Question

___A_____ and ___B___ were commonly used as vectors in the Human Genome Project (HGP).

• A. A: YAC, B: T-DNA
• B. A: YAC, B: Plasmid
• C. A: YAC, B: BAC
• D. A: BAC, B: Lambda phage

Answer 1

The correct option is C A: YAC, B: BAC

Human Genome Project (HGP) aimed at sequencing the entire human genome.

DNA from the cell is isolated and cut into fragments of smaller size. This is done as it is very difficult to sequence the long DNA molecule. These fragments are then cloned in hosts using the vectors.

The hosts commonly used in the sequencing of DNA were bacteria and yeast, and the vectors used were bacterial artificial chromosome (BAC) and yeast artificial chromosome (YAC).

YAC is used to clone very large DNA fragments. It has a very high insert capacity (200–2000 kb).

BAC is obtained from bacteria, a prokaryote. It has an insert capacity of 150–350 kb.

Tumour inducing plasmid (Ti plasmid) is present in Agrobacterium tumefaciens which is a pathogen of several dicot plants. This bacterium naturally delivers its “T-DNA” (part of Ti plasmid) to the host. This leads to transformation of normal plant cells into tumour cells. The Ti plasmid has now been modified into a cloning vector which is no more pathogenic to the plants but is still able to deliver genes of our interest into a variety of plants.

Lambda phage is a virus that infects bacteria. It is widely used as a cloning vector.