27: Biotechnology

Question 1

Explain the meaning of biotechnology.

Answer 1

Biotechnology refers to the use of organisms, biological systems or processed to produce goods or provide services.

Question 2

State the definition of genetic engineering.

Answer 2

Genetic engineering refers to the changing of the genetic make-up of an organism by direct manipulation of DNA.

Question 3

Name a commonly used vector in recombinant DNA technology.

Answer 3

A plasmid, which is a small ring of extrachromosomal DNA found naturally in bacteria.

Question 4

Outline the main steps of recombinant DNA technology.

Answer 4

1. Obtain DNA fragments containing the gene of interest.
2. Obtain vectors (eg. plasmids).
3. Cut DNA fragments and plasmids with a restriction enzyme.
4. Join DNA fragments and plasmids together using a DNA ligase.

Question 5

Explain the source of the DNA fragments in recombinant DNA technology.

Answer 5

They are obtained from donor cells, which can be any nucleated cells.

Question 6

List two purposes with examples which recombinant plasmids can serve when introduced into host cells.

Answer 6

1. Producing GMOs that possess new characteristics, eg. producing fruits that do not turn brown when they are cut.
2. Producing proteins of other species, eg. producing human insulin by bacteria.

Question 7

Explain the original purpose of restriction enzymes.

Answer 7

Restriction enzymes are part of the natural defence mechanisms of bacteria against viruses. When DNA of infecting viruses enters the bacterial cells, the restriction enzymes cut the DNA into pieces and defend the bacteria against viruses.

Question 8

Name two uses of recombinant DNA technology in the medicine industry.

Answer 8

1. Production of pharmaceutical products
2. Gene therapy

Question 9

List 5 pharmaceutical products which are produced using recombinant DNA technology and explain their uses.

Answer 9

1. Human insulin, used to treat patients with type 1 diabetes.
2. Human growth hormone, used to treat patients with growth hormone deficiency.
3. Hepatitis B vaccine, used to prevent hepatitis due to viral infection.
4. Human blood clotting factor VIII, used to treat haemophilia.
5. Human interferons, used to treat cancer.

Question 10

State the method of obtaining human insulin in the past and list 4 disadvantages of this method.

Answer 10

Insulin for injection was usually extracted from the pancreas of cattle or sheep.
Problems:
1. The extraction required a long time and was expensive.
2. Only small amounts of insulin were obtained in each extraction.
3. The insulin from cattle or sheep has an amino acid sequence slightly difference from that of human insulin. They may be rejected by the immune system.
4. If the cattle or sheep are infected by pathogens, pathogens may be passed from the cattle or sheep to the patients, resulting in a higher risk of infections.

Question 11

List 4 advantages of producing insulin using recombinant DNA technology.

Answer 11

1. Insulin can be produced in a shorter time with lower extraction cost.
2. The product yield is much higher.
3. The insulin produced is structurally the same as human insulin. It is not rejected by the immune system.
4. The insulin produced is pure and the risk of causing infections is low.

Question 12

Name 3 uses of recombinant DNA technology in the agricultural industry.

Answer 12

1. Increasing the productivity of foods
2. Improving the nutritional value of foods
3. Reducing pollution caused by agriculture (eg. by using chemical pesticides)

Question 13

List 4 examples in which recombinant DNA technology is used to increase the productivity of crops and animals.

Answer 13

1. A fast-growing GM salmon grows to a marketable size in a shorter time, increasing the productivity of fish farming.
2. A pest-resistant GM maize plant produces a pest-resistant toxin to kill certain pests, reducing crop loss due to the pests.
3. A virus-resistant GM papaya plant can help reduce crop loss due to viral infection.
4. A herbicide-resistant GM soya bean plant can help reduce crop loss due to the use of herbicides.

Question 14

List 2 examples in which recombinant DNA technology is used to improve the nutritional value of foods.

Answer 14

1. Golden rice is a GM rice of which the grains are rich in β-carotene, which can be converted to vitamin A in our body, strengthening vision and immunity.
2. Pigs can be genetically modified to increase the levels of unsaturated fatty acids. Eating their meat may help prevent heart disease.

Question 15

Explain the meaning of selective breeding.

Answer 15

Selective breeding is done by selecting the plants or animals having the desirable characteristic to breed for many generations.

Question 16

State the definition of gene pool.

Answer 16

Gene pool is the total of all the alleles of all the genes in a population at a given time.

Question 17

Explain why selective breeding reduces the range of alleles in the gene pool.

Answer 17

In selective breeding, the alleles for the desirable characteristic become more and more widespread in the population. The alleles for the undesirable characteristic may be eliminated in a population eventually.

Question 18

List 3 advantages of recombinant DNA technology to produce crops or farm animals instead of using selective breeding.

Answer 18

1. Recombinant DNA technology is a quicker method.
2. Only one or several genes are involved at the same time. The results are more predictable.
3. Recombinant DNA technology can be used to transfer genes between unrelated species.

Question 19

List and explain 4 examples in which recombinant DNA technology is used industrially.

Answer 19

Enzymes for industrial use can be produced using recombinant DNA technology. Genes for the enzymes are introduced into bacteria, allowing larger amounts of enzymes to be produced by the bacteria in a shorter time and at a lower cost.
Examples:
1. Digestive enzymes in biological washing powders
2. Proteases in meat tenderisers
3. Enzymes used in cheese production
4. Enzymes used in beer production

Question 20

List and explain an example in which recombinant DNA technology is used for environmental protection.

Answer 20

Oil-eating bacteria can help clean up oil spills. They work by breaking down hydrocarbons in the oil into harmless substances. Using recombinant DNA technology, these bacteria can be genetically modified so that they break down a wider range of hydrocarbons.

Question 21

Outline the major steps of DNA fingerprinting (by restriction fragment length polymorphism analysis).

Answer 21

1. DNA is extracted from the sample of tissues collected.
2. DNA fragments containing the selected regions from the DNA sample (eg. highly variable regions) are obtained by cutting the DNA with restriction enzymes and amplifying (eg. using PCR).
3. The DNA fragments are separated according to their lengths using gel electrophoresis.
4. The pattern of bands obtained is called a DNA fingerprint, which is unique to each individual except identical twins.

Question 22

State the tissues which can be used for DNA extraction and list 3 examples.

Answer 22

Any tissue of a person can be used because they contain the same DNA. Common examples are blood, semen, and hairs.

Question 23

Explain the working principle of gel electrophoresis.

Answer 23

Gel electrophoresis makes use of an electric field to drive DNA fragments across a gel slab. DNA fragments are negatively charged during to the presence of phosphate groups. Under an electric field, they migrate towards the positive terminal. There are pores in the gel slab which allow shorter DNA fragments to move faster than the longer ones. In a fixed period of time, shorter fragments can travel further, separating DNA fragments according to their size.

Question 24

Explain the need of staining in gel electrophoresis (for direct observation of DNA fragments in the gel slab).

Answer 24

The DNA bands produced in the gel slab are invisible. Staining is required before the bands can be seen. It is commonly done using a fluorescent dye and the pattern of bands on the cell slab can be viewed under ultraviolet light.

Question 25

List an advantage of DNA fingerprinting.

Answer 25

The DNA fingerprint is **unqiue to each individual**, except for identical twins. It is a very reliable method to identify an individual.

Question 26

List 7 applications of DNA fingerprinting.

Answer 26

Forensic science, parentage tests, victim identification, authentication of foods and Chinese medicine, protection of endangered animals, tracking the source of infectious diseases, screening for genetic diseases

Question 27

Explain how DNA fingerprinting can be used to establish family relationships in parentage tests.

Answer 27

It is based on the fact that half of the genetic material of an individual comes from the father and the other half from the mother. Therefore, half the bands in the DNA fingerprint of an individual can be found in the DNA fingerprint of the father, and the remaining half can be found in the DNA fingerprint of the mother.

Question 28

Explain how DNA fingerprinting can be used in victim identification.

Answer 28

Identification can be done by comparing the DNA fingerprint of the dead body with that of the suspected victim, by obtaining DNA samples from the personal items of the suspected victims or their family members.

Question 29

Explain how DNA fingerprinting can be used in authentication of foods and Chinese medicines.

Answer 29

Authentication of Chinese medicine can be done by comparing the DNA fingerprint of an unknown sample with that of the genuine medicine. The composition of foods can also be tested by DNA fingerprinting, by producing a DNA fingerprint of a meat product and comparing the band pattern with those of different types of meat identifies the types of meat present in the meat product.

Question 30

Explain how DNA fingerprinting can be used in conservation of endangered elephants.

Answer 30

**Elephant dung** at different locations across Africa are collected and DNA fingerprints for elephants from different populations are produced. Then, DNA fingerprinting can be used to identify the **origin of ivory products** and find out the country in which the elephants were killed by comparing DNA fingerprints of the product with the DNA fingerprints of elephant dung. This helps authorities arrest illegal hunters.

Question 31

Explain how DNA fingerprinting can be used to study the parentage of wild animals.

Answer 31

DNA fingerprinting can be used to ensure **unrelated animals** are used in breeding programmes of endangered species. This increases the genetic variations between individuals in the population, increasing the chance of survival of the species.

Question 32

Explain how DNA fingerprinting can be used in tracking the source of infectious diseases.

Answer 32

DNA fingerprinting can be used to identify the strains of bacteria causing infectious diseases quickly, allowing preventive measures to be taken.

Question 33

List 6 diseases which can be screened using DNA fingerprinting.

Answer 33

Cystic fibrosis, haemophilia, Huntington's disease, Alzheimer's disease, sickle-cell anaemia, thalassemia.

Question 34

Describe how DNA fingerprinting can be used to test for sickle-cell anaemia.

Answer 34

Copies of DNA fragments containing the gene associated with sickle-cell anaemia can be obtained by PCR and cut using a specific **restriction enzyme**. Due to mutation, the diseased allele has a single base difference from the normal allele. This leads to a **loss of restriction site** in the DNA fragment containing the diseased allele. As a result, different patterns of bands appear after the DNA fragments are separated using gel electrophoresis.

Question 35

State the definition of genome.

Answer 35

A genome is the base sequence of the complete set of DNA.

Question 36

List 5 goals of the human genome project.

Answer 36

1. To determine the base sequence that makes up the human genome. 2. To locate all genes (**gene mapping**) in the human genome 3. To store the information in a database which is open to the public 4. To develop related new technologies and improve tools for data analysis. 5. To address the ethical, legal, and social issues that may arise.

Question 37

Outline a timeline for the human genome project.

Answer 37

1990: HGP started in the US, involving scientists from 18 countries. The first gene for breast cancer is mapped. 1996: Sequencing of year genome completed, mapping of mouse genome completed. 1999: Sequencing of first human chromosome completed. 2000: Draft version of human genome sequence completed, sequencing of fruit fly genome completed. 2003: Finished version of human genome sequence completed, all goals of the HGP are achieved.

Question 38

List 2 limitations of the HGP.

Answer 38

1. The functions of many genes are **still unknown** although the base sequences and locations have been found. 2. The data obtained are still **not enough to understand some biological processes**.

Question 39

List 3 benefits of the HGP.

Answer 39

1. Better understanding of genetics 2. Improved diagnoses and treatment of diseases 3. Better understanding of evolution