Transcript CO 3 2
Interested in Being a Preceptor? • Reinforce your understanding of Bio182 topics • Help peers navigate 182L • Help make the course better • Learn teaching techniques while earning 3 credits Interested in Being a Preceptor? • Work with TAs to teach and develop labs • Travel to exotic locations (okay, not that) • Contact Kevin Baker ([email protected]) for more info (link on Bio182L homepage) Lab 9: In a Family Way Goals for Today: • Understand properties of light and molecules • Dark side of recombination • Develop skill at deducing genotype by observation of phenotype and inheritance patterns What is “color”? And how do we ‘see’ it? Wavelengths (nm) Gamma X-rays Ultrarays violet Shorter wavelength Infrare d Visible light Microwaves Radio waves Longer wavelength nm Higher energy Lower energy Looking in at looking out http://www.bio.miami.edu/dana/pix/retina.jpg Looking Deeper Where are we? The difference between 2 and 3 receptors… Or, the beautiful colors of fall Can ~10 million American males be wrong? http://www.rgblind.com/ http://www.rgblind.com/ http://www.rgblind.com/ What IS ‘color’? Wavelengths (nm) Gamma X-rays Ultrarays violet Shorter wavelength Infrare d Visible light Microwaves Radio waves Longer wavelength nm Higher energy Lower energy The brain’s interpretation of the eye’s report of (three) samplings of a narrow bit of the electromagnetic spectrum Wavelengths (nm) Gamma rays Shorter wavelength X-rays Ultraviolet Infrared Visible light Microwaves Radio waves Longer wavelength nm Higher energy Lower energy If the light is red (680 nm), which receptor do you expect to ‘hear’ it more loudly? ‘green’ receptor How do you get a ‘new’ receptor? What’s in an Opsin • Week 9 calendar: click on ‘Go_Opsin’ link • Retinal eats the photon -> changes shape – Change is directly transmitted to change in opsin (which is holding retinal) • Work through the handout Launch ‘Opsinize’ • Starting with “red-tuned” opsin (559 nm) • Your objective: make a ‘green-tuned’ (as close to 531) nm • Your tool: mutating codon sequences • From each menu you can mutate the codon (which reflects changes in DNA) 3-Letter Code • Leu: Leucine • Ala: Alanine • Arg: Arginine • Lys: Lysine • Asn: Asparagine • Met: Methionine • Asp: Aspartic Acid • Phe: Phenylalanine • Cys: Cysteine • Pro: Proline • Gln: Glutamine • Ser: Serine • Glu: Glutamic Acid • Thr: Threonine • Gly: Glycine • Trp: Tryptophan • His: Histidine • Tyr: Tyrosine • Ile: Isoleucine • Val: Valine Thinking it through… • Shown: the only amino acid differences between red and green opsins • DNA sequences would be… how similar? • What happens in meiosis when the maternal and paternal chromosomes pair? • Think anything might ever go wrong? How do you get a ‘new’ receptor? • What’s the ‘easiest’ way to get a slightly different protein? – Make a new segment of DNA that happens to be similar – Start with a random stretch of existing DNA and randomly mutate until… – Copy the original gene and ‘tweek’ Remember Recombination? Things don’t always go smoothly Where to Recombine? Oooooops 2 How do the restriction enzymes ‘know’ where to cut and recombine? G G G G But…. G G So….. • Is it easier to make a gene, or tinker with an existing one? This one So what if this gamete ‘fertilized’ with... G G G How many colors? G G R G But what if you altered the protein to make it sensitive to a different wavelength NOW what do you have? Red and green 98% similar. Why? “New” Genes – Sound Familiar? “New” Genes – Sound Familiar? • Green -> “Red” Opsin • Myoglobin -> Hemoglobin • Adult vs. Fetal Hemoglobin What’s seX got to do with it? • The “X” is big • The “Y” not so much • What does this mean? What’s seX got to do with it? • Autosomal: chromosome NOT X or Y • Sex chromosome: X or Y (b/c of where each is joined together during meiosis) • Symbolism: normally, we don’t care what chromosome given allele is on; in sex, it matters – On the X, we designate : XA, Xa – On the Y, generally designate: Y How come no A or a? • Hemizygous What’s seX got to do with it? • Consider A and a • How many genotypes for females? Males? • How many possible crosses? – How to distribute What’s seX got to do with it? • Consider A and a • How many genotypes for females? Males? • How many possible crosses? – How to distribute • Do the cross – How can you tell it’s sex-linked? – Compare sex-linked crosses to corresponding autosomal • What is the equivalent of Y? It sucks to be XY • R/G Colorblind • Hemophilia • Different anemias How is this useful? Pedigrees! PTC and parentage • • • • WASH HANDS Who can taste this? Separate into haves, have-nots Each: if trait is dominant, what can you deduce about your parents? • If trait is recessive? Boys vs Girls Makin’ Babies Pair up, decide who’s the adult consenting male & who the similarly conscientious female You’re both heterozygotes (recall: ‘different-pairing’) Make the babies--hold an allele in each hand, partner picks How to determine the sex of the baby? Pediducer Deductions from Pedigrees Two Phases • Phase I: Assign genotypes and justify • Phase II: Rule model “plausible” or “out” Pediducer Rules and Conventions • What assumption about randomly selected, ‘healthy’ individual? • Justification is “Outsider” • REASON must be sufficient & necessary Pediducer Rules and Conventions • What does affected indiv. look like? • You are TESTING models – How many right for model to be right? – How many wrong... • Justification • “Check me” Explore • Menu progression: left to right • If not logged in, first menu tells you what the ‘answer’ is • Third menu specifies the model you are currently considering • You are seeking to prove (how much data?) or disprove model (how many internal contradictions?) NO POINTS!!!!! If you don’t rule models in/out Preparing for next week Let me intreduce myself • RHC=O + H2O => RCOOH + 2H+ + 2e• 2CU2+ + 2e- => 2Cu+ • 2Cu+ + 2OH- => Cu2O (red ppt.) + H 2O Who is oxidized (loses electron ownership--often to oxygen)? Who is reduced? Reagents for glucose (do all three) • 1% glucose • 0.2% glucose • water Capturing CO2 H2O + CO2 -> H2CO3 H2CO3 -> HCO3– -> CO32– CO32– + Ba2+ ->BaCO3 (white ppt.) Do it! • Appendix C--the supplies are on your benches • Do the Benedict’s test on C-1 (substituting 0.1% glucose for the 1% starch indicated) • Candidate solution = glucose • Do the CO2 test on C-2 53 – Place dry ice in flasks with appropriate tubes/stopper – Why dry ice? Homework If you don’t rule models in/out Pedid Three pedig solve plaus out fo three hypot