A primer on molecular biology for imagersV. Genomics: A global approach to the study of genes1

Abstract

Building on our discussion of DNA, RNA, and proteins ( 1 Pandit S.D. Bednarski M.D. Li K.C. A primer on molecular biology for imagers I. DNA, how does it work?. Acad Radiol. 2003; 10: 1215-1223 Abstract Full Text Full Text PDF PubMed Scopus (8) Google Scholar , 2 Pandit S.D. Li K.C. A primer on molecular biology for imagers II. Transcription and gene expression. Acad Radiol. 2004; 11: 333-334 Abstract Full Text Full Text PDF PubMed Scopus (8) Google Scholar , 3 Pandit S.D. Li K.C. A primer on molecular biology for imagers: III. Proteins: structure and function. Acad Radiol. 2004; 11: 448-461 Abstract Full Text Full Text PDF PubMed Scopus (6) Google Scholar , 4 Pandit S.D. Li K.C. A primer on molecular biology for imagers IV. Concepts and basic methods in molecular biology. Acad Radiol. 2004 Google Scholar ), this article will introduce genomics and the global approaches to understanding the molecular biology of the cell. It is worthwhile to reiterate that genes and their products do not function independently, but rather they partake in complex, interconnected pathways and networks—molecular systems—that ultimately determine the phenotype of cells, tissues, organs, and organisms. Every phenotype, normal or pathological, begins with initiating molecular events that feed into these pathways and networks that eventually determine the fate of a cell. Thus, to fully understand the molecular biology of a cell—normal or diseased—scientists must look beyond individual genes or their products to address the global cellular environment responsible for a particular phenotype. cDNA (copy DNA):a double-stranded DNA copy of an mRNA molecule synthesized by the enzyme reverse transcriptaseESTs (expressed sequenced tags):a short, partial cDNA sequence used to probe genes or gene productsKnock-out:experimental mutation or deletion of geneLinkage:the tendency for genes to be inherited together based on their physical proximity to each other on the same chromosomeOpen Reading Frame:a sequence of DNA containing a series of codons beginning with a start codon and ending with a termination codonPharmacogenomics:the area of science aimed at understanding the genomic contributions to drug responsesPhenomics:the area of science focused on understanding the molecular mechanisms behind phenotypesPhotolithography:an experimental technique that uses pulses of light to construct an oligonucleotide sequencePositional Cloning:a method using map information of a gene to obtain a clone of that geneReading Frame:a series of triplet codons in a DNA sequence. There are 3 reading frames per strand of DNA and 6 for a double-stranded DNA molecule.Recombination:a DNA rearrangement event involving the physical breakage of homologous chromosomes and exchange of their homologous DNA segmentsRFLP (Restriction Fragment Length Polymorphism):a DNA restriction fragment that is variable in size among a population due to the presence of polymorphic (variable) restriction sites in that populationSTRs (Short Tandem Repeat):synonymous to microsatellite; tandem copies of dinucleotides or trinucleotides whose copy number varies among individuals in a populationToxicogenomics:an area of science aimed at understanding the genomic contributions to adverse reactions to drugs and other chemicalsVNTRs (Variable Number Tandem Repeat):similar to STRs except VNTRs have larger (∼25 bp) repeat units a double-stranded DNA copy of an mRNA molecule synthesized by the enzyme reverse transcriptase a short, partial cDNA sequence used to probe genes or gene products experimental mutation or deletion of gene the tendency for genes to be inherited together based on their physical proximity to each other on the same chromosome a sequence of DNA containing a series of codons beginning with a start codon and ending with a termination codon the area of science aimed at understanding the genomic contributions to drug responses the area of science focused on understanding the molecular mechanisms behind phenotypes an experimental technique that uses pulses of light to construct an oligonucleotide sequence a method using map information of a gene to obtain a clone of that gene a series of triplet codons in a DNA sequence. There are 3 reading frames per strand of DNA and 6 for a double-stranded DNA molecule. a DNA rearrangement event involving the physical breakage of homologous chromosomes and exchange of their homologous DNA segments a DNA restriction fragment that is variable in size among a population due to the presence of polymorphic (variable) restriction sites in that population synonymous to microsatellite; tandem copies of dinucleotides or trinucleotides whose copy number varies among individuals in a population an area of science aimed at understanding the genomic contributions to adverse reactions to drugs and other chemicals similar to STRs except VNTRs have larger (∼25 bp) repeat units