* Biotechnology (Ch 27)

Question 1

Recombinant DNA technology

Answer 1

1. Isolate desired gene from the source using a restriction enzyme
2. Use the same restriction enzyme to cut the plasmid for insertion of desired gene
   * -> Function of restriction enzyme: The same restriction enzyme is used to produce the same sticky ends in the target gene and in the plasmid so that the cleaved plasmid and the target gene can be ligated together by complementary base pairing between the unpaired bases in their sticky ends
3. Join the desired gene and cut plasmid using DNA ligase
4. Induce the recombinant plasmid into bacterial cells
5. Induce the expression of the gene that encodes the protein gene product
6. Extract and purify the gene product for later use

Question 2

Plasmid

Answer 2

• A small circular piece of DNA in bacterial cell
• Used as vector to carry the desired gene into the host cell: can be taken up by bacterial cells because of their small size

Question 3

Recombinant DNA vs animal insulin

Answer 3

• Eliminate the chance of transmission of animal pathogens
• Eliminate possible allergens from pig insulin
• Eliminate possible immune response produced by diabetic patients to lower the effect of insulin since the amino acid sequence of the insulin formed by recombinant DNA technology is the same as human

Question 4

GM plants

Answer 4

• Improve nutritional content of crops (eg. vitamin A in GM rice)
• Increase tolerance to cold, drought or salinity (increases the amount of land for farming)
• Increase crop yield (eg. extend shelf life to tomato)
• Provide resistance to pests
• Provide tolerance to herbicide

Question 5

Impacts of excessive use of pesticides

Answer 5

1. Kills non-targeted organisms
2. Affect health of farmer
3. Accumulate along the food chain
4. Evolution: proportion of pesticide-resistant pests increases, lowering effectiveness of pesticides

Question 6

Why producing insulin from GM bacteria is cheaper than extracting from animal pancreas

Answer 6

1. High grow rate of bacteria -> high product yield
2. Insulin can be produced continuously
3. Lower cost of purification of insulin

Question 7

DNA fingerprinting

Answer 7

1. Extract DNA sample from the individual
2. Use restriction enzyme to cut the sample into DNA fragments
3. Add DNA fragments into the wells near the negative pole of the gel electrophoresis tank
4. Being negatively charged, DNA fragments will migrate to the positive pole in gel electrophoresis under the effect of electric field, the DNA fragments of different lengths will be separated, the shorter DNA fragments move faster than the longer ones along the gel
5. Apply dye to make the DNA bands visible

Question 8

Applications of DNA fingerprinting

Answer 8

1 .Forensic tool
2. Parentage test
3. Screening for inherited diseases
4. Establishing composition of foods

Question 9

Analysing DNA fingerprints

Answer 9

• Half of the DNA bands of A resembles with that of B, while the other half of A resembles with that of C
  -> A is the child of B and C

Question 10

Human genome

Answer 10

The base sequence of a complete set of DNA in humans

Question 11

Human Genome Project - Goals

Answer 11

• To identify and locate all genes in the human genome
• To determine the sequences of all human genes

Question 12

HGP - Implications

Answer 12

• Helps scientists identify genes that cause genetic disorders
• Help scientists to develop diagnostic tests of genetic diseases
• Helps scientists to develop treatments for genetic diseases

Question 13

HGP - Limitations

Answer 13

• Functions of many genes and the biological processes involved in human body are still unknown
• Raises ethical, legal and social issues
  -> ownership of personal genetic information/ privacy of personal genetic information/ psychological impact on knowing personal genetic information/ public perception of individuals with genetic abnormalties