8.4 Gene technology

Question 1

What is meant by recombinant DNA technology?

Answer 1

The transfer of DNA fragments from one organism to another

Question 2

Why does recombinant DNA technology work?

Answer 2

Because the genetic code is universal, and therefore transcription and translation occur by the same mechanism and result in the same amino acid sequence across organisms

Question 3

Summarise the process of using reverse transcriptase to produce DNA fragments

Answer 3

mRNA complementary to the target gene is used as a template. It is mixed with free nucleotides which match up to their base pairs, and reverse transcriptase which forms the sugar-phosphate backbone, to create cDNA (complementary DNA)

Question 4

Summarise the process of using enzymes to produce DNA fragments

Answer 4

Restriction endonucleases (RE) cut DNA at specific sequences. Different Res cut at different points but one RE will always cut at the same sequence. Therefore using particular REs allows you to cut out a certain gene of interest

Question 5

In which two ways can we amplify DNA fragments?

Answer 5

• In vitro
• In vivo

Question 6

Summarise the process of inserting a DNA fragment into a vector

Answer 6

A plasmid is used as the vector, and is cut using the same restriction enzymes as the DNA, so that the ends are complementary. DNA ligase joins the fragment and plasmid together

Question 7

Summarise the process of inserting a vector into a host cell

Answer 7

Known as cell transformation. The host cells are mixed with the vectors in an ice-cold solution, then heat shocked to encourage the cells to take up the vectors. The cells can then be grown and the DNA fragment will be cloned

Question 8

Summarise the process of identifying transformed cells

Answer 8

Marker genes e.g. coding for fluorescence can also be inserted into vectors along with the DNA. When cells begin to grow, UV light can be used to identify which cells have taken up the vector and which haven’t