1.2 - DNA Replication Flashcards
When is DNA copied?
During cell division.
Why is DNA unique?
It is able to replicate itself.
What is the DNA replication process for the leading strand?
- DNA unwinds and unzips as the hydrogen bonds break and the strands separate.
- A DNA primer - a short stretch of complementary DNA - attaches to the start of the piece of DNA being copied.
3. DNA polymerase adds complementary nucleotides to the 3’ end of the primer.
4. This is a continuous process until the leading strand is copied.
5. The direction of formation of the leading strand is therefore 5’ to 3’
What is the DNA replication process of the lagging strand?
- Many primers attach along the strand.
- These are extended by the DNA polymerase.
- The fragments are then joined by the enzyme ligase
- This is a discontinuous process creating the lagging strand.
What can speed up the replication process when copying a long chromosome?
Replication forks.
What 5 things must the nucleus contain to allow DNA replication?
- DNA (to act as the template)
- Primers
- A supply of the 4 types of nucleotide
- DNA polymerase and DNA ligase enzymes
- A supply of ATP (energy)
What is PCR?
A technique used to amplify specific DNA fragments.
What is the process of PCR?
1.DNA heated to 95 °C – separates original DNA strands by breaking hydrogen bonds between strands.
2.Cooled to 55 °C:
-primers target the sequence of DNA to be amplified
-primers allow a start point for DNA polymerase to start the replication
-2 different primers needed as each primer targets a different strand.
3.Heated to 72 °C – heat-tolerant DNA polymerase added.
4.Complementary free DNA nucleotides added to 3’ end. Number of original molecule now doubled.
5.Steps 1 to 5 repeated many times – DNA is amplified.
What is required for PCR to occur?
- DNA (to act as the template)
- Primers
- A supply of the 4 types of nucleotide
- DNA polymerase and DNA ligase enzymes
- A supply of ATP (energy)
- Heat tolerant DNA polymerase
- Thermal Cycler
- Buffer Solution
Give 3 uses of PCR.
- DNA profiling(forensics) - Helps to identify people with tiny piece of DNA perhaps found at a crime scene.
- Disease detection - DNA sequences that are known to indicate certain genetic disorders or diseases are amplified using PCR for the purposes of diagnosis.
- Archeobiology - Ancient DNA can be amplified and used in archeological and evolutionary research.
