The blue-white screen is a screening technique that allows for the detection of successful ligations

DNA ligase

In molecular biology, DNA ligase is a specific type of enzyme, a ligase, that repairs single-stranded discontinuities in double stranded DNA molecules, in simple words strands that have double-strand break . Purified DNA ligase is used in gene cloning to join DNA molecules together...

 in vector-based gene cloning

Molecular cloning

Molecular cloning refers to a set of experimental methods in molecular biology that are used to assemble recombinant DNA molecules and to direct their replication within host organisms...

. DNA

DNA

Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...

 of interest is ligated into a vector. The vector is then transformed

Transformation (genetics)

In molecular biology transformation is the genetic alteration of a cell resulting from the direct uptake, incorporation and expression of exogenous genetic material from its surroundings and taken up through the cell membrane. Transformation occurs naturally in some species of bacteria, but it can...

 into competent cell (bacteria

Bacteria

Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

). The competent cells are grown in the presence of X-gal

X-gal

X-gal is an organic compound consisting of galactose linked to a substituted indole. The compound was synthesized by Jerome Horwitz and collaborators in Detroit, MI, in 1964. The formal chemical name is often shortened to less accurate but also less cumbersome phrases such as bromochloroindoxyl...

. If the ligation was successful, the bacterial colony will be white; if not, the colony will be blue. This technique allows for the quick and easy detection of successful ligation

DNA ligase

In molecular biology, DNA ligase is a specific type of enzyme, a ligase, that repairs single-stranded discontinuities in double stranded DNA molecules, in simple words strands that have double-strand break . Purified DNA ligase is used in gene cloning to join DNA molecules together...

.
Molecular cloning

Molecular cloning

Molecular cloning refers to a set of experimental methods in molecular biology that are used to assemble recombinant DNA molecules and to direct their replication within host organisms...

 is one of the most commonly used procedures in molecular biology

Molecular biology

Molecular biology is the branch of biology that deals with the molecular basis of biological activity. This field overlaps with other areas of biology and chemistry, particularly genetics and biochemistry...

.