DNA Replication Flashcards
1
Q
What occurs in cell cycle before cell division?
A
- all DNA replicates to provide a copy for the new cell
- interphase s phase
2
Q
What is the way that DNA replicates?
A
- semi conservative
3
Q
What is semi conservative replication?
A
- in the daughter DNA one strand is from the parental DNA and one strand is newly synthesised
4
Q
What is step one of DNA replication?
A
- Enzyme DNA helicase breaks hydrogen bonds between the complementary base pairs between the two strands within a double helix causing the DNA double helix to unwind
5
Q
What is step two of DNA replication?
A
- each of the separated parental DNA strands act as a template
- free floating DNA nucleotides attracted to their complementary base pairs on the template strands of the parental DNA
6
Q
What is step three of DNA replication?
A
- DNA polymerase joins adjacent DNA nucleotides together to form phosphodiester bond by a condensation reaction
7
Q
What is step four of DNA replication?
A
- each daughter DNA molecule now has one original strand and one newly synthesised strand
8
Q
What does semi conservative replication of DNA ensure?
A
- genetic continuity between generations of cells
9
Q
What does Meselson and Stahls experiment prove?
A
- Watson and cricks semi conservative hypothesis
10
Q
What does Meselson and Stahls experiment involve?
A
- growing bacteria in mediums containing two different isotopes of nitrogen
- 14N is lighter and 14N is heavier
11
Q
How were the nitrogen isotopes incorporated into the DNA nucleotides?
A
- to make nitrogenous bases
12
Q
How was the DNA separated according to its density?
A
- using centrifuge
13
Q
Semi conservative replication hypothesis
A
- each replicated DNA molecule contains one of the original DNA strands strand and one newly synthesised DNA strand
14
Q
Conservative replication hypothesis
A
- original DNA remains intact following DNA replication and the two newly synthesised strands of DNA join together
15
Q
Isotope
A
- different forms of an element in which the proton and electron number is same but different number of neutrons
