Gene Regulation
Gene Expression and Mutation
Cells can turn genes on & off to save
energy. Not all genes will be used by all
cells all the time.
 Mutations: DNA can be mutated by

-substitution (example C for A)
-insertion (extra base added)
-deletion (base left out)
- translocation (bases from 2
chromosomes switched)
Sections of DNA
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DNA has two types of sections:
Introns: long segments of DNA that do not code
for a protein. These are switches to regulate
gene function.
Exons: segments that do code for a protein.
During transcription, introns are cut to make a
shorter mRNA strand.
Prokaryotic vs. Eukaryotic Gene
Regulation
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For bacteria (prokaryotes), the “on-off” switch
site is called an operator. Repressors bind to
the operator to turn a gene off.
For eukaryotes, transcription factors will bind to
either the promoter site (start signal) OR to the
RNA polymerase to start transcription.
Repressors and Trans. Factors