Like prokaryotes, eukaryotic organisms do not want to express
all of their genes all of the time. Given the complexity of
multicellular eukaryotes, gene regulation in these organisms
needs to be very complex. This module provides a brief overview
of the various levels of regulation of gene expression in
eukaryotes, and takes a look at the basics of transcriptional
regulation; a detailed look at eukaryotic transcriptional
regulation is beyond the scope of this course. The Need for Gene
Regulation in Eukaryotes Eukaryotes need to regulate their genes
for different reasons than prokaryotes. In prokaryotes, gene
regulation allowed them to respond to their environment
efficiently and economically. While eukaryotes can respond to
their environment (we'll see an example of this later), the main
reason higher eukaryotes need to regulate their genes is cell
specialization. Whereas prokaryotes are (relatively speaking)
simple, unicellular organisms, multicellular eukaryotes consist
of hundreds of different cell types,