Stem Cell Expression Profiling

The human genome has approximately 20,000 to 25,000 genes that are used by a cell to perform various functions. The first step in gene expression is the conversion of DNA to messenger RNA (mRNA) through a process called transcription. The mRNAs are then converted into proteins, the functional units of the cell by a process known as translation. Events during transcription such as alternative splicing, as well as the activity of proteins whose function is to regulate transcription, can alter the nature and number of distinct mRNAs expressed from a single gene, thus [Page 1071]increasing biological complexity. Further complexity is achieved by the fact that apart from the genes that code for proteins, there are subsets of RNA that do not code for protein but ...