Gene expression

Gene expression is a process in which information from a gene is used in synthesizing a functional gene product, which is often a protein. In non-protein coding genes — including ribosomal RNA, transfer RNA or small nuclear RNA genes — the product is a functional RNA.

Gene expression may be defined as the flow of genetic information from gene to protein; process or regulation of the process by which gene effects are manifested; or the manifestation of a heritable trait in the individual carrying the gene or genes that determine it.

All life forms use the process of gene expression to generate the macromolecular machinery used to sustain life.

Gene expression process

Steps in the gene expression process include transcription, RNA splicing, translation and post-translational modification of a protein. All of these steps may be modulated.

Gene expression is the most basic level at which the genotype gives rise to the phenotype. The genotype is the genetic makeup of a cell, an organism or an individual, often in reference to a specific trait or character under observation. A phenotype is the composite of the observable traits or characteristics of an organism.

There are several steps in the gene expression process that may be modulated. Those include transcription, RNA splicing, translation, and post-translational modification of a protein. Other steps include folding and protein transport.

Gene regulation is the term used for the processes cells and viruses use to regulate the how information in genes is turned into gene products.

Gene expression analysis

Gene expression analysis is the practice of determining the pattern of genes expressed at the genetic transcription level.

Techniques and technologies used in gene expression analysis include real-time quantitative reverse transcription-polymerase chain reaction (real-time qRT-PCR), in situ hybridization, microarrays and massively parallel signature sequencing.

Real-time qRT-PCR allows for reliable detection and measurement of products generated during each cycle of the polymerase chain reaction process.

The technique of in situ hybridization allows for the localization of a segment of nucleic acid within a histologic section.

Microarrays are used to determine sequence, or to detect variations in a gene sequence or expression. They are also used for gene mapping.

Massively parallel signature sequencing is used to analyze the level of gene expression in a sample.

Additional information may be found at these websites:

http://bloodjournal.hematologylibrary.org/cgi/collection/gene_expression

http://www.nlm.nih.gov/medlineplus/ency/article/003706.htm

http://www.mayoclinic.com/health/metabolism/WT00006/

http://www.nature.com/jcbfm/index.html

http://www.nutritionandmetabolism.com/

http://www.hormone.org/Public/endocrinologist.cfm

http://www.nlm.nih.gov/medlineplus/ency/article/002257.htm

http://www.ncbi.nlm.nih.gov/books/NBK22/?depth=10

http://endo.endojournals.org/

http://www.mayoclinic.org/medicalprofs/glucocorticoid-induced-diabetes.html

http://www.nlm.nih.gov/medlineplus/steroids.html

http://www.cancer.gov/cancertopics/understandingcancer/estrogenreceptors

http://www.ncbi.nlm.nih.gov/gene/2099

http://ghr.nlm.nih.gov/glossary=enzyme

http://www.nlm.nih.gov/medlineplus/ency/article/002353.htm

http://www.ncbi.nlm.nih.gov/probe/docs/applexpression/