NY-NJ Chapter LogoNewsletter
Summer 2002

In This Issue

From the Editors

From the Chair

Kudos for Chapter Members

Web Watch

Brave New World

In the Literature

Technology Review

RML Update

To The Editors

2003 Philadelphia Meeting

Special Report: MLA Benchmarking Task Force
Focus Groups

Advocacy Report

News and Announcements

Online Newsletter Index

The Newsletter is published for the members of the New York-New Jersey Chapter of the Medical Library Association.

Editor of this issue:

William Self, The Medical Library Center of New York, 5 East 102nd St., 7th Floor, New York, NY 10029 S-1, Phone: 212-427-1630, Fax: 212-860-3496, E-mail: wself@mlcny.org.


Site maintained by Webmaster: Robert Dempsey
Posted 7/25/2002
©2002 NY-NJ Chapter of the Medical Library Association
Brave New World
Alphabet Soup:
DNA, RNA, mRNA, cDNA and More

by Kristine M. Alpi, AHIP
Weill Cornell Medical Library
kalpi@att.net

Are DNA, RNA and its variants a confusing jumble of biobabble for you? Francis Crick makes it simple: "DNA makes RNA, RNA makes protein, and proteins make us." This central dogma of molecular biology can also be represented as

DNA --> RNA --> Amino Acids --> Proteins

Go to Access Excellence at http://www.accessexcellence.org/AB/GG/central.html to see a graphic representation of this process. Definitions for most of the terms that follow can be found in the NHGRI Glossary of Genetic Terms at http://www.genome.gov/glossary.cfm.

Here are the players in this chain of events:

  • DNA (deoxyribonucleic acid) is the chemical inside the cell nucleus that carries genetic instructions
  • RNA (ribonucleic acid) delivers DNA's genetic message to the part of a cell where proteins are made. There are many subtypes of RNA:

    • mRNA (messenger RNA) is the template from which new DNA is made--the deliverer of the genetic message
    • snRNA (small nuclear RNA) helps splice the mRNA to create the template
    • rRNA (ribosomal RNA) participates in making the protein, as does
    • tRNA (transfer RNA)

Why be familiar with these variations? In Entrez Nucleotides, you can limit the search to regular DNA or RNA ("genomic DNA/RNA"), mRNA or rRNA using the Molecule pull-down limit or other types using the Properties field in Preview/Index.

What about cDNA? cDNA (complementary DNA) is DNA made by researchers from the protein-producing (coding) sections of mRNA. cDNA is more stable than mRNA for experiments and is more useful than the original DNA because the regions that do not code for proteins have been removed. If you search on the term "libraries" in PubMed, you retrieve many molecular biology articles thanks to the existence of cDNA libraries.

Resources:

cDNA Library [definition, spoken explanation and illustration]. NHGRI Glossary of Genetic Terms. [Online]. Available: http://www.genome.gov/glossary.cfm

National Center for Biotechnology Information. 2001. Genetics Review. MLA CE Course Manual: Molecular Biology Information Resources. [Online]. Available: http://www.ncbi.nlm.nih.gov/Class/MLACourse/Genetics/index.html

National Center for Biotechnology Information. 2001. Molecular Genetics: Piecing It Together. Science Primer: A Basic Introduction to the Science Underlying NCBI Resources. [Online]. Available: http://www.ncbi.nlm.nih.gov/About/primer/genetics_molecular.html

National Center for Biotechnology Information. 2001. What is a Genome? Science Primer: A Basic Introduction to the Science Underlying NCBI Resources. [Online]. Available: http://www.ncbi.nlm.nih.gov/About/primer/genetics_genome.html