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mutatis mutandis*
Whence blue eyes?
What’s a ‘good’ gene? Where do new ones come
from?
*According to dictionary.com: the necessary changes have been
made
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A word on words
❖
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DNA sequence: The exact series of bases in a given stretch of
DNA. Examples might be
❖
GGAGAGAGATCCTA
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CCACACGATCGATCGATC
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CTGCTGCTGAAAGAGAAA
Amino acid sequence the same, but names the amino acids in a
stretch of protein--AKA the ____________ structure of a
protein?
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Why we look different
Yup, it’s ‘genes’
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How much DNA in...
❖
basepairs?
❖
millimeters?
❖
copies of each gene?
Information flows!
http://www.csus.edu/indiv/l/loom/gene%20expr/overview.jpg
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Mutations matter
Source: damnyouautocorrect.com
Warning: frank language & annoying site
design
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Mutants among us
❖
Blue eyes stand up. Green too
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Congratulations. You’re mutants
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Seeing eyes
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Blinding you with Science
(jargon)
❖
Gene: A stretch of DNA that represents all the information for a
product as well as when and where to make the product
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Allele: A version (or flavor) of a gene; two alleles of the same gene
my differ by a nucleotide or dozens of them--generally a small
number
❖
Dominant/recessive: Two alleles enter; one allele leaves (which
version manifests in the organism)
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NOT which version is more common!
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You’ve seen this before
❖
What does it mean?
A
a
A
AA
Aa
a
Aa
aa
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Look into my eyes...
❖
or his/hers...
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Terminology & eyes
What does it mean genetically when we say ‘brown eyes
are dominant’?
Why should that be so? What do brown alleles got that
blue do not?
Getting at the source
❖
Blue-eyed people have the same amino-acid specifying
sequence for pigment production as brown-eyed.
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Humans have only one primary pigment production
pathway that makes melanin, this colors hair, skin, eyes
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In other words: the same pathway ‘browns’ eyes & skin
❖
Are blue-eyed people albinos?
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Possibilities, please
If it’s not in the coding sequence, then...
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How did blue-eyed
freaks of nature arise?
does it keep
happening?!?
Plagiarism?
❖
Assignment: what are the colors of the rainbow
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Finding: All 4 members of Team Awesome mis-spelled a
word!
❖
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Sam: Violet-Blue-Griin-Yellow-Orange-Red
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Sally: Violet-Blue-Green-Yallow-Orange-Red
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Sarah: Violet-Bloo-Green-Yellow-Orange-Red
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Solomon: Violet-Blue-Green-Yellow-Oringe-Red
Did they plagiarize? What is the basis of your conclusion?
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Provoking your thoughts
❖
Blue eyes arise from a DNA change that decreases creation of
melanin in the eye specifically
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Mutation appears identical in
single origin
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On green eyes --they are dominant to blue
all blue-eyed folks, suggesting
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Why are y’all still here?
❖
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Mutation is a good thing? Apparently blue eyes are
worthwhile
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why might this be given that blue eyes increase risk of
cataracts?*
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*Transactions of the American Ophthalmological Society 98:109-117 (2000)
Dominant & recessive, revisited
Raising Bruce’s blood
pressure
❖
Question: How is a change in DNA sequence that happened
thousands of years ago similar to a mutation?
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How is it different?
Blue eye color in humans may be caused by a perfectly
associated founder mutation in a regulatory element located
within the HERC2 gene inhibiting OCA2 expression
Hans Eiberg · Jesper Troelsen · Mette Nielsen ·
Annemette Mikkelsen · Jonas Mengel-From ·
Klaus W. Kjaer · Lars Hansen
Human Genetics (2008) 123:177-87
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Why are you still here?
If blu
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Of mice & men
Variety is the spice of mice
Moving to the beach
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mouse pigmentation is coding sequence
Fig. 25-4
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