D1.1.4 Polymerase chain reaction and gel electrophoresis Flashcards
What is the purpose of PCR?
To amplify DNA, creating millions of copies from a small sample.
What temperature is the denaturation step in PCR?
95°C.
List the key components of PCR.
- Template DNA
- Primers
- Taq polymerase
- Nucleotides (dNTPs)
- Thermal cycler.
What happens during the denaturation step?
The DNA double helix is heated to 95°C, breaking the hydrogen bonds and resulting in two single strands.
What is the role of primers in PCR?
Primers are short DNA sequences that bind to the template, marking the starting point for replication.
What happens during the annealing step?
The temperature is lowered to allow primers to bind to their complementary sequences on the single-stranded DNA.
What is gel electrophoresis?
A technique used to separate and analyze molecules like DNA based on their size, charge, or shape.
What happens during the extension step?
Taq polymerase adds nucleotides to the primers, synthesizing new DNA strands.
What is the first step in the gel electrophoresis process?
Preparation of the gel, usually made of agarose.
Why is a DNA ladder used in gel electrophoresis?
A DNA ladder contains fragments of known sizes, helping to estimate the size of the DNA bands.
What is the temperature range for the annealing step in PCR?
50-65°C.
How many times is the PCR cycle typically repeated?
20-40 times.
How does gel electrophoresis separate DNA fragments?
By applying an electric current, with smaller fragments moving faster through the gel toward the positive electrode.
What is the optimal temperature for the extension step?
72°C.
What happens to DNA in the gel during electrophoresis?
DNA, being negatively charged, moves toward the positive electrode.
What is the role of the buffer solution in gel electrophoresis?
It conducts electricity and maintains a stable pH during the electrophoresis process.
What is the gel in gel electrophoresis made of?
Usually made of agarose.
List three applications of PCR and gel electrophoresis.
- Forensic science
- Medical diagnostics
- Genetic research.
Why is Taq polymerase used in PCR?
Because it is heat-resistant and remains stable at high temperatures.
What happens to the gel after electrophoresis?
The gel is stained with a dye that binds to DNA, making the fragments visible under UV light.
