Transcript Document
1 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 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 different Yup, it’s ‘genes’ 4 How much DNA in... ❖ basepairs? ❖ millimeters? ❖ copies of each gene? Information flows! http://www.csus.edu/indiv/l/loom/gene%20expr/overview.jpg 5 Mutations matter Source: damnyouautocorrect.com Warning: frank language & annoying site design 6 Mutants among us ❖ Blue eyes stand up. Green too ❖ Congratulations. You’re mutants 7 Seeing eyes 8 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 ❖ 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! 9 You’ve seen this before ❖ What does it mean? A a A AA Aa a Aa aa 10 11 Look into my eyes... ❖ or his/hers... 12 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. ❖ 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... 13 14 How did blue-eyed freaks of nature arise? does it keep happening?!? Plagiarism? ❖ 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? 15 Provoking your thoughts ❖ Blue eyes arise from a DNA change that decreases creation of melanin in the eye specifically ❖ Mutation appears identical in single origin ❖ On green eyes --they are dominant to blue all blue-eyed folks, suggesting 16 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 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 18 19 Why are you still here? If blu 20 Of mice & men Variety is the spice of mice Moving to the beach ❖ mouse pigmentation is coding sequence Fig. 25-4 21