Prior to cell division, _____ _______ replicates a DNA strand precisely using DNA _______
DNA Polymerase
Nucleotides
DNA polymerase needs a ______ to start replication
Primer
DNA ______ and ______ to form ______ template strands
Unwinds
Unzips
2
DNA polymerase _____ complementary _______ to the __________ 3’ end of a DNA strand. This process occurs at ________ locations on a DNA molecule
Adds
Nucleotides
Deoxyribose
Several
DNA polymerase can only _____ nucleotides in ______ direction, resulting in ______ strand being replicated continuously (________ strand) and the other strand replicated in fragments (_______ strand)
Add One One Leading Lagging
Fragments of DNA are joined together by _______
Ligase
What is required for DNA replication
DNA (to act as a template strand) Primers A supply of the 4 types of nucleotide DNA polymerase and ligase enzymes A supply of ATP (energy) Thermocycler machine or 3 water baths
Polymerase chain reaction (PCR) is a technique for the amplification of DNA ___ _______
In vitro
PCR: DNA is heated to _______ strands then cooled for _______ binding. Heat-tolerant DNA _________ then _________ the region of DNA. Repeated cycles of _______ and ________ _______ this region of DNA
Separate Primer Polymerase Replicates Heating Cooling Amplify
Examples of practical applications of PCR are;
DNA fingerprinting
Diagnosis of genetic disease
One technique that could be used in the detection of a mutation/ disease/ criminal/ father of child is _________
Electrophoresis
Make notes on DNA replication
- The DNA molecule unwinds and weak hydrogen bonds break between base pairs allowing the strand to separate (unzip)
- A primer binds to each strand of DNA
- DNA polymerase replicates a strand of DNA from free DNA nucleotides by adding complementary nucleotides to the deoxyribose (3’)
- Free nucleotides bond/ join to complementary bases (A-T and C-G)
- The leading strand is replicated continuously
- The other (lagging) strand is replicated in fragments
- Fragments are joined by the enzyme ligase
- A supply of energy in the form of ATP is required
Make notes on PCR
- PCR is a technique for the amplification of DNA in vitro. It is therefore useful in any area requiring larger samples of DNA, e.g. Forensics and Archaeology
- In PCR, primers are complementary to specific target sequences at the two ends of the region to be amplified
- Heat tolerant DNA polymerase then replicates the region of DNA
- PCR is a three step process, involving heating, annealing and extension:
- heating (95C) separates the DNA strands
- annealing (54C) is he binding of the primers which mark the start and end of the sequence to be amplified as well as preventing reattach net o the separated DNA strands
- extension (72C) of the primers to complete the complementary strand is arrived out by het stable DNA polymerase - Repeated cycles of heating and cooling amplify this region of DNA
