Gene Technology Mechanisms
Explain how restriction endonucleases are used in genetic engineering
→ Cut DNA at specific base sequences (restriction sites)
Function of primers in PCR
→ Provide starting point for DNA synthesis
What is SCID?
→ Lack of functional T and B cells
What is a DNA probe?
→ Complementary labelled DNA sequence
Define GMO
→ Organism with altered DNA
Why are sticky ends more useful than blunt ends?
→ Complementary base pairing → easier ligation
Role of Taq polymerase
→ Heat-stable enzyme synthesising DNA
Explain role of adenosine deaminase
→ Breaks down deoxyadenosine → prevents lymphocyte toxicity
Explain RFLP
→ DNA cut → fragments separated → probe identifies sequence
Define transgenic organism
→ Contains DNA from another species
Explain role of DNA ligase
→ Forms phosphodiester bonds between DNA fragments
Why is PCR cyclic?
→ Repeated denaturation, annealing, extension → exponential amplification
Difference between somatic and germline gene therapy
→ Somatic = not inherited; germline = inherited
Explain purpose of genetic screening
→ Identify mutations / assess disease risk
Explain advantage of Bt maize
→ Produces toxin → reduces insecticide use
Explain how vectors deliver DNA into cells
→ Plasmids/viruses carry recombinant DNA into host
Explain how dideoxynucleotides allow sequencing
→ Terminate DNA chain → fragments of different lengths
Explain how retroviruses are used in gene therapy
→ Insert DNA into host genome
How do microarrays detect gene expression?
→ mRNA → cDNA → hybridises to known sequences
Explain herbicide resistance in crops
→ Survive spraying → easier weed control
Explain how marker genes identify successful transformation
→ Expression (colour/fluorescence) shows DNA uptake
Explain why shorter DNA fragments move further in gel electrophoresis
→ Less resistance through gel matrix
Explain HSCT in treating genetic disorders
→ Stem cells replaced → produce healthy blood cells
Explain difference between genetic profiling and sequencing
→ Profiling = compare patterns; sequencing = exact base order
Evaluate risks of GM organisms (2 points)
→ Gene transfer / ecological impact / resistance evolution