chapter 15

Question 1

restriction enzyme

Answer 1

Recognizes a specific DNA sequence and cuts both strands of the sugar-phosphate backbone of DNA (most of the time the cut and recognition sites are the same, though not always. Recognizes its own methylated DNA, and will not cut it

Question 2

sticky ends

Answer 2

cohesive ends with a single-stranded overhanging segments at the end of each fragment

Question 3

restriction map

Answer 3

a map of known restriction enzyme recognition sites along a sequence of DNA. Double digestion with ApaI and XhoI can distinguish the order of the restriction sites

Question 4

What are three ways that researchers try to reduce self-ligation when creating a recombinant vector

Answer 4

1. Remove the 5’ phosphate group from vector DNA so that it cannot ligate to itsel
2. Double digests
3. Blunt end cloning when complementary restriction enzymes are not available

Question 5

purpose of introducing a selective marker or plating a bacteria on a selective medium when transforming recombinant DNA in bacteria

Answer 5

only cells with the resistance marker survive, allowing researchers to identify and isolate bacteria that carry the recombinant plasmid

Question 6

Commercially-produced insulin

Answer 6

made in E.coli, separate the insulin chains from everthing else, then mix them together under correct conditions to make active insulin

Question 7

Ti-plasmid

Answer 7

most widely used method of generating transgenic plants

Question 8

Ti-plasmid has 5 regions

Answer 8

1. ori – allows the Ti plasmid to replicate independently
2. Virulence region – genes required for efficient DNA transfer
3. Genes for conjugative transfer
4. Genes for opine catabolism (for utilization of amino acids)
5. T region: combines illegitimately with the plant nuclear genome