Application Of Genetics

Question 1

What two techniques are used when producing a DNA profile?

Answer 1

› Polymerase Chain Reaction (PCR)

› Gel Electrophoresis

Question 2

What are the stages of the PCR process?

Answer 2

› DNA strands are separated by heating the DNA to 95°C
› Cooling the DNA to around 50°C to allow the primers to bind to the DNA strands
› Heating to 70°C to allow thermally stable polymerase (Taq polymerase) to reform the sugar phosphate backbone

Question 3

What are the stages of gel electrophoresis?

Answer 3

› DNA extracted and purified
› Enzymes cut DNA into fragments
› Electrophoresis separates fragments according to size
› Radioactive probes bind to certain DNA fragments
› DNA probes are exposed on X-ray film

Question 4

What are some advantages of DNA profiling?

Answer 4

› Doesn’t require an invasive method
› Reversing wrongful convictions
› Ruling out non-matches of DNA samples

Question 5

What are some disadvantages of DNA profiling?

Answer 5

› Could be seen as a violation of privacy
› DNA profiles are held in computers vulnerable to hacking
› Access and use of the data must be carefully regulated

Question 6

What are two methods of isolating a gene?

Answer 6

› Using restriction endonuclease to cut DNA at specific sequences
› Using reverse transcriptase to produce single stranded copy DNA (cDNA) which acts as a template to produce copies of the gene

Question 7

How is a recombinant plasmid made?

Answer 7

› Plasmid cut using the same restriction endonuclease that was used to isolate the gene
› Gene is inserted and then bonded using DNA ligase

Question 8

How can it be confirmed as to whether bacteria have incorporated the gene into their plasmids?

Answer 8

› Sequence the DNA of the bacteria

› Use a marker gene (e.g. An antibiotic resistance gene to test by using antibiotics whether the genes were taken up)

Question 9

What are some arguments in favour of GM crops?

Answer 9

› Higher crop yield
› Reduction in use of pesticides
› Superior keeping qualities

Question 10

What are some arguments against GM crops?

Answer 10

› Engineered crops may transfer resistance genes to wild relatives
› Reduction in biodiversity
› Possible unknown long term health effects

Question 11

What are the main uses of genetic screening?

Answer 11

› To identify if an unaffected person carries a recessive allele
› Pre-implantation/pre-natal diagnostic testing
› Predicting adult-onset disorders such as Alzheimer’s
› Forensic and identity testing

Question 12

What is gene therapy?

Answer 12

Treating a genetic disease by replacing defective alleles in a patient with copies of a new DNA sequence