DNA splicing, how many pieces of DNA would result from this cut? Please help.?

Question

The restriction endonuclease EcoRI recognizes the site GAATTC. It cuts the DNA molecule as follows: (where I put the slashes) /

A-T-G/A-A-T-T-C-T-C-A-A-T-T-A-C-C-T
T-A-C-T-T-A-A/G-A-G-T-T-A-A-T-G-G-A

I don't understand how to answer these questions:

1. How many pieces of DNA would result from this cut?
2. Write the base sequence of the DNA fragments on both the left and right side of the "cut."
3. DNA fragment size can be expressed as the number of base pairs in the fragment. Indicate the size of the fragments. (The smaller fragment and the longer fragment)

JazSinc · Answer

1.  Two pieces

2.
5'-ATG-3'____
3'-TACTTAA-3'

and
5'-AATTCTCAATTACCT-5'
____3'-GAGTTAATGGA-5'

I am using underscores _ for spacing because Yahoo Answers does not allow us to change fonts.
The idea here is that
o After the cut there are now two fragments
o Both fragments have "sticky ends"
o Pay attention to the 5' and 3' markings because directionality is important

3.  This is an unfair question because of the sticky ends.  Both fragments have unpaired bits.
Anyway:
o 3 bp with 4 unpaired at the sticky end
o 11 bp with 4 unpaired at the sticky end

Pamela · Answer

1.) 3 pieces 2.) A-T-G and G-A-G-T-T-A-A-T-G-G-A 3.) 3 bp and 11 bp

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DNA splicing, how many pieces of DNA would result from this cut? Please help.?

2 Answers