6.3.9 Genetic Engineering Techniques

Question 1

What steps must be taken before an organism is genetically modified?

Answer 1

• Identification of DNA fragment or gene
• Isolation of gene
• Multiplication of DNA fragment (PCR)
• Transfer into organism using vector (plasmids, viruses, liposomes. Electroporation encourages uptake of plasmid vectors)
• Identification of cells with new DNA fragment by using a marker, then cloned

Question 2

What do restriction endonucleases, ligases and reverse transcriptase do in genetic engineering?

Answer 2

Restriction endonucleases - Cut genes at specific base sequences

Ligase - Join the cut ends of DNA by forming phosphodiester bonds

Reverse Transcriptase - Build double stranded DNA from single stranded RNA

Question 3

What do vectors do in genetic engineering?

Answer 3

Deliver DNA fragments into the cell.

Plasmids - Transfer DNA into bacteria or yeast

Viruses - Transfer DNA into human or bacterial cells

Liposomes - Fuse with cell membranes to transfer DNA into cells

Question 4

What do markers do in genetic engineering?

Answer 4

Genes which code for identifiable substances which can be tracked

Fluorescent markers - proteins which fluoresce under light

Enzyme markers - Transform colourless substrates into fluorescent or coloured ones

Antibiotic resistant markers - Desired gene inserted instead of the gene for antibiotic resistance. If the bacteria is wiped out, a replica plating method used to isolate the successfully transformed bacteria