Gene expression is the process through which the information contained in a gene is converted into a function. The majority of this process takes place through the transcription of RNA molecules, either those that code for proteins or those that do not code for proteins but instead serve other functions. Gene expression could then be interpreted as an "on/off switch" that regulates the timing and location of RNA and protein production, as well as a "volume control" that determines the amount of each product at any given point in time.[1]
Gene expression is a highly regulated process that changes dramatically in response to environmental factors and cell type. Many genes function to control the expression of others by producing RNA or proteins, as well as their degradation. Measuring the functional activity of a gene product or detecting a phenotype — an observable trait associated with a gene — can also be used to infer where, when, and how much a gene is expressed.[2]
Research your ancestors on MyHeritage
Regulation of gene expression
The regulation of gene expression — the ability of a gene to be expressed — is the most basic concept in genetics. The genotype is the DNA sequence itself, while the phenotype is the outcome of the interpretation of that sequence. Proteins that regulate growth and development or serve as enzymes in specific metabolic pathways are often the means by which such phenotypes are displayed.[3] There are two main types of genes: those that are "constitutive" and those that are "inducible." A constitutive gene is one whose transcription level remains generally stable, regardless of the surroundings of the cell. The expression of an inducible gene is altered in response to external stimuli or cell cycle phases. [4] Modulation of gene expression is possible at any stage, from the transcription of genomic DNA to RNA through the post-translational modification of proteins. The expression level of a gene also depends on the stability of the final gene product, whether that product is RNA or protein. Modifications in the number and nature of interactions among molecules can affect gene expression by modulating both DNA transcription and RNA translation.[5][6]
Examples of gene expression
Some basic examples of the significance of gene expression include: managing insulin expression to ensure that it serves as a signal for controlling blood sugar levels. Female mammals disable their X chromosomes so that their offspring don't get an "overdose" of the genes they carry. Eukaryotic cell cycle progression is regulated by cyclin expression levels.
Gene expression in genealogy
Family affiliation cannot be determined by examining gene expression directly. Genetic genealogy is the branch of genealogy that uses DNA testing to establish a person's lineage and the nature of their ties with other individuals. A DNA sample contains three different types of information. Only male samples include Y-chromosomal DNA (Y-DNA), which can be used to trace paternal descent. Mitochondrial DNA (mtDNA), found in both sexes, reveals maternal lineage. Finally, autosomal DNA (atDNA) provides data on paternal and maternal lineages.
Autosomal DNA shows the strongest indication of shared origins among near relatives, but this signal quickly fades, which makes it difficult to establish precise links beyond broad ethnic affinities by the time 5-7 generations have passed. As a result, autosomal DNA (atDNA) is most useful for tracing family history within the most recent five to seven generations. Both Y-DNA testing and mtDNA testing can only be used to determine family affiliation within a single female or male line. Y-DNA (and atDNA) mutate and evolve far more slowly than mtDNA. In order to trace a person's ancestry back far in time, both mitochondrial DNA (mtDNA) and Y-DNA tests are used. Haplogroups, indicators of a single and long line of descent, can be determined by analyzing both mitochondrial and Y-chromosome information.[7]
Explore more about gene expression
- The MyHeritage DNA test
- DNA Basics, Chapter 3: DNA Expression from the MyHeritage Blog
- DNA Basics, Chapter 4: A Glossary of Terms from the MyHeritage Blog
- The Science Behind MyHeritage DNA Testing, webinar with Gal Zrihen on the MyHeritage Knowledge Base
References
- ↑ P, Surat. A Guide to Understanding Gene Expression. AZoLifeSciences
- ↑ Gene Expression. Genome.gov
- ↑ Velculescu, V. E.; Zhang, L., Vogelstein, B.; Kinzler, K. W. 1995. Serial analysis of gene expression. Science, 270, 484-487.
- ↑ McAdams, H. H.; Arkin, A. 1997. Stochastic mechanisms in gene expression. Proceedings of the National Academy of Sciences, 94, 814-819.
- ↑ Tomilin, N. V. 2008. Regulation of mammalian gene expression by retroelements and non‐coding tandem repeats. Bioessays, 30, 338-348.
- ↑ Mattick, J. S.; Amaral, P. P.; Dinger, M. E.; Mercer, T. R.; Mehler, M. F. 2009. RNA regulation of epigenetic processes. Bioessays, 31, 51-59.
- ↑ Research Guides: Genetic Genealogy: DNA and Family History: Introduction