Consider a length of double-stranded DNA with the sequence
5' TTA GGA ATT CA A3'
3' AAT CCT TAA G T 5'
Adding EcoRI to a solution containing one copy of this double-stranded DNA produces:
A - VCE - SSCE Biology - Question 29 - 2013 - Paper 1
Question 29
Consider a length of double-stranded DNA with the sequence
5' TTA GGA ATT CA A3'
3' AAT CCT TAA G T 5'
Adding EcoRI to a solution containing one copy of this doubl... show full transcript
Worked Solution & Example Answer:Consider a length of double-stranded DNA with the sequence
5' TTA GGA ATT CA A3'
3' AAT CCT TAA G T 5'
Adding EcoRI to a solution containing one copy of this double-stranded DNA produces:
A - VCE - SSCE Biology - Question 29 - 2013 - Paper 1
Step 1
Identify the EcoRI Recognition Sequence
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Answer
EcoRI recognizes the palindromic sequence GAATTC. In the given DNA sequence:
5' TTA GGA ATT CA 3'
3' AAT CCT TAA G 5'
we can see that the recognition sequence (GAATTC) is present.
Step 2
Determine the Result of EcoRI Digestion
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Answer
When EcoRI cuts the DNA at the recognition site, it creates two DNA fragments. Each of these fragments has unpaired single-stranded 'sticky ends' because EcoRI produces overhangs upon cleavage by cutting between the G and the A on each strand.
Step 3
Count the Number of Fragments Produced
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Answer
Upon digestion, we find that the original double-stranded DNA is cleaved into two distinct fragments, and these fragments will each have sticky ends.
Step 4
Choose the Correct Answer
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Answer
Based on the analysis, the answer that best fits the result of the digestion with EcoRI is:
A. two fragments of double-stranded DNA, each with a sticky end.
