Recombinant DNA and Plasmid Cloning

The video tutorial explains how plasmids serve as effective cloning vectors due to their ability to replicate independently within a cell. It covers the use of selectable markers, such as ampicillin resistance, to identify host cells that have taken up the plasmid. The role of restriction enzymes in incorporating foreign DNA into plasmids is discussed, along with the concept of insertional inactivation using a second marker gene. The Lac Z gene is highlighted for its function in distinguishing between recombinant and non-recombinant plasmids through a color change in the presence of xgal.

Why are plasmids considered good cloning vectors?

• They cannot be cut by restriction enzymes.

• They are always resistant to all antibiotics.

• They can replicate independently within a cell.

• They do not require a host cell to replicate.

What is the role of a selectable marker in plasmid vectors?

• To prevent plasmid replication.

• To increase the size of the plasmid.

• To identify host cells that have taken up the plasmid.

• To make the plasmid visible under a microscope.

What is the purpose of a restriction enzyme in plasmid cloning?

• To prevent the plasmid from entering the host cell.

• To cut the plasmid and foreign DNA at specific sites.

• To replicate the plasmid.

• To make the plasmid resistant to antibiotics.

What happens when a plasmid vector and foreign DNA are cut with the same restriction enzyme?

• They become resistant to all antibiotics.

• They form a new type of enzyme.

• They cannot be used for cloning.

• They can be mixed to form recombinants.

What is insertional inactivation?

• The removal of foreign DNA from the plasmid.

• The replication of plasmid without foreign DNA.

• The process of activating a second marker gene.

• The inactivation of a second marker gene when foreign DNA is inserted.

How can cells with recombinant plasmids be identified?

• By the inactivation of a second marker gene.

• By their resistance to all antibiotics.

• By their ability to grow without nutrients.

• By their increased size.

What does the Lac Z gene code for?

• A fluorescent protein.

• A restriction enzyme.

• An antibiotic resistance protein.

• The enzyme beta-galactosidase.

What color do colonies with intact vectors but no recombinant DNA turn in the presence of x-gal?

• Blue

• Red

• White

• Green

What indicates the presence of recombinant DNA in a colony?

• The colony turns blue.

• The colony turns white.

• The colony grows faster.

• The colony becomes resistant to all antibiotics.