Expression cassette
Encyclopedia
An expression cassette is made up of one or more gene
s and the sequences controlling their expression. Three components comprise an expression cassette: a promoter sequence, an open reading frame
, and a 3' untranslated region that, in eukaryotes, usually contains a polyadenylation
site. The cassette is part of vector DNA used for cloning and transformation
. Different expression cassettes can be transformed into different organisms including bacteria, yeast, plants, and mammalian cells as long as the correct regulatory sequences are used. In each successful transformation, the expression cassette directs the cell's machinery to make RNA and protein. Some expression cassettes are designed for modular cloning of protein-encoding sequences so that the same cassette can easily be altered to make different proteins.
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
s and the sequences controlling their expression. Three components comprise an expression cassette: a promoter sequence, an open reading frame
Open reading frame
In molecular genetics, an open reading frame is a DNA sequence that does not contain a stop codon in a given reading frame.Normally, inserts which interrupt the reading frame of a subsequent region after the start codon cause frameshift mutation of the sequence and dislocate the sequences for stop...
, and a 3' untranslated region that, in eukaryotes, usually contains a polyadenylation
Polyadenylation
Polyadenylation is the addition of a poly tail to an RNA molecule. The poly tail consists of multiple adenosine monophosphates; in other words, it is a stretch of RNA that has only adenine bases. In eukaryotes, polyadenylation is part of the process that produces mature messenger RNA for translation...
site. The cassette is part of vector DNA used for cloning and transformation
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...
. Different expression cassettes can be transformed into different organisms including bacteria, yeast, plants, and mammalian cells as long as the correct regulatory sequences are used. In each successful transformation, the expression cassette directs the cell's machinery to make RNA and protein. Some expression cassettes are designed for modular cloning of protein-encoding sequences so that the same cassette can easily be altered to make different proteins.