Describe key biotechnology techniques and evaluate their applications and implications

What this dot point is asking

SCSA wants you to know how the core techniques work, what they are used for, and to evaluate the implications. A strong answer pairs each technique with a clear purpose and weighs benefits against risks rather than only listing methods.

Restriction enzymes and recombinant DNA

Restriction enzymes (restriction endonucleases) are bacterial enzymes that cut DNA at specific base sequences called recognition sites. Many cut in a staggered way, leaving short single-stranded overhangs called sticky ends.

Recombinant DNA is DNA combined from two different sources. To make it:

• A restriction enzyme cuts both the target gene and a vector (often a plasmid) using the same enzyme, so the sticky ends are complementary.
• The fragments are mixed and the enzyme DNA ligase joins the gene into the vector by sealing the sugar to phosphate backbone.
• The recombinant vector is inserted into a host cell (such as a bacterium), which expresses the gene.

This is how human insulin is produced: the insulin gene is inserted into bacteria that then manufacture human insulin in large quantities.

PCR (polymerase chain reaction)

PCR makes millions of copies of a target DNA sequence in vitro. It uses repeated cycles of three temperature steps:

• Denaturation (about 95 degrees Celsius): heat separates the double strand into single strands by breaking hydrogen bonds.
• Annealing (about 50 to 60 degrees Celsius): short primers bind to the ends of the target sequence.
• Extension (about 72 degrees Celsius): a heat-stable DNA polymerase (such as Taq polymerase) adds nucleotides to build new complementary strands.

Each cycle doubles the amount of target DNA, so the quantity grows exponentially. PCR is used to amplify small or degraded samples for forensics, diagnosis and research.

Gel electrophoresis

Gel electrophoresis separates DNA fragments by size. DNA is loaded into wells in an agarose gel and an electric current is applied. Because DNA is negatively charged (due to its phosphate groups), it moves towards the positive electrode. Smaller fragments move faster and travel further; larger fragments lag behind. The result is a pattern of bands that can be compared between samples.

This is the basis of DNA profiling: individuals have different lengths of repeated sequences, so their banding patterns differ, allowing identification in forensics and paternity testing.

Transgenic organisms and GM technology

A transgenic organism contains a gene from a different species, introduced using recombinant DNA techniques. Examples include:

• Bt cotton and Bt corn, carrying a bacterial gene that produces an insecticidal protein.
• Golden rice, engineered to produce beta-carotene (a vitamin A precursor).
• Bacteria and yeast engineered to produce medicines such as insulin and growth hormone.

Cloning

Cloning produces genetically identical copies.

• Reproductive cloning (such as somatic cell nuclear transfer, the method behind Dolly the sheep) places the nucleus of a body cell into an egg with its nucleus removed, creating an organism genetically identical to the nucleus donor.
• Therapeutic cloning produces stem cells for treating disease rather than a whole organism.
• Plant tissue culture clones plants from a small sample of cells, producing many identical plants.

Implications: benefits and concerns

You are expected to evaluate, not just describe.

Benefits include cheaper and more reliable medicines, crops with higher yield or pest resistance, faster disease diagnosis, and powerful forensic identification.

Concerns include:

• Ecological: transgenes spreading to wild relatives, loss of biodiversity, and pests evolving resistance to engineered crops.
• Ethical: the morality of altering organisms, animal welfare in cloning, and access to genetic information.
• Social and economic: patenting of organisms and genes, unequal access between rich and poor nations, and consumer choice about GM foods.