Question

Assume that a plasmid is 4000 base pairs in length and has restriction sites at the following locations: 600, 1000, 2200, and 3800. Give the expected sizes of the restriction fragments following complete digestion.

Answer 1

The expected restriction fragment sizes after complete digestion of a 4000 base pairs plasmid with restriction sites at 600, 1000, 2200, and 3800 would be 400 bp, 1200 bp, 1600 bp, and 800 bp.

Step-by-step explanation:

If a plasmid is 4000 base pairs in length and has restriction sites at 600, 1000, 2200, and 3800, we can calculate the expected sizes of the restriction fragments following complete digestion. To get the lengths of the individual fragments, we subtract the position of each restriction site from the position of the next one:

• Fragment 1: 1000 - 600 = 400 bp
• Fragment 2: 2200 - 1000 = 1200 bp
• Fragment 3: 3800 - 2200 = 1600 bp
• Since the plasmid is circular, we also count the fragment from the last restriction site to the first one, going around the circle:
• Fragment 4: 4000 (end of the plasmid) + 600 (start of the plasmid) - 3800 = 800 bp

The expected fragment sizes following complete digestion would therefore be 400 bp, 1200 bp, 1600 bp, and 800 bp.