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Gene Regulation
What is it?
O Gene regulation is the process of turning
genes on and off. During early development,
cells begin to take on specific functions.
O Gene regulation ensures that the
appropriate genes are expressed at the
proper times.
Used for: Cell Differentiation
O Every cell in the human body contains a
complete copy of that person's DNA, with
tens of thousands of potentially viable
genes.
O All of these genes cannot be expressed at
once, so cells must decide which genes to
turn on and which genes to turn off.
O Ex. a skin cell turns on the genes that make
it a skin cell, while a bone cell would leave
these genes turned off.
Used for: Cell Function
O As a cell moves through its life, it has
different needs and functions, which can be
addressed with the use of this process to
determine which genes are expressed and
when.
O Likewise, cells can adapt to environmental
changes, such as an injury which requires
repair by activating new genes.
Used for: Response to
environment
O Gene regulation helps a cell respond to its
environment.
O Ex. Unicellular organisms must be able to adapt
genetic material quickly to adjust to changing
circumstances and new environments, since the
failure to do so will cause not only death of the
cell, but death of the organism itself.
O Gene regulation allows such organisms to do
things that will allow them to fit into hostile and
extreme environments and to adapt to changes.
(antibiotics)
How does it occur?
O For the cell, gene regulation can be
accomplished in a number of different ways,
with one of the most common simply being
regulation of the rate at which RNA
transcription occurs.
(Remember transcription? DNA  mRNA
when RNA polymerase attaches to the DNA
strand to make the new mRNA strand.)
Factors in transcription: because
it doesn’t happen all the time
O Operon – the “switch” to turn on/off
transcription
O Promoter – DNA site that promotes RNA
polymerase to bind (The Little Caesar’s Pizza
guy on the corner)
O Repressor – molecule that binds to DNA to
block (repress) transcription
O Inducer – molecule that takes repressor
away to RNA polymerase can continue
O Inducer (not shown) would take that active
repressor away from the operator, allowing RNA
polymerase to continue transcription.
Other methods of gene
regulation?
O We discussed transcription as one, most
common, method.
O Another is when sections of the DNA or RNA
strand are removed (introns) and what is left
(exons) are spliced together.
Methods of gene regulation
cont.
O Another is by changing the structure of DNA
(tightly wound coil vs. loosely wound coil) so
genes are deactivated
O Yet another is a different amount of RNA or
protein enzymes.