MODULE 6: Genetic Change

Question 1

SCNT?

Answer 1

Somatic Cell Nuclear transfer

Question 2

SCNT Process

Answer 2

1. Remove an egg from a donor female sheep
2. Remove the nucleus from the egg
3. Add a nucleus of a somatic cell from another sheep to the empty egg cell.
4. Electricity is often used to help fuse the enucleated donor egg cell and the somatic cell together.
5. Specific chemicals are used to help stimulate mitosis.
6. Grow the cell in vitro until it is a Blastocyst (5 days old)
7. Place the Blastocyst in the Surrogate Ewe
8. Surrogate Ewe gives birth to clone Ewe

Question 3

SCNT Example

Answer 3

Dolly the Sheep & Starbuck the stud

Question 4

Recombinant DNA?

Answer 4

Gene Cloning

Question 5

Recombinant DNA Process

Answer 5

1. A circular piece of DNA (a plasmid) is removed from a bacterium and cut open with a restriction enzyme (creating ‘sticky ends’)
2. The desired gene (and regulators) are ‘cut out’ of a source species using the same restriction enzyme (so it has the same ‘sticky ends’ as the plasmid)
3. The ‘sticky ends’ of the open plasmid and ‘cut out’ gene combine using complementary bases
4. A DNA ligase enzyme seals (anneals) the plasmid and ‘cut out’ gene together.
5. The recombinant plasmid is inserted into the bacterium.
6. The Bacterium reproduces asexually, creating more bacteria with the recombinant DNA.

Question 6

Exons

Answer 6

Exons are coding DNA segments that translate directly to amino acids and subsequently proteins . Mutations that occur here have an effect on the organisms.

Question 6

Recombinant DNA Example

Answer 6

Insulin

Question 7

Introns

Answer 7

Introns are non - coding DNA segments that amount to 98% of DNA in eukaryotic nucleotides; they are not used in the final process of translation. Mutations that occur here have no effect on the organisms.

Question 8

3 types of mutagens

Answer 8

1. Electromagnetic radiation sources (PHYSICAL)
2. Chemicals (CHEMICAL)
3. Naturally occurring mutagens (BIOLOGICAL & NON BIOLOGICAL)

Question 9

Electromagnetic radiation mutagens (PHYSICAL) - Example

Answer 9

Ultraviolet light causes mutations in skin cells resulting in melanoma (skin cancer).

Question 9

Chemical mutagesn (CHEMICAL) - Example

Answer 9

Free radicals from Tobacco smoke (mutagen) causes lung cancer.

Question 10

Naturally occurring mutagens (BIOLOGICAL & NON BIOLOGICAL) - Example

Answer 10

Naturally occurring Biological mutagen:
End products of metabolism e.g. nitrosamines (nitrates + amines in meat combine under grilling, frying heat conditions)

Naturally occurring Non-Biological mutagen:
Mercury - altering DNA

Question 11

Somatic Mutations: Effect on organism and Example

Answer 11

If the error is not repaired it will pass onto daughter cells during mitosis and potentially throughout the tissue. (Somatic mutations cannot be passed onto offspring)

Example: Melanoma
Ultraviolet light causes mutations in skin cells resulting in melanoma (skin cancer).

Question 12

Germline Mutations: Effect on organism and Example

Answer 12

Germline mutations can be passed onto offspring. When a gamete carrying a mutation fuses with another gamete to form a zygote the mutation is replicated in every cell as it divides and grows, affecting all the cells in the child’s body.

Example: Haemophilia
Haemophilia can result from a germline mutation on the X chromosome. It results in impaired blood clotting.

Question 13

3 types of single base substitution

Answer 13

1. Silent - Still codes for the same amino acid
2. Nonsense - Creates a stop codon
3. Missense - Creates a different amino acid (functionality change in protein.)

remember Single base Deletion and insertion and frameshift causing gene mutation

Question 14

Chromosomal mutation types: affecting chromosome structure (4)

Answer 14

Deletion: Deletion of part of a chromosome.
Duplication: Duplication of part of a chromosome.
Inversion: Inversion of part of a chromosome.
Translocation: Translocation from one chromosome to another

Question 15

Chromosomal mutation types: affecting number of chromosome (3)

Answer 15

Trisomy: Extra Chromosome
Deletion: Missing Chromosome
Polyploidy: Entire genome duplicate

Question 16

Artificial insemination process and outcome

Answer 16

1. Artificial vagina is used to collect male gametes
2. Insemination rod is used to insert semen (male gametes) into the uterus (transfer male gametes to female).

Used to promote favourable characteristics the favour humans in some way in the offspring. Can either increase or decrease the biodiversity of the population.

Question 17

Artificial Pollination process and outcome

Answer 17

1. The anthers on flower A are cut to prevent self pollination
2. A brush is used to collect pollen (male gametes) from flower B
3. The pollen on the brush is transferred to the stigma of flower A.

Artificial pollination promotes desired traits selected by humans in plants. Can either increase or decrease the biodiversity of the population.

Question 18

Example of a biotechnology - Ethical Issues/Social Implications.

Answer 18

Industry: Recombinant DNA - Transgenic Specific

Example:
Spider-goat: Produces protein for spider silk in milk which is used in clothing.

Benefits:
Increases the reproductive capacity of an animal
These species can be toxicity sensitive, used for chemical safety testing.

Ethical issues:
Any side effects that will cause suffering to the animal? (animal welfare)
Is it right to take a gene of a species to create a new species?
Will transgenic species radically change the direction of evolution?
Risk of breeding with populations in the wild.

Biodiversity:
Increases biodiversity due to creating a new species.
The gene of one species inserted into another species, will become part of that organism’s germline genome if it is to be inherited by subsequent generations.