Question

EcoRI recognizes the sequence 5'-G|AATTC-3' ("|" indicates the point of cleavage). Treatment of the following oligonucleotide with EcoRI would produce two oligonucleotides with sizes of _____ double-stranded nucleotides containing _____ ends. 5'-GAAGTCGATACAGAATTCGTACCTAGC-3'

a) 10; blunt
b) 11; sticky
c) 12; sticky
d) 13; blunt

Answer 1

Treatment of the oligonucleotide with EcoRI would produce two oligonucleotides, one with 12 and another with 14 double-stranded nucleotides, both with sticky ends. The correct answer is c) 12; sticky.

Step-by-step explanation:

The oligonucleotide 5'-GAAGTCGATACAGAATTCGTACCTAGC-3' when treated with the EcoRI enzyme, which recognizes the sequence 5'-G|AATTC-3' and creates sticky ends, would produce two fragments upon cleavage. Cleavage occurs exactly at the identified EcoRI site within the sequence.

Identifying the EcoRI site within the provided oligonucleotide, we see that cleavage would occur between G and A of the GAATTC sequence, resulting in two fragments. The first fragment would extend from the start to the cleavage site, and the second would extend from the cleavage site to the end of the oligonucleotide.

The first fragment is 5'-GAAGTCGATACA-3' and the second is 5'-GAATTCGTACCTAGC-3'. Thus, the sizes of the two resulting oligonucleotides would be 12 and 14 double-stranded nucleotides, respectively. Considering the known overhang that EcoRI produces, the ends are sticky, not blunt. So, the correct answer is c) 12; sticky.