Gene Therapy (2)

Question 1

What is gene therapy?

Answer 1

Gene therapy is an experimental genetic engineering technique that replaces a faulty gene or adds a new gene in an attempt to cure disease or improve the body’s ability to fight disease,

Question 2

If a mutated gene causes a necessary protein to be faulty or missing, gene therapy may be able to introduce a normal copy of the gene to ____ the function of the protein.

Answer 2

restore

Question 3

How are new genes introduced into the body?

Answer 3

Vectors such as viruses are used to deliver the gene into the cells of the body. The viruses are treated so they cannot cause disease in the patient.

Question 4

Gene therapy may be used in the future for treating a wide range of diseases including…(6)

Answer 4

cancer, cystic fibrosis, heart disease, diabetes, haemophilia and AIDS.

Question 5

Researchers must, however, overcome technical challenges before gene therapy will be a practical approach to treating disease. For example, scientists must: (2)

Answer 5

• find better ways to deliver genes and target them to particular cells.
• ensure that new genes are precisely controlled by the body.

Question 6

What are the two methods of delivery?

Answer 6

Direct Delivery

Cell-based delivery

Question 7

What is direct delivery?

Answer 7

The vector can be injected or given intravenously (by IV) directly into a specific tissue in the body, where it is taken up by individual cells.

Question 8

What is cell-based delivery?

Answer 8

A sample of the patient’s cells can be removed and exposed to the vector in a laboratory setting. The cells containing the vector are then returned to the patient. If the treatment is successful, the new gene delivered by the vector will make a functioning protein.

Question 9

For thousands of years genetics has made an impact on agriculture. By means of ____ selection, farmers can control the reproduction of their plants so that each new generation has as many of the parents ’_____ genes as possible.

Answer 9

artificial

beneficial

Question 10

True or false

Selective breeding is a kind of genetic engineering.

Answer 10

True

Question 11

How has selective breeding helped crops? (3)

Answer 11

By selective breeding,

• the yield of the major cereal crops has been increased
• crops have become more resistant to disease
• the nutritional value of fruits and vegetables has been enhanced.

Question 12

Define transformation.

Answer 12

Brought about by the uptake of introduced, the change in a cell or organism foreign DNA

Question 13

Why are conventional plant breeding methods inferior to geentic engineering?

Answer 13

• Conventional plant breeding methods can be slow and unpredictable. By genetic engineering, the exact desired trait can be created in one generation with great accuracy.
• Conventional plant breeding can only combine closely related plants. The engineering of plants enables scientists to take any gene from any living organism and introduce it into a plant.

Question 14

What is the resulting transformed or transgeneic plant referred to as?

Answer 14

The resulting transformed or transgenic plant is referred to as a genetically modified organism (GMO) and the inserted gene is called a transgene

Question 15

What is a transgenic organism?

Answer 15

An organism that develops from a cell with recombinant DNA

Question 16

What knowledge has been passed down from generation to generation? (3)

Answer 16

The indigenous knowledge of
- how to manipulate crops,
- how-to resources
- how to improve the diagnosis and treatment of plant and animal diseases
has been passed down from generation to generation.

Question 17

What does transgenic technology enable plant breeders to do? (2)

Answer 17

• Transgenic technology enables plant breeders to identify and isolate genes that control a specific trait from a wide range of living sources and artificially insert them into other organisms which will then have the required traits.
• This has enabled plant breeders to do what they have always done to generate more useful and productive crop varieties containing new combinations of genes. This is done, however, in a much faster and more controlled way than by traditional cross-pollination and selective breeding techniques.

Question 18

What are the two views of genetic engineering and conventional agricultural methods? (2)

Answer 18

• On the one hand therefore genetic engineering and conventional agricultural methods may be seen as complementary.
• On the other hand, transgenic technology may be seen as a dramatic departure from conventional agriculture, since it gives scientists the power to move genetic material between organisms that could not be bred through conventional means.

Question 19

To achieve useful results, therefore, it needs both the ____ knowledge of classical plant breeding methods as well as the information derived from ______.

Answer 19

indigenous

genomics

Question 20

There are two main methods of transforming plant cells and tissues: (2)

Answer 20

1. The ‘gene gun’ method (also known as microprojectile bombardment or biolistics method) is a technique that has proved quite effective in plant engineering. In this technique, pellets of metal (usually tungsten) coated with the desirable DNA are fired into plant cells. Those cells that take up the DNA may be cloned and then allowed to grow into new plants, producing vast numbers of genetically identical crop plants.
2. Recombinant DNA techniques have allowed a much more controlled way of introducing new genetic material into the plants, as described below.

Question 21

The Ti plasmid from soil bacteria, Agrobacterium tumefaciens, causes tumors (galls) in plants. The fact that these bacteria have the ability to invade and naturally infect plant cells has been used as a way of inserting transgenes into plants cells as follows: (6)

Answer 21

1. The Ti plasmid is removed from the bacterium and a restriction enzyme cuts the plasmid.
2. The enzyme ligase splices the gene of interest, the transgene, into the plasmid to form a recombinant plasmid.
3. The plasmid is introduced into a plant cell and the part with the gene becomes integrated into the cell’s chromosomal DNA.
4. Transformed plant cells are grown by tissue culture.
5. Finally they are planted out to grow normally.
6. The transgenic plants then have to be extensively tested by growing them under different environmental conditions to ensure that the transgene has no detrimental effects on other plant functions or on the quality of the product and to check the overall performance of the plants.

Question 22

World-wide geneticists are working to introduce new genes into crop plants to make them more ___.

Answer 22

productive

Question 23

What is plant tissue culture used for?

Answer 23

Plant tissue culture is widely used to produce clones of a plant in a method known as micropropagation.

Question 24

What micropropagation?

Answer 24

It is a technique used to grow lots of plants from tiny pieces from the parent plant in sterile agar jelly with plant hormones and nutrients.

Question 25

Tissue culture involves the following steps: (6)

Answer 25

1. Small amounts of parent tissue or a number of cells are taken.
2. The plant material is transferred to plates containing sterile nutrient agar jelly.
3. Plant hormones are added to stimulate the cells to divide.
4. Cells grow rapidly into small masses of tissue.
5. More growth hormones are added to stimulate the growth of roots and stems.
6. The tiny plantlets are transferred into potting trays where they develop into plants.