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A restriction enzyme cutting site may be present or absent in a particular 200 kb region of human chromosome 1 - VCE - SSCE Biology - Question 18 - 2005 - Paper 1
Question 18
A restriction enzyme cutting site may be present or absent in a particular 200 kb region of human chromosome 1. chromosome 1 with cutting site cutting site chromo... show full transcript
Worked Solution & Example Answer:A restriction enzyme cutting site may be present or absent in a particular 200 kb region of human chromosome 1 - VCE - SSCE Biology - Question 18 - 2005 - Paper 1
Step 1
A person heterozygous for this cutting site would have the following gel pattern after digestion with the enzyme.
Answer
In the case of a person heterozygous for the cutting site, the enzyme will cut one chromosome at the designated site and will not cut the other. This results in distinct fragment sizes that can be visualized on a gel.
- With Cutting Site: The chromosome fragment will be cut into two pieces, approximately 75 kb and 125 kb in size.
- Without Cutting Site: The entire 200 kb fragment remains uncut.
Thus, upon analysis, the gel will display bands corresponding to:
- A band at 200 kb from the chromosome without the cutting site.
- Two bands at 75 kb and 125 kb from the chromosome with the cutting site.
The correct gel pattern representing these fragment sizes corresponds to option A.