Gene Expression

Question 1

Explain how gel electrophoresis

Answer 1

• DNA samples loaded into wells in a porous gel and covered in buffer solution (whihc conducts electricity)
• Electrical current passed through –> DNA is negatively charged so moves to positive electrode
• Shorter DNA fragments travel faster so they travel further

Question 2

Describe the stages of in-vivo cloning

Answer 2

1) Prepare DNA fragment using restriction endonucleases (to form sticky ends)
2) Insert DNA fragment into plasmid via DNA ligase
3) Transformation: Recombinant plasmids inserted into bacteria. Requires addition of Ca2+ and heat shock, making it easier for plasmids to pass through the bacterial cell wall.
4) Identify bacteria with recombinant plasmid
5) Multiply bacteria