key area 1.2 - replication of DNA Flashcards
1
Q
beginning stages of DNA replication
A
- DNA molecule unwinds
- weak hydrogen bonds break using ATP
- template strands separate to form a Y-shaped replication fork
2
Q
leading strand
A
- a primer attaches to the exposed 3’ end of the template strand
- DNA polymerase aligns free DNA nucleotides to the 3’ end of the primer (according to the base paring rule)
- DNA polymerase also causes the strong chemical bonds to form between newly added DNA nucleotides forming the completed strands
3
Q
lagging strand
A
- many primers attach to the 3’ end of the template strand as it becomes exposed
- DNA polymerase adds free DNA nucleotides to the 3’ end of the primers (according to the base pairing rule) forming many fragments
- the enzyme ligase joins the fragments together to complete the lagging strand
4
Q
basic requirements for DNA replication
A
- DNA template
- primers
- free DNA nucleotides
- enzymes (DNA polymerase + ligase)
- ATP (energy)
5
Q
requirements for PCR
A
- primers
- supply of DNA nucleotides
- DNA sample
- heat tolerant DNA (taq)
- thermocycler/thermal cycling machine
6
Q
PCR summary
A
- 92 - 98°C : the two strands of DNA separate and denature
- 50 - 65°C : allows primers to bind to the target sequence
- 70 - 80°C : heat tolerant DNA polymerase replicates the target sequence of DNA by adding nucleotides to 3’ end of original DNA
7
Q
uses of PCR
A
- solving crimes
- settle paternity suits
- diagnose genetic disorders
8
Q
amplification
A
increase the number of copies of a DNA molecule by PCR
9
Q
DNA polymerase
A
enzyme required to promote DNA replication
10
Q
ligase
A
an enzyme that joins DNA fragments to make the lagging strand
11
Q
polymerase chain reaction
A
method of amplifying sequences of DNA in vitro (outside the body)
12
Q
primer
A
short complementary strand of DNA
13
Q
specific target sequences
A
region at the end of a DNA strand complimentary to a primer
