Cloning Vectors

Insertion into lacZ changes colony color in blue-white screening. This helps identify recombinants.

Plasmids are independent DNA molecules separate from the chromosome. They can replicate due to their origin.

Ori allows replication and marker helps in selection. Both are important for vector maintenance.

When insert DNA is added the vector becomes a recombinant vector. This is the main product of a cloning experiment.

During recombinant-DNA construction, the vector and insert are first prepared so that their ends can align, often by using the same restriction enzyme or compatible ends. DNA ligase then catalyses phosphodiester-bond formation between the aligned ends, creating a stable recombinant vector that carries the insert. Thus option A is correct. Pepsin is a protein-digesting enzyme active mainly in the stomach, and lipase breaks down fats; neither acts on DNA ligation. Chlorophyllase is associated with pigment metabolism in plants and has no role in joining a DNA insert to a cloning vector. The key sequence is cut, align, and ligate.

Cells with a resistance marker can grow on the related antibiotic. This allows selection of transformed cells.

Ampicillin resistance gene is a useful marker for selection. It helps identify transformed cells.

The vector is cut at a suitable restriction site to create space for the insert. Then ligase joins it.

Escherichia coli is a very common host for plasmid cloning. It grows fast and is easy to handle in the lab.

The vector carries foreign DNA into a host where copies can be made. This is the main purpose of cloning.

A cloning vector is a DNA molecule, such as a plasmid, that carries a desired DNA fragment into a host cell and helps it produce copies there. Therefore, it acts as a DNA carrier. Digestive enzymes act on food molecules such as fats; they do not deliver DNA into a host. Exam tip: Remember the key vector features—an origin of replication, a selectable marker, and a cloning site.

A unique restriction site is useful for controlled insertion. It avoids unwanted cutting at many places in the vector.

Origin of replication is needed for vector replication. Without it DNA copies will not increase in cloning.

A cloning vector needs ori selectable marker and cloning site. Chlorophyll pigment is not an essential part of a cloning vector.

A marker gene helps identify transformed or recombinant cells. It makes a cloning experiment practical.

In expression vectors promoter is needed for gene expression. In simple cloning vectors the main focus is making DNA copies.

A cloning vector is for making DNA copies. An expression vector helps gene expression and product formation.

BAC is useful for cloning large DNA fragments. At easy level remember it as a large insert vector.

YAC can be useful for carrying very large DNA inserts. Link it with yeast-based large insert vectors.

A bacteriophage is a virus that infects bacteria. Modified phage vectors can be useful in DNA cloning.

A host cell can replicate the recombinant vector. This produces many copies of the desired DNA.

A good cloning vector should have parts like ori marker and cloning site. They help in replication selection and insertion.

DNA ligase joins the foreign gene and vector ends. Restriction enzymes can create compatible ends first.

A vector carries desired DNA into a host and helps replication. Therefore a vector is necessary in gene cloning.

A selectable marker shows which cells are growing with the vector. It helps identify transformed cells.