonds form
The activated nucleotides lose two of their phosphate groups whereas
What do the two phosphate groups that are lost provide
They provide energy for the reaction when they leave
After DNA polymerase has finished working on the DNA molecule what happens
We have two copies of the double stranded DNA molecule.
What does each new strand of DNA have
It has one strand from the original DNA molecule and one strand which is new.
