Question

Many bacteria have small circular DNA outside the genomic DNA. This extranuclear DNA

(a) Confers certain unique phenotypic characters to bacteria.
(b) Are used to monitor bacterial transformation with foreign DNA.
(c) May attach to a single mRNA and form polysome.
(d) Are also found in all eukaryotic cells.

• A. a and b
• B. b and c
• C. c and d
• D. a and d

Answer 1

The correct option is A a and b

The extranuclear small circular DNA in bacteria is known as a plasmid.

• Plasmids confer some unique phenotypic characters to bacteria such as resistance to antibiotics.
• Plasmids contain some genes known as selectable markers that can help in distinguishing transformants from non-transformants by selectively allowing the growth of transformants on a culture medium.
• For example, the gene coding for beta-galactosidase enzyme acts as a selectable marker in the screening of transformants and non-transformants by looking at the color of colonies.

Hence, only statements A and B are correct.

So, the correct answer is 'a and b'.