Question

What is the necessity of transferring human genome to Bacterial Artificial Chromosomes (BACs), and why are BACs specifically used in Human Genome Project?

• A. BAC is the only vector that can hold the whole human genome
• B. Human genome can be cut into sizes up to 200,000 base pairs and kept in BACs
• C. Sanger’s method cannot be used on DNA fragments bigger than few thousands base pairs
• D. BACs are an integral part of the Sanger’s method of DNA sequencing
• E. BACs could be used in amplification of fragments of human genome

Answer 1

Answer: (B), (C)

Sanger’s method cannot be used on DNA fragments bigger than few thousands base pairs

Since the human genome is 3 billion base pairs in size, it was impossible to use the Sanger’s method directly. To solve the problem, the DNA was cut into millions of fragments ranging from 150 to 200 kilobase pair length. A DNA fragment of this size could only be kept in a BAC. Once stored in BAC, it could be used to amplify the number of DNA fragments for sequencing purpose.