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1mutatis mutandis*mutatis mutandis*Whence blue eyes?Whence blue eyes?
What’s a ‘good’ gene? Where do new ones What’s a ‘good’ gene? Where do new ones come from?come from?
*According to dictionary.com: the necessary changes have *According to dictionary.com: the necessary changes have been madebeen made
2
A word on words❖ DNA sequence: The exact series of bases in a given
stretch of DNA. Examples might be
❖ GGAGAGAGATCCTA
❖ CCACACGATCGATCGATC
❖ CTGCTGCTGAAAGAGAAA
❖ Amino acid sequence the same, but names the amino acids in a stretch of protein--AKA the ____________ structure of a protein?
3
Why we look Why we look differentdifferent
Yup, it’s ‘genes’Yup, it’s ‘genes’
4
How much DNA in...
❖ basepairs?
❖ millimeters?
❖ copies of each gene?
5Information flows!
http://www.csus.edu/indiv/l/loom/gene%20expr/overview.jpg
6Mutations matter
Source: damnyouautocorrect.com
Warning: frank language & annoying site design
7
Mutants among us
❖ Blue eyes stand up. Green too
❖ Congratulations. You’re mutants
8Seeing eyes
9Blinding 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
❖ 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)
❖ NOT which version is more common!
10You’ve seen this before
❖ What does it mean?
A a
A AA Aa
a Aa aa
11
Look into my eyes...
❖ or his/hers...
12Terminology & 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?
13Getting at the source
❖ Blue-eyed people have the same amino-acid specifying sequence for pigment production as brown-eyed.
❖ Humans have only one primary pigment production pathway that makes melanin, this colors hair, skin, eyes
❖ In other words: the same pathway ‘browns’ eyes & skin
❖ Are blue-eyed people albinos?
❖ Possibilities, please
If it’s not in the coding sequence, then...
14
How did blue-eyed How did blue-eyed freaks of nature freaks of nature
arise?arise?
does it keep does it keep happening?!?happening?!?
15Plagiarism?
❖ Assignment: what are the colors of the rainbow
❖ Finding: All 4 members of Team Awesome mis-spelled a word!
❖ Sam: Violet-Blue-Griin-Yellow-Orange-Red
❖ Sally: Violet-Blue-Green-Yallow-Orange-Red
❖ Sarah: Violet-Bloo-Green-Yellow-Orange-Red
❖ Solomon: Violet-Blue-Green-Yellow-Oringe-Red
❖ Did they plagiarize? What is the basis of your conclusion?
16Provoking your thoughts
❖ Blue eyes arise from a DNA change that decreases creation of melanin in the eye specifically
❖ Mutation appears identical in all blue-eyed folks, suggesting single origin
❖ On green eyes --they are dominant to blue
17
Why are y’all still here?
❖ Mutation is a good thing? Apparently blue eyes are worthwhile
❖ why might this be given that blue eyes increase risk of cataracts?*
❖ *Transactions of the American Ophthalmological Society 98:109-117 (2000)
❖ Dominant & recessive, revisited
18
Raising Bruce’s blood pressure
❖ Question: How is a change in DNA sequence that happened thousands of years ago similar to a mutation?
❖ 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
19Why are you still Why are you still
here?here?
If bluIf blu
20
Of mice & menOf mice & menVariety is the spice of miceVariety is the spice of mice
21Moving to the beach
❖ mouse pigmentation is coding sequence
Fig. 25-4
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