Genetics Toolbox 1

Question 1

What are restriction enzymes?

Answer 1

Cuts genomic DNA into restriction fragments
Each binds to a specific sequence of DNA
Also known as endonuclease

Question 2

What is recombinant DNA?

Answer 2

a combination of DNA molecules that aren’t found together in nature

Question 3

Describe the steps of PCR:

Answer 3

Heat DNA to 95ºC to separate strands and use DNA helicase
At 72ºC or cooler the bases pair up via DNA ligase annealing complementary base pairs
DNA polymerase is denatured at 95ºC so thermostable tap polymerase is used

Question 4

What are the limitations of PCR?

Answer 4

Information about the sequence of the target DNA must be known
Contamination - non-specific DNA strands can be easily amplified
Negative controls needed
Primer optimisation

Question 5

What is a vector?

Answer 5

DNA carrier molecules that transfer and replicate inserted DNA fragments

Question 6

What are the characteristics of vectors?

Answer 6

Independently replicate
Contain recognition sequences to allow insertion of fragments
Carry a selectable marker
Easily recoverable from host cell

Question 7

Describe an overview of rDNA

Answer 7

DNA to be cloned is purified
Gene isolated from DNA via PCR or restriction enzymes
Fragments produced are joined to vectors forming a recombinant DNA molecule
rDNA molecule transferred to a host cell
As host cells replicate, rDNA molecules are passed on to offspring creating a transgenic population
Cloned DNA can the recovered from host cells, purified and analysed
Encoded gene product is isolated

Question 8

What are some applications of rDNA?

Answer 8

To produce rare and expensive materials more cheaply
Experimental tool to study biological systems
Biotechnology in agriculture