A DNA construct is an artificially constructed segment of nucleic acid which is going to be 'transplanted' into a target tissue or cell.
It often contains a DNA insert, which contains the gene sequence encoding a protein of interest. The DNA insert has been subcloned into a molecular biology vector.
A DNA construct may express wildtype protein, or prevent the expression of certain genes by expressing competitors or inhibitors. It may express mutant proteins, such as deletion mutations or missense mutations. A DNA construct is often used in molecular biology to analyze macromolecules such as proteins or RNA in more detail.
A molecular biology vector is a DNA molecule used as a vehicle to transfer foreign genetic material into another cell.
The main types of vectors are plasmids, bacteriophages and other viruses, and artificial chromosomes. Common to all engineered vectors are an origin of replication, a multicloning site, and a selectable marker.
The vector itself is generally a DNA sequence that consists of an insert (transgene) and a larger sequence that serves as the 'backbone' of the vector. The backbone will include bacterial resistance genes for growth in bacteria, and promoters for expression in the organism.
The purpose of a vector which transfers genetic information to another cell is typically to isolate, multiply, or express the insert in the target cell.
Insertion of a vector into the target cell is usually called transformation for bacterial cells, or transfection for eukaryotic cells. Insertion of a viral vector is often called transduction.