Genetic Engineering

Question 1

What are the two main groups used in genetic engineering?

Answer 1

Restriction endonuclease enzymes

D.N.A ligase enzymes.

Question 2

What do restriction endonuclease enzymes do?

Answer 2

These enzymes cut D.N.A into fragments with unpaired sticky ends I.e a sequence of unpaired D.N.A bases.

Question 3

What was the first restriction endonuclease enzyme to be discovered and use this as an example to illustrate how this class of enzymes work.

Answer 3

The first restriction enzyme discovered is called EcoR1 which searches for the D.N.A sequence GAATTC and cuts between G and A In This sequence. The enzyme then runs down the other side of the D.N.A molecule, searching for the same sequence and cutting in the same way. The result is a large number of D.N.A fragments of different lengths with sticky ends at either end.

Question 4

What is a sticky end?

Answer 4

These are unpaired base sequences at each end of a fragment of D.N.A produced by a restriction endonuclease enzyme.

Question 5

What is the role of D.N.A ligase enzymes?

Answer 5

These join fragments of D.N.A together that have been produced by restriction endonuclease enzymes.

Question 6

What is a recombinant plasmid?

Answer 6

These are plasmids which have been opened up using a restriction endonuclease enzyme and have had a section of foreign D.N.A inserted into them using D.N.A ligase enzymes.

I.e they are plasmids containing foreign D.N.A

Question 7

How are recombinant plasmids introduced into bacteria and what does this give?

Answer 7

Bacteria have their cell walls removed and are mixed with recombinant Plasmids in solution which are taken up by the bacteria through their plasma membranes to produce recombinant bacteria.

Question 8

What is a marker gene?

Answer 8

This is a means of making the process of making recombinant bacteria more efficient by inserting a gene for some feature which can be detected by a bacterial colony that has taken up the recombinant plasmids.

Question 9

How have the processes of genetic modification been used in plants?

Answer 9

Genes have been inserted which offer herbicide resistance and also genes that allow plants to produce fish oils.

Question 10

How have the principles of genetic modification been applied to animals?

Answer 10

This technique can also be used to genetically modify animals producing transgenic animals containing genes from other species. E.g cows producing milk containing human insulin.

Question 11

What are the concerns surrounding G.M crops?

Answer 11

There are some concerns around G.M crops because the pollen can hybridise with close relatives in the natural world I.e weeds. In this way there is the possibility that these genes could spread out into many other plants.

Question 12

What was the human genome project?

Answer 12

This was an international project designed to determine:

1. ) the sequence of base pairs that make human D.N.A
2. ) the locus of all human genes on our 23 chromosomes
3. ) the function of all human genes.

Question 13

What is the most common form of gene therapy?

Answer 13

The most common form of gene therapy involves using a functional, dominant copy of a gene to mask a recessive mutant gene in the case of a genetically inherited illness.

Question 14

In gene therapy what is the therapeutic protein?

Answer 14

The protein for which the the dominant gene encodes.

Question 15

Name some genetic conditions for which gene therapy has been used to treat.

Answer 15

This technique has been successfully used to treat leukemia, haemophilia, cystic fibrosis and Parkinson’s disease.

Question 16

What are the two main types of gene therapy?

Answer 16

Somatic gene therapy.

Germline gene therapy.

Question 17

What is somatic gene therapy?

Answer 17

In this case the therapeutic genes are transferred into somatic body cells in some way e.g by using a nebuliser. In this case the effect is only seen in the patient and is not inheritable.

Question 18

What is germline gene therapy?

Answer 18

In this case gametes are modified by introducing functional genes which are integrated into the genome of the cell. The zygote, produced through fertilisation will now contain the functional gene. This is inheritable.

Question 19

What is D.N.A fingerprinting/profiling?

Answer 19

This is a means of identifying an individual organism from its D.N.A

Question 20

How does D.N.A fingerprinting work?

Answer 20

1. ) 99.9% of all human D.N.A sequences are the same in every person.
2. ) however enough D.N.A is different to distinguish one individual from another due to the existence of highly variable repeat sequences called variable number tandem repeats (VNTR’s).
3. ) loci are very similar between closely related humans. However they are so variable between unrelated people that it is almost impossible for two unrelated people to share the same VNTR’s

Question 21

What is genetic engineering?

Answer 21

the transfer of a gene from one species to another.

Question 22

What are the two main methods of animal cloning?

Answer 22

By using early animal embryos

By using nuclear transplant.

Question 23

What is a blastula?

Answer 23

A solid ball of genetically identical totipotent stem cells.

Question 24

How can cloning be achieved using early animal embryos?

Answer 24

A blastula is taken and the cells that make it up are separated using an enzyme like trypsin and are then transferred to Petri dishes containing nutrient agar. These cells sink through the agar to the bottom and create a layer called the primary culture from which secondary cultures can be made. Using the correct combination of hormones each cell can then be made into a new embryo which can then be transplanted into surrogate mothers with the potential to produce hundreds of genetically identical animals.

Question 25

How is cloning achieved using nuclear transplant?

Answer 25

To achieve this a secondary oocyte is denucleated and that nucleus is replaced with a diploid nucleus from a somatic cell of the animal intended to be cloned. This creates an artificial zygote which is stimulated to divide until it reaches a suitable stage of development, at which stage it is transplanted into a surrogate mother at the correct stage of her reproductive cycle.

Question 26

What are the two main methods of plant cloning?

Answer 26

Taking cuttings

Micropropagation.

Question 27

How can a plant clone be produced by taking a cutting?

Answer 27

A cutting is taken of the stem and are treated with hormone rooting powder and are then planted out. The plants produced are genetically identical.

Question 28

What is Micropropagation?

Answer 28

Meristematic tissue from the plant to be cloned is taken and the stem cells which make it up are separated using pectinase. The separated cells are then cultured in sterile conditions on nutrient agar. with the correct combination of plant hormones these cells can be made to grow into new plants.