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SingaporeBiotechnology

Genetic Engineering Techniques

5 dot points across 5 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

How do we read the exact order of bases in DNA, and how does that give each person a unique genetic fingerprint?

Describe the purpose of DNA sequencing and how genetic profiling produces a pattern unique to an individual
A focused answer to the O-Level outcome on sequencing and profiling. What sequencing reads, how genetic profiles use variable regions, and the uses in forensics and relationships.
8 min answer →

How can we separate a mixture of DNA pieces by size and read the result as a pattern of bands?

Describe gel electrophoresis and explain how it separates DNA fragments by size
A focused answer to the O-Level outcome on gel electrophoresis. Loading DNA into a gel, applying an electric field, why smaller fragments travel further, and reading the bands.
9 min answer →

Once a gene is inside a plasmid, how do you get bacteria to take it up and make millions of copies?

Describe how host cells are transformed with recombinant DNA and how transformed cells are identified and grown
A focused answer to the O-Level outcome on transformation and cloning. Getting recombinant plasmids into bacteria, using marker genes to select them, and growing them to express the gene.
9 min answer →

How do scientists cut DNA at exactly the right place and then glue pieces back together?

Describe the action of restriction enzymes and DNA ligase and explain how they are used to make recombinant DNA
A focused answer to the O-Level outcome on cutting and joining DNA. Restriction enzymes and recognition sites, sticky ends, the role of DNA ligase, and making recombinant DNA.
9 min answer →

Starting from a tiny trace of DNA, how can we make millions of copies in a few hours?

Describe the polymerase chain reaction and explain how it amplifies a specific DNA sequence
A focused answer to the O-Level outcome on PCR. The three temperature steps, the role of primers and a heat-stable polymerase, the doubling per cycle, and what PCR is used for.
9 min answer →