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'-CAAGTCGATACAGAATTCGTACCTAGT-3'

a) 10, 5'-CAAGT
b) 12, 5'-CAAGTCGATACA
c) 14, 5'-CAAGTCGATACAGA
d) 16, 5'-CAAGTCGATACAGAA

Answer 1

EcoRI would cut the given DNA sequence to produce two fragments: one with 12 double-stranded nucleotides ending with 5'-CAAGTCGATACA, the correct answer being option b.

Step-by-step explanation:

The enzyme EcoRI recognizes the specific DNA sequence 5'-G|AATTC-3' and cuts the DNA at the location indicated by the vertical line (|), resulting in sticky ends. In the provided oligonucleotide sequence 5'-CAAGTCGATACAGAATTCGTACCTAGT-3', EcoRI would cut the DNA between the G and AATTC, producing a sticky end with the overhanging sequence AATTC on one fragment and a complementary sticky end on the other fragment.

After cleavage, we will get two DNA fragments. The first fragment starting from the 5' end till the cleavage site would be 5'-CAAGTCGATACA. The second fragment would be from the cleavage site till the end of the oligonucleotide. Therefore, the correct answer to the student's question is option b, producing two oligonucleotide sizes of 12 double-stranded nucleotides containing 5'-CAAGTCGATACA ends.