3.5 Genetic modification and biotechnology

Question 1

what is gel eletrophoresis used for?

Answer 1

used to seperate proteins according to size

Question 2

What is Polymerase chain reaction (PCR)?

Answer 2

copying DNA in a lab

Question 3

What is gene transfer?

Answer 3

Cutting and pasting genes from one organism into another

Question 4

What is cloning

Answer 4

making an identical copy of cells and animals

Question 5

PCR process

6-8 mark

Answer 5

1. PCR is DNA replication in a lab, forced with heat
2. The DENATURATION process starts. DNA is placed in a test tube with heat applied for 1min at 94°C to break the hydrogen bonds between the complementary base pairs.
3. The ANNEALING process begins, DNA Polymerase is converted back into the base sequence by being cooled to 54°C for 45 seconds. The foward and reverse primers do this.
4. The EXTENSION/ ELONGATION process begins by heating the test tube back to 74°C for 2mins.
5. Taq Polymerase then reads the DNA strand and builds complementary base pairs from 5’ to 3’.
6. Complementary nucleotide bases are found in the test tube, the Taq polymerase attaches them to each primer.
7. To get the target sequences, the process must be repeated 3 times.

Question 6

Gel electrophoresis process

6-8 mark

Answer 6

1. Restriction enzymes cut the DNA into shorter fragments
2. Copies of the DNA fragments are made with PCR
3. DNA fragments are placed into wells in the agarose gel on the negative end.
4. The gel is exposed to an electric current
5. The DNA fragments move down the gel according to size.
6. This is because the DNA backbones contain negatively charged phasphate groups which are attacted to the positive electrode.
7. The smallest move further down the gel towards the positive pole due to their negative charge.
8. The final thing can then be used to compare two species’ DNA

Question 7

DNA profiling

Answer 7

comparison of DNA with gel electrophoresis
- may need to match DNA for an example of paternity testing

Question 8

Gene transfer required materials

Answer 8

Vector: A carrier for DNA
Plasmid: small loop of DNA found in bacteria cells
Restriction enzymes: cuts plasmid and DNA fragments between the DNA bases
DNA ligase: enzyme that links sticky ends of the plasmid and DNA fragment together by forming covalent bonds

Question 9

Human growth hormone (hGH)

Answer 9

• Synthesized in the pituitary gland.
• Stimulates growth of body cell

Question 10

Gene transfer (Explain the process of genetically modifying bacteria)

8 marks

Answer 10

1. An enzyme is used to remove a strand of mRNA from a sequence coding for something, for example insuline.
2. Another enzyme is used allowing cDNA to copy the mRNA
3. A restriction enzyme then cuts the cDNA at appropriate ends, forming sticky ends
4. The cDNA is then fused to the plasmid as the complementary base pairs on the sticky ends bond through hydrogen bonds
5. Ligase is then added forming covalent bonds on the phasphate backbones
6. The newly formed recombinant DNA is then put back inside a suitable bacteria such as e-coli
7. The bacteria is then cultured to allow the cells to split, causing the plasmid and DNA to replicate.
8. The insuline can then be removed

Question 11

Potential risks and benefits associated with the genetic modification of crops

8 mark

Answer 11

Question 12

Analysis of data on risks to monarch butterflies of Bt crops

Answer 12

• Bt corn is genetically modified and incorporates an insecticide producing gene from the bacterium Bacillus thuringiensis
• This insecticide is lethal to certain types of larvae, particularly the European corn borer which would otherwise eat the crop
• This negatively impacts monarch butterfly larva, as they feed exclusively on milkweed
• Wind-borne pollen from Bt corn may dust nearby milkweeds

Question 13

What are clones

Answer 13

Groups if genetically identicle organisms derived from a single original parent cell

Question 14

Examples of natural cloning

Answer 14

• Strawberry plant
• Corals
• twins

Question 15

Outline a technique used for artificial cloning

5-8 mark

Answer 15

• A technique used for artificial cloning is Somatic Cell nuclear transfer.
• A cell is taken from the udders of a Donor Sheep since they divide quickly
• The diploid nucleous is removed from the cell
• A second female sheep with different physical characteristics, but from the same genus and species is used to differenciate the baby without DNA analysis
• An egg is taken from the sheep, the haploid nucleous is removed
• The diploid and haploid nuclei are then fused with an electric shock to form a new cell which becomes an embryo.
• The embryo is then placed in a new surrugate sheep in the uterus which then grows into a baby.
• The surrugate sheep gives birth to the cloned baby which belongs to the Donor sheep.