3.5 biotechnologies

Question 1

what does PCR stand for?

Answer 1

Polymerase Chain Reaction

Question 2

polymerase

Answer 2

an enzyme used in DNA replication; synthesizes long chains of polymers or nucleic acids

Question 3

what does PCR do?

Answer 3

Makes multiple copies of DNA fragments so that they can be analyzed

Question 4

steps of the polymerase chain reaction (6 steps)

Answer 4

1. Free DNA nucleotides, DNA primers, and Taq polymerase are added to the DNA sample. Placed in the thermal cycler (PCR machine).
2. Denaturation: Sample heated (95°C), DNA strands are separated (H-bonds broken)
3. Sample cooled (55°C)
4. Annealing: Primers anneal (H-bond) to template strands (at 3’ end).
5. Elongation: Taq polymerase builds complementary strand (in a 5’ → 3’ direction).
6. Repeat for 20-30 cycles.

Question 5

why use PCR?

Answer 5

To create large amounts of DNA fragments for:
- DNA profiling
- Recombination
- Genetic research

Question 6

gel electrophoresis

Answer 6

Separates nucleic acids (or proteins) based on their size.
Measures their rate of movement through a gel medium.

Question 7

process of gel electrophoresis (5 steps)

Answer 7

• Samples of DNA (or RNA or proteins) are placed in the wells
• Because it is [-vely] charged, the DNA travels through the gel in the direction of the current. The gel slows them.
• Large molecules are slowest and stay nearer to the wells.
• To see the DNA samples, they are often stained with a fluorescent dye
• A DNA marker is placed in the first well. This contains DNA of known lengths. It will allow you to estimate the size of the other DNA fragments in the other wells.

Question 8

DNA profiling

Answer 8

Aka. DNA fingerprinting

The analysis of a small amount of genetic material. Used for identification.

Question 9

applications of DNA profiling

Answer 9

Forensics investigations
Paternity tests
Species identification

Question 10

process of DNA profiling (5 steps) (both PCR+gel electrophoresis)

Answer 10

• Fragments of DNA are amplified using PCR
• Specific restriction enzymes cut the DNA into fragments (fragment lengths are different amongst individuals)
• The fragments are tagged with fluorescent markers so they can be seen.
• Fragments are separated using gel electrophoresis.
• Banding patterns of individuals are compared.