DNA REPLICATION Flashcards
What is the process by which a DNA molecule makes an identical copy of itself?
DNA replication
What is the name of the short RNA primer that initiates DNA synthesis?
Primase
During DNA replication, which enzyme is responsible for joining the Okazaki fragments on the lagging strand?
DNA ligase
What is the name of the process where the two strands of DNA separate during replication?
DNA unwinding
What is the term for the Y-shaped structure that forms during DNA replication?
Replication fork
What is DNA replication?
DNA replication is the process by which DNA makes a copy of itself during cell division.
What is the function of DNA polymerase in DNA replication?
DNA polymerase is the enzyme responsible for synthesizing new DNA strands by adding nucleotides to the growing DNA chain.
What is the function of primers in DNA replication?
providing a starting point for DNA polymerase.
What is the leading strand in DNA replication?
The leading strand is the DNA strand that is synthesized continuously in the 5’ to 3’ direction.
What is the lagging strand in DNA replication?
The lagging strand is the DNA strand that is synthesized discontinuously in the 5’ to 3’ direction, forming Okazaki fragments.
What is the role of DNA ligase in DNA replication?
DNA ligase is the enzyme that joins Okazaki fragments together on the lagging strand, sealing any gaps in the DNA.
What are the consequences of errors in DNA replication?
Errors in DNA replication can lead to mutations, genetic disorders, or cell death.
What is a primer
A short strand of nucleotides which binds to the 3”end of the template dna strand allowing DNA polymerase to add dna nucleotides
DNA is replicated Prior to what
Cell devision
What does DNA polymerase need to start replication
Primers
What are the requirements for DNA replication
Original DNA template
Free DNA Nucleotides
DNA polymerase
primers
Ligase
Stage 1 of DNA replication
The dna is unwound and unzipped, hydrogen bonds between bases are broken to form two template strands.
This process occurs at several locations on a DNA molecule
Stage 2 of DNA replication
1.DNA polymerase will add the free DNA Nucleotides using complementary base pairing to the 3” end of the new dna strand which is forming.
2 . The leading strand is synthesised continuously. DNA Polymerase adds nucleotides to the 3”ended strand in a 5”-3” direction.
3. The lagging strand is synthesised in fragments, As DNA Polymerase can only add dna nucleotides in a 5”- 3” direction. The fragments are then sealed together by the ligase enzyme
Third stage of DNA REPLICATION
Two new strands twist to form a double helix, each is identical to the original strand.
What is PCR
The amplification of DNA in vitro ( in glass )
Requirements of PCR
DNA
Complementary primers
Thermal cycler
Heat tolerant polymerase
Nucleotides
Process of PCR
- DNA is heated to 92-98 degrees Celsius, to denature the DNA and separate the two strands
- DNA is cooled between 50-65 degrees c to allow primers to bind to the target DNA Sequences
- Complementary primers are added, which are complementary to the target sequences at the two ends of the region to be amplified
- DNA heated to between 70-80 dc, tolerant dna polymerase added. Which replicates the region of DNA to be amplified. Two strand are formed
- Repeated cycles of heating and cooling amplify the target region of DNA
Practical applications of PCR
Solve crimes
Settle paternity suits
Diagnoses genetic disorders
