4-6-3 Recombinant DNA Technology

Question 1

What is recombinant DNA?

Answer 1

A form of DNA that contain segments that would not normally exist together.

Question 2

What are restriction enzymes?

Answer 2

Enzymes that bind to DNA at specific sequences and cut both strands of the DNA at those specific sites, creating DNA fragments.

Question 3

What is DNA ligase?

Answer 3

An enzyme that “glue” together fragments of DNA via covalent bonding.

Question 4

How do restriction enzymes and DNA ligase work together to form recombinant DNA?

Answer 4

DNA from different sources are cut using the same restriction enzyme.

The DNA from one source joins the DNA from another source at the “sticky ends” by complementary base paring - hydrogen bonding

DNA ligase “glues” the joined sticky ends together via covalent bonding

Recombinant DNA is now formed containing DNA from different sources.

Question 5

What are vectors?

Answer 5

DNA molecules that can be joined with DNA fragments that are to be cloned. An example of a vector is a plasmid.

Question 6

What are plasmids?

Answer 6

Plasmids are small circular self-replicating DNA fragments found in bacterial cells (but NOT in the large circular bacterial chromosome). Plasmids are used as vectors in cloning.

Question 7

Brief definition of cloning

Answer 7

The production of many identical copies of a desired gene.

Question 8

Steps of cloning

Answer 8

1. DNA to be cloned is isolated and treated with a restriction enzyme.
2. Segments cut by the enzyme are linked into a recombinant DNA molecule, possibly incorporated into a vector such as a plasmid.
3. Vectors with the to-be-cloned-DNA are inserted into bacteria, where they replicate.
4. Cloned DNA can be recovered from the bacterial hosts and used for further experiments or in the production of gene products.