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Assignment
Evolution, Unit 2
Mechanisms of Evolution
A. Mutation
B. Natural Selection
C. Genetic Drift
Three of the "architects" of the evolutionary synthesis:
G. Ledyard Stebbins, Jr., George Gaylord Simpson, and Theodosius
Dobzhansky, early 1970s.
http://ucjeps.berkeley.edu/bryolab/babs/AJBarchitects.html
Mutation
Genetics Review:
1. Most of our genes provide instructions for
building proteins.
2. The shape of the protein determines how it
will function.
Genetics Review:
1. Most of our genes provide instructions for building proteins.
2. The shape of the protein determines how it will function.
3. The amount of protein produced for a gene is
about as important as the shape of the
protein.
The amount of protein produced is
critical to function…
A. The kinds of effects mutations
can have on genes:
1. Silent mutations
2. LOF mutations
e.g., convergent loss of pigment in
cave fish populations is caused by
independently derived mutations
that prevents the Oca2 gene from
producing a functional protein
(LOF mutations)
Protas et al., 2006, Nature Genetics
3. GOF mutations
e.g., sickling hemoglobin
provides immunity to
malaria parasite
One nucleotide, one
amino acid, very different
proteins
4. Some mutations simply change the amount,
timing, or location of protein produced.
Regulatory sequences and promoters
(“switches”) control timing, location, and
quantity of transcription/protein production