Application Questions And Problems

*21. A 22-kb piece of DNA has the following restriction sites.

HindIII site Hpa I site \

HindIII site

Hpa I site

A batch of this DNA is first fully digested by Hpal alone, then another batch is fully digested by HindIII alone, and finally a third batch is fully digested by both Hpal and HindIII together. The fragments resulting from each of the three digestions are placed in separate wells of an agarose gel, separated by gel electrophoresis, and stained by ethidium bromide. Draw the bands as they would appear on the gel.

A piece of DNA that is 14 kb long is cut first by EcoRI alone, then by Smal alone, and finally by both Eco RI and SmaI together. The following results are obtained.

Digestion by EcoRI alone

3-kb fragment

5-kb fragment

6-kb fragment

Digestion by SmaI alone

7-kb fragment 7-kb fragment

Digestion by both EcoRI and SmaI

2-kb fragment

3-kb fragment

4-kb fragment

5-kb fragment r

Reaction containing

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