AQA A-Level 8.4 Gene technologies

To be continued

What is recombinant DNA technology?

Transfer of DNA fragments from one organism or species to another

Explain why transferred DNA can be translated within cells of recipient (transgenic) organisms

1. Genetic code is universal

2. Transcription and translation mechanisms are universal

Describe how DNA fragments can be produced using restriction enzymes

1. Restriction enzymes cut DNA at specific base ‘recognition sequences’ either side of the desired gene. The Shape of recognition site is complementary to active site

2. Many cut in a staggered fashion, forming ‘sticky ends’ (single stranded overhang)

Describe how DNA fragments can be produced from mRNA

1. Isolate mRNA from a cell that readily synthesises the protein coded for by the desired gene

2. Mix mRNA with DNA nucleotides and reverse transcriptase→reverse transcriptase uses mRNA as a template to synthesise a single strand of complementary DNA (cDNA)

3. DNA polymerase can form a second strand of DNA using cDNA as a template

Suggest two advantages of obtaining genes from mRNA rather than directly from the DNA removed from cells