Question

Which of the following restriction enzyme sites would produce blunt-ended fragments? (The arrow represents the cutting site of the enzyme.) ______

A) G↓AATTC
B) CCC↓GGG
C) C↓CGG
D) A↓AGCTT
E) G↓GATCC

Answer 1

Option B (CCC↓GGG) is the restriction enzyme recognition site that would produce blunt-ended fragments when cut by the restriction enzyme HaeIII.

Step-by-step explanation:

Restriction enzymes, also known as restriction endonucleases, are enzymes that cut DNA at specific nucleotide sequences, producing either blunt-ended or sticky-ended fragments. The DNA sequences where these enzymes cut can often be palindromic sequences, meaning that the sequence of nucleotides reads the same in the 5' to 3' direction on both strands of the DNA molecule.

Within the options provided, the sequence recognized by the restriction enzyme HaeIII is B) CCC↓GGG. This enzyme produces blunt-ended fragments because it cuts the DNA straight across, leaving no overhanging nucleotides on either end. Blunt ends can be ligated to any other blunt-ended DNA fragment, making them useful for certain cloning techniques.

The other options listed (A, C, D, E) typically produce sticky ends, which have overhanging single-stranded DNA that can be used to ligate to complementary sticky ends of other DNA fragments.