Genetic engineering (Molecular genetics)

Question 1

Define genetic engineering

Answer 1

• manipulation of organism’s genetic material
• involves transfer of genes frm one organism to another (usually diff species)
• done by use of vector molecule (carries gene to be transferred)
• vector molecules usually plasmids (circular DNA frm bacteria)

Question 2

Process of genetic engineering

Answer 2

1. Isolate desired gene (cut it with restriction enzymes)
2. Insert gene into vector gene
3. Insert recombinant plasmids into bacteria

Question 3

Advantages of producing insulin via genetic engineering

Answer 3

• doesn’t result in allergic reactions as insulin produced is similar to human insulin
• easier, cheaper to produce in large quantities
• lesser risk of contamination, don’t have obtain insulin from pancreases of animals (may contain disease-causing organisms)
• overcome ethical concerns of vegetarians, religious grps (don’t need to use insulin frm animals)

Question 4

Steps in genetic engineering

Answer 4

1. Isolate gene and use restriction enzyme to cut gene frm bacterial DNA, produce sticky ends
2. use same restriction enzyme to cut plasmid, produce complementary sticky ends
3. insert gene into plasmid, DNA ligase forms phosphodiester bonds between gene and plasmid
4. insert recombinant plasmid back into bacterium via heat shock
5. Plant cells: transgenic bacterium infect cells, foreign gene inserted into plant chromosome
6. Animal cells: Inject transgenic bacterium into embryo
7. For human insulin: grows transgenic bacteria (that have taken up recombinant plasmids) in fermenter under optimum conditions
8. Extract and purify human insulin protein

Question 5

Define transgenic plants

Answer 5

• induce infected plant cells to produce recombinant plants

- acquired foreign gene

Question 6

How heat/electric shock works

Answer 6

• opens up pores in cell surface membrane of bacterium

- plasmid can enter

Question 7

How transgenic bacterium is used for mass production human insulin

Answer 7

• bacteria isolated and grown
• insulin protein needs to be extracted and purified before use
• large amts of transgenic bacteria need to be cultured
• done thru use of fermenters

Question 8

How do large scale fermenters work

Answer 8

1. Nutrient broth: Contains essential nutrients for bacterial growth
2. pH controller: ensures optimum pH
3. Impeller: evenly distributes oxygen and nutrients
4. Cooling jacket: helps keep temp of broth optimum for bacterial growth and enzyme activity

Question 9

Genetic engineering (species)

Answer 9

• genes transferred between diff and same species

- e.g. transfer of pest-resistant gene frm wild wheat plants to common wheat plants (grown as crops)

Question 10

Selective breeding vs genetic engineering (species)

Answer 10

SB: closely related, same species
GE: diff species, same species

Question 11

Selective breeding vs genetic engineering (defective gene)

Answer 11

SB: possibility of defective gene being passed down
GE: eliminates risk of transferring a defective gene

Question 12

Selective breeding vs genetic engineering (speed of process)

Answer 12

SB: slow, involves several generations
GE: uses individual cells, reproduced rapidly in fermenters

Question 13

Selective breeding vs genetic engineering (efficiency)

Answer 13

SB: less efficient, organisms grow slower, require more food
GE: more efficient, transgenic organisms grow faster, require lesser food