Topic 3.5 Genetic Modification

Question 1

Gel electrophoresis

Answer 1

Gel electrophoresis is a technique that separates proteins or fragments of DNA according to size.

• Samples placed in a block of agar gel and current is applies
• Smaller samples move faster through the gel (↓resistance)

Samples will move towards the positive terminus (anode)

• DNA is negatively charged (due to phosphate group)
• Proteins are treated with an anionic detergent in order to impart uniform negative charge on all molecules.

Question 2

Gene Transfer

Answer 2

Gene transfer can occur because the genetic code in universal.

Question 3

Gene Transfer Step 1

Answer 3

DNA Extraction

• Gene of interest isolated from organism
• Gene is amplified using PCR (along with a plasmid)

Question 4

Gene Transfer Step 2

Answer 4

Digestion and Ligation

• Plasmid and gene cut with a specific restriction enzyme
• Gene is spliced into plasmid vector by DNA ligase

Question 5

Gene Transfer Step 3

Answer 5

Transformation and expression

• Recombinant plasmid is inserted into host cell
• Antibiotic selection may be used to select for successful transgenic cells (if plasmid has an antibiotic resistance gene)
• Transgenic cells express new protein (for extraction / use)

Question 6

DNA Profiling

Answer 6

DNA profiling is a technique by which individuals can be identified and compared by their genetic sequences

• Individual have different lengths of particular DNA segments called short tandem repeats (STR).
• These segments are amplified by PCR and the separated by gel electrophoresis for comparison.
• Unique profiles appear when multiple loci are compared

Question 7

Use of DNA profiling

Answer 7

• Forensic investigations (matching suspects to the crime scene)
• Paternity tests (offspring STRs are combination of parents)

Question 8

GMO Debate Benefits

Answer 8

• Could be use to improve nutritional standards
• Can grow in wide range of environments (ups yields)
• Could reduce farming costs and associated deforestation
• Can be used to reduce spoilage (longer shelf life)

Question 9

GMO Debate Risks

Answer 9

• Could trigger unexpected health issues (e.g. allergies)
• Patent protections could restrict access (equality issues)
• Possible cross-pollination with weeds (har to contain)
• Could compete with native plants (reduce biodiversity)

Question 10

Examples of GM Crop

Answer 10

• BT corn is a transgenic crop that produces an insecticide
• BT corn may be impacting survival of monarch butterflies.
• IN lab conditions with Bt pollen, however there is insufficient field evidence to support this (diet not naturally restricted)