ABSTRACT
Classical molecular biology experiments were designed to quantify how much of a single type of molecule (e.g., a protein or a mRNA encoded by a gene) is present in a sample. Typical techniques for these types of experiments are Northern blotting or quantitative reverse transcription polymerase chain reaction (RTqPCR; see BioBoxes 3.1 and 3.8). The introduction of microarray technology brought about the possibility to measure very many different types of molecules of one chemical class in a single sample, e.g., all mRNA transcripts encoded in the genome. These new whole genome arrays can now be used to run experiments for hypothesis generation rather than hypothesis validation.
