Question

a restriction enzyme (endonuclease) targets dna 1000 base pairs long at the following recognition sites: 300 base pairs, 450 base pairs and 650 base pairs (see below). what is the base pair length of the second restriction fragment (300 bp to 450 bp) in this dna?
150 bp
300 bp
350 bp
200 bp
1000 bp

Explanation:

Step1: Calculate fragment length

Subtract start from end: $450 - 300 = 150$

Answer:

A. 150 bp