Biotechnology

Step 1: Understand what a suicide plasmid is.
A suicide plasmid is a type of plasmid vector that cannot replicate in a target host cell due to the absence of a functional origin of replication recognized by the host.
Step 2: Characteristics of a suicide vector.
It typically contains an antibiotic resistance marker to select for transformed cells.
It includes multiple cloning sites to insert foreign DNA.
It may have integration sites for recombination into the host genome.
However, it lacks a compatible origin of replication, which prevents it from replicating autonomously in the target host.
Step 3: Conclude the correct answer.
Since the key characteristic of a suicide vector is its inability to replicate in the host due to absence of a suitable origin of replication, option (2) is correct.

Step 1: Understand components of pBR322.
pBR322 is a widely used plasmid vector in genetic engineering. It contains: ampsuperscript{r}: Provides resistance to ampicillin (used as a selectable marker, not for amplifying enzymes).
Cla I: This is a restriction enzyme recognition site, not a gene, and doesn’t act as a selectable marker.
ori: Origin of replication, which controls the initiation of plasmid replication (not the plasmid size).
rop: Encodes a protein involved in regulating plasmid copy number, indirectly supporting replication.
Step 2: Match the correct pair.
Only rop correctly matches with “codes proteins required for plasmid replication.”