Question

A 10 kb linear DNA molecule was digested with restriction enzyme EcoRI (E) and two fragments were produced of sizes 6 kb and 4 kb. The restriction enzyme HaeIII (H) also produced two fragments of sizes 9 kb and 1 kb. When the two enzymes HaeIII and EcoRI were used together, three fragments were produced of sizes 1 kb, 3 kb, and 6 kb. A 4 kb long cloned genomic probe from this region hybridized to the 3 kb and 6 kb segments, but not to the 1 kb segment in a Southern/DNA blot (RFLP) analysis. Which of the following is the correct arrangement of the restriction sites on this molecule:

6kb E 3kb H 1kb

3kb E 1kb H 6kb

3kb H 6kb E 1kb

6kb H 1kb E 3kb

6kb E 1kb H 3kb

Answer 1

Answer :

Given that a 10 KbLb linear DNA molecule was digested using the enzymes EcoRI and HaeIII separately, as well as together.

When only EcoRI was used, two fragments were obtained, 6kb and 4kb.

When only HaeIII was used, two fragments of sizes 9kb and 1 kb were obtained.

When ,both were used together, three fragments were obtained: 6kb, 3kb and 1kb.

This can be possible with the following arrangement of restriction sites :

(a) 6kb E 3kb H 1kb

The results can be shown as :

Ε 1 2 3 4 5 6 b Issu to 9 10 d Both enzymes: 6 ikb '6kb 3kb Only ECORI (E) c 10 aw того 4kb 6Rb Only Hae II (H) H 10 | b c + c 0 1 kb akb

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