19) Genetic Technology

Question 1

What are the properties of plasmids that allow them to be used in gene cloning ? (7)

Answer 1

• double stranded DNA
• have, restriction site / target sequence for restriction enzyme
• allows gene (for cloning) to be inserted
• small
• plasmid can, enter (host) cell / bacterium
• circular
• stable
• contain marker genes / genes for antibiotic resistance
• used to identify recombinant, (bacterial) cells
• replicate, fast / independently
• get many copies of cloned gene

Question 2

Outline the principles of genetic engineering. (6)

Answer 2

• manipulate DNA to modify organism’s characteristics.
• gene obtained using restriction enzyme.
• Reverse transcriptase makes gene using mRNA.
• gene inserted into plasmid using Ligase.
• recombinant plasmid inserted into host cell.
• cloning.

Question 3

Explain the roles of restriction endonucleases

Answer 3

• cut DNA at restriction site.
• give sticky/blunt ends.

Question 4

Explain the roles of Ligase

Answer 4

• join gene to plasmid.
• seal sugar phosphate backbone.
• make phosphodiester bonds.
• make recombinant DNA.

Question 5

Explain the roles of Reverse Transcriptase

Answer 5

• makes cDNA from mRNA.
• DNA is initially single stranded.