The following sections of this BookRags Literature Study Guide is offprint from Gale's For Students Series: Presenting Analysis, Context, and Criticism on Commonly Studied Works: Introduction, Author Biography, Plot Summary, Characters, Themes, Style, Historical Context, Critical Overview, Criticism and Critical Essays, Media Adaptations, Topics for Further Study, Compare & Contrast, What Do I Read Next?, For Further Study, and Sources.
(c)1998-2002; (c)2002 by Gale. Gale is an imprint of The Gale Group, Inc., a division of Thomson Learning, Inc. Gale and Design and Thomson Learning are trademarks used herein under license.
The following sections, if they exist, are offprint from Beacham's Encyclopedia of Popular Fiction: "Social Concerns", "Thematic Overview", "Techniques", "Literary Precedents", "Key Questions", "Related Titles", "Adaptations", "Related Web Sites". (c)1994-2005, by Walton Beacham.
The following sections, if they exist, are offprint from Beacham's Guide to Literature for Young Adults: "About the Author", "Overview", "Setting", "Literary Qualities", "Social Sensitivity", "Topics for Discussion", "Ideas for Reports and Papers". (c)1994-2005, by Walton Beacham.
All other sections in this Literature Study Guide are owned and copyrighted by BookRags, Inc.
A genetic marker is an easily observed gene. When the gene is expressed, the phenotypic effects are very obvious. The gene is consequently used to identify an individual or a cell that carries it. It can also be used as a probe to mark a nucleus, chromosome or locus.
Genetic markers can include the production of various easily screened chemicals, or more obvious effects such as colors or different structures. Genetic markers can also be used as an identifier for genetic engineering. After the marker is linked to a gene, its subsequent presence in cells indicates a successful genetic transformation. Markers of this nature can include antibiotic resistance, fluorescent genes, or other characteristics that the non-transformed organism is lacking.
Genetic markers are a powerful tool. Because of speed and cost-effectiveness, they are still used as an efficient method of screening organisms and producing initial maps of the genetic material of organisms, even when many more precise molecular tools are available.