Gene Expression, Microarrays, Identification, Annotation

Proteins are encoded by genes, and cell function is dictated by proteins. As a result, the hundreds of genes expressed in a cell decide what that cell is capable of. Furthermore, each stage in the information flow from DNA to RNA to protein presents a possible control point for the cell to self-regulate its functions by altering the number and type of proteins it produces. The process through which the instructions in our DNA are transformed into a functioning result, such as a protein, is known as gene expression. Gene expression is the process through which information from a gene is used to create a functioning gene product that allows it to make end products, such as protein or non-coding RNA, and, as a result, change phenotype. The products of non-protein-coding genes like transfer RNA (tRNA) and small nuclear RNA (snRNA) are typically proteins, but the product of non-protein-coding genes like transfer RNA (tRNA) and small nuclear RNA (snRNA) is a functional non-coding RNA. The basic dogma of molecular biology, first established by Francis Crick in 1958 and further refined in his 1970 essay, is described in the central dogma of molecular biology, which has been expanded by the subsequent discoveries of reverse transcription and RNA replication. Gene expression generates the macromolecular machinery for life in all known life forms, including eukaryotes (multicellular organisms), prokaryotes (bacteria and archaea), and viruses.

A microarray is a laboratory tool for simultaneously detecting the expression of thousands of genes. Microarrays, or DNA microarrays, are microscope slides with thousands of small dots in set places, each encoding a recognized DNA sequence or gene. Gene chips or DNA chips are two terms that are frequently used to describe these slides. The DNA molecules on each slide serve as probes for detecting gene expression, commonly known as the transcriptome or the set of messenger RNA (mRNA) transcripts expressed by a group of genes. mRNA molecules are normally obtained from both an experimental sample and a reference sample in order to undertake a microarray analysis.