Question

Which of the following vector(s) is(are) used to clone a DNA fragment of size 220 kb?

• A. Bacterial artificial chromosome
• B. Yeast artificial chromosome
• C. Cosmids
• D. pUC19 plasmid

Hint:

Plasmids: up to 10 kb, Cosmids: 35–45 kb, BACs: 150–350 kb, YACs: up to 1 Mb.
Always compare insert size capacity before selecting a cloning vector.

Answer 1

The Correct Option is A, B

Step 1: Different cloning vectors have different DNA carrying capacities.
Step 2: Cosmids can carry about 35–45 kb DNA inserts, and plasmids like pUC19 carry only about 5–10 kb, so options (C) and (D) are too small for 220 kb.
Step 3: Bacterial artificial chromosomes (BACs) can carry inserts of 150–350 kb, making them suitable for 220 kb fragments (option A is correct).
Step 4: Yeast artificial chromosomes (YACs) can carry very large inserts up to 1 Mb, also suitable for 220 kb (option B is correct).
\(\therefore\) Correct vectors are (A) and (B).