(A Level) Principles of genetic technology

Learning objectives

Define recombinant DNA, explain genetic engineering as deliberately changing an organism's DNA so that a transferred gene is expressed, and describe three ways to obtain the gene: cutting it from donor DNA, copying it from mRNA with reverse transcriptase, or synthesising it from nucleotides.

Explain how a gene is cut out and inserted using restriction endonucleases (sticky ends), DNA ligase and plasmid vectors, and the roles of reverse transcriptase and DNA polymerase in making the DNA to be transferred.

Explain why a gene moved into a new host often needs its own promoter, how marker genes for fluorescent proteins confirm that the gene is expressed, and what gene editing does by inserting, deleting or replacing DNA at chosen sites.

Describe and explain the cycles of PCR (denaturation, primer annealing, extension by heat-stable Taq polymerase) and the exponential amplification of a DNA sample.

Explain how gel electrophoresis separates DNA fragments by length, including why DNA moves towards the anode and shorter fragments move further.

Outline how microarrays are used to analyse genomes and to detect mRNA in gene-expression studies, and the benefits of databases of gene and genome sequences, protein sequences and protein structures.