Choose the correct statement.

Options

A. Presence of more than one recognition site for one enzyme ,within a vector , generate several fragments, which will complicate gene cloning.
B. Ligation of alien DNA is carried out at a restriction site present in 'ori'.
C. In pBR322 one antibiotic resistance gene helps in the selection of transformants, whereas the other helps in cloning.
D. Rop helps in identificaiton of transformed cells.

Answer

To solve the question, we need to evaluate each of the given statements and determine which one is correct. Here’s a step-by-step breakdown:

### Step 1: Analyze Statement 1
- **Statement**: "Presence of more than one recognition site for one enzyme within a vector generates several fragments, which will complicate the gene cloning picture."
- **Analysis**: This statement is true. If a vector has multiple recognition sites for a restriction enzyme, it will be cut at each site, resulting in multiple fragments. This complicates gene cloning as it makes it difficult to isolate the desired fragment.

### Step 2: Analyze Statement 2
- **Statement**: "The ligation of the alien DNA is carried out at the restriction site present in URI."
- **Analysis**: This statement is false. The ligation of foreign DNA typically occurs at the restriction sites of antibiotic resistance genes, not at the origin of replication (ORI). The ORI is responsible for replication, not for ligation.

### Step 3: Analyze Statement 3
- **Statement**: "In PBR 322, one antibiotic resistant gene helps in selection of recombinants whereas the other helps in cloning."
- **Analysis**: This statement is false. In PBR 322, one antibiotic resistance gene helps in selecting transformants (those that have taken up the plasmid), while the other gene is inactivated when foreign DNA is inserted, thus helping in the selection of recombinants.

### Step 4: Analyze Statement 4
- **Statement**: "ROP helps in identification of transformed cells."
- **Analysis**: This statement is false. ROP (Replication of Plasmid) is involved in the replication process of the plasmid and does not play a role in identifying transformed cells.

### Conclusion
After analyzing all the statements, we find that only Statement 1 is true. Therefore, the correct answer is:

**Correct Statement**: Statement 1 is true.

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