Section 4 - Selective breeding and genetic engineering

Question 1

3 features useful in selective breeding?

Answer 1

Disease resistance, bigger size, produce more yield

Question 2

4 stages of selective breeding?

Answer 2

• Select stock with desired characteristics
• Breed them with each other
• Select best offspring and breed them together
• Continue process over several generations and desirable trait gets stronger. Eventually all offspring will have characteristic

Question 3

3 disadvantages of selective breeding and how?

Answer 3

• Reduces gene pool
• Inbreeding can cause health problems because more chance of inheriting defects when gene pool limited
• If new disease appears, less chance of resistance alleles present as not much variation so likely to die

Question 4

What do restriction enzymes do in genetic engineering?

Answer 4

Recognise specific sequences of DNA and cut DNA at these points, leaving sticky ends where they’ve been cut

Question 5

What do ligase enzymes do in genetic engineering?

Answer 5

Used to join two pieces of DNA together at their sticky ends.

Question 6

What are two different parts of DNA stuck together called?

Answer 6

Recombinant DNA

Question 7

What are vectors?

Answer 7

Something used to transfer DNA into a cell

Question 8

Two types of vectors and what they’re used for?

Answer 8

Plasmids - small, circular molecules of DNA that can be transferred between bacteria
Viruses - insert DNA into organisms they infect

Question 9

3 stages of genetic engineering?

Answer 9

• Desired DNA cut out with restriction enzyme. Plasmid DNA then cut open using same restriction enzyme.
• Plasmid DNA and DNA you’re inserting left with sticky ends and mixed together with ligase enzymes, joining pieces making recombinant DNA.
• Recombinant DNA inserted into other cells and these cells allowed to grow