Gene Technologies

Question 1

Obtaining DNA samples

Answer 1

Using reverse transcriptase (derived from viruses)
Remove mRNA from a cell
Add reverse transcriptase
Converts RNA into double stranded DNA

Obtain a sample of DNA from a cell
Use restriction endonucleases to cut out required gene

Use a gene machine
Determine the amino acid sequence of the protein
Look up the mRNA codons
Identify the complementary DNA triplets
Enter DNA ode into a computer
In an automated process nucleotides are assembled in the correct order to make a gene DNA polymerase used to join nucleotides

Question 2

PCR

Answer 2

In vitro DNA replication
DNA heated to 95°C
Hydrogen bonds break and strands separate
Cooled to 55°C
Primers bind/anneal to DNA
Heated to 72oC
Complementary nucleotides attach
DNA polymerase (heat stable) joins nucleotides together
Cycle repeated

Question 3

In vivo

Answer 3

Attached DNA fragment to a plasmid (vector) from bacteria
Plasmid returned to bacterial cell
Plasmid is replicated during binary fission

Question 4

Genetic modification

Answer 4

Obtain DNA coding for the desired gene using a restriction endonuclease
Use same restriction endonuclease enzyme to cut open a plasmid with sticky ends Sticky ends/unpaired bases make process easier
Use DNA ligase to join desired gene to plasmid
Return plasmid to (bacterial) cell
Use of Ca2+ / electric shock;

Question 5

Marker genes

Answer 5

Used to identify whether a bacterial cell/plasmid has been modified.
Desired gene is inserted into marker gene eg conferring antibiotic resistance
Cells that are no longer resistant to antibiotic have taken up the new gene

Question 6

Gene probe

Answer 6

A short section of DNA with fluorescence or radioactivity attached
DNA probe is complementary to the target gene
Probe hydrogen bonds to complementary DNA and can be detected.

Question 7

Gene therapy

Answer 7

Used to treat genetic disease
Copies of corrected gene inserted into somatic cells
Using a harmless virus or liposome

Question 8

Genetic fingerprinting

Answer 8

Used to distinguish between individuals using only DNA
DNA released from cells
DNA cut into fragments using restriction endonuclease to form restriction fragments
DNA fragments separated using gel electrophoresis
DNA moves to the positive electrode
Short sections of DNA move further than longer sections.
DNA is detected using dye or DNA probes