B1.7 Genetic Variation and Its Control

Question 1

cell

Answer 1

• A cell is the basic unit of life; all organisms are made up of cells.

Question 2

chromosomes

Answer 2

• Chromosomes are thread-like structures made of DNA found in the nucleus

Question 3

genes

Answer 3

• Genes are small sections of a chromosome that control the characteristics of an organism.

Question 4

nucleus

Answer 4

• The nucleus is a large organelle found in all cells, that contains the genetic information. (Even red blood cells once had a nucleus).

Question 5

Sexual reproduction

Answer 5

Involves two parents and there is a fusing of gametes .There is also variation among the offspring.

Question 6

Number of chromosomes

Answer 6

Humans have 26 pairs of chromosomes. In the nuclei of the gametes (sex cells) there is only a single set of chromosomes. Make and female gametes contain one set of genes.

Question 7

Asexual reproduction

Answer 7

Only involves one parent .Asexual reproduction gives rise to offspring known as clones

Question 8

Tissue culture

Answer 8

Tissue culture

* This uses small groups of cells from part of a plant to grow new plants.

Question 9

Embryo transplants

Answer 9

Embryo transplants

• This involves splitting apart cells from a developing animal embryo before they become specialised.
• The identical embryos are then implanted into the wombs of host mothers

Question 10

Adult cell cloning

Answer 10

Adult cell cloning

• The nucleus is removed from an unfertilized egg cell.
• This is replaced with the nucleus of an adult cell (eg skin cell).
• An electric shock is used to start the cell dividing to form embryo cells.
• These embryo cells contain the same genetic information as the adult skin cell.
• When the embryo has developed into a ball of cells, it is inserted into the womb of an adult female to continue its development.

Question 11

Advantages of adult cell cloning

Answer 11

Advantages:

• This could be used to clone animals with desired characteristics, eg farm animals.
• It could possibly be used to save animals from extinction.

Question 12

concerns of adult cell cloning

Answer 12

Concerns:

• People do not want human babies to be cloned.
• If this is used in farming, it produces lots of genetically identical individuals;
• If there is a change in the environment, they may all struggle to survive.

Question 13

Genetic engineering
Examples of uses in medicine:

• Vaccine production
• Production of insulin for diabetics.

Answer 13

Genetic engineering
* Genes from the chromosomes of humans and other organisms can be cut out using enzymes and transferred to cells of other organisms.

Question 14

Insulin gene in bacteria

Answer 14

The process:

• Cut out the insulin gene from the DNA of a human cell using an enzyme.
• Remove a ring of DNA from a bacterium and open it up using the same enzyme.
• Insert the insulin gene into the plasmid using another enzyme.
• Enable a bacterium to take up the altered DNA.
• Put the bacterium in a fermenter, and it multiplies many times.
• Each new bacterium contains the insulin gene.
• The bacteria produce insulin which can be extracted.