Correct option is C
Step 1: Interpret the Digestion Patterns
- Single enzyme digests:
- BamHI produces two fragments (0.5 kb and 2.5 kb), indicating one BamHI site, splitting the 3 kb plasmid into two pieces.
- HincII produces one fragment (3 kb), indicating one HincII site, but since it’s a circular plasmid, a single cut linearizes it into a single 3 kb fragment.
- EcoRI produces one fragment (3 kb), indicating one EcoRI site, similarly linearizing the plasmid.
- Double enzyme digests:
- EcoRI + BamHI produces three fragments (0.5 kb, 1 kb, 1.5 kb), summing to 3 kb, indicating that EcoRI and BamHI cut at different sites, and the plasmid is divided into three segments.
- EcoRI + HincII produces two fragments (1.3 kb, 1.7 kb), summing to 3 kb, indicating that EcoRI and HincII cuts result in two segments.
- BamHI + HincII produces three fragments (0.2 kb, 0.3 kb, 2.5 kb), summing to 3 kb, indicating that BamHI and HincII cuts also result in three segments.
Analyzing the Statements:
Option (1): "HincII and EcoRI have a single recognition site each in the plasmid."
Correct – Confirmed from single digests: Both give a single 3 kb fragment individually, indicating one cut site each.
Option (2): "HincII site is located between two BamHI sites."
Possible – Let’s look at BamHI + HincII digest:
0.2, 0.3, and 2.5 kb → The two small fragments (0.2 and 0.3 kb) suggest that HincII is between two BamHI sites, producing very short segments, which supports this arrangement.
Option (3): "The distance between EcoRI and BamHI sites is less than that between the HincII site and BamHI sites."
Incorrect Statement – Let’s analyze:
EcoRI + BamHI → 0.5 kb, 1.0 kb, 1.5 kb
→ Implies EcoRI is further from one BamHI site (1.5 kb), closer to the other (1.0 or 0.5 kb).
So distance between EcoRI and BamHI sites includes a 1.5 kb segment, i.e. quite long.HincII + BamHI → 0.2, 0.3, and 2.5 kb
→ This shows HincII is much closer to one BamHI site (only 0.2 or 0.3 kb away).
Hence, the distance between HincII and BamHI is less than that between EcoRI and BamHI.
Thus, the statement in Option (3) is incorrect, because the actual data shows the HincII-BamHI distance is shorter, not longer than the EcoRI-BamHI distance.
Option (4): "HincII is located closer to one BamHI site than the other."
Correct – Supported by 0.2 and 0.3 kb fragments in HincII + BamHI digest.
