BIOS 101 Week 8 Notes
BIOS 101 Week 8 Notes BIOS 101
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This 5 page Class Notes was uploaded by Kruti Merchant on Friday March 4, 2016. The Class Notes belongs to BIOS 101 at University of Illinois at Chicago taught by Dr. Brown in Fall 2016. Since its upload, it has received 49 views. For similar materials see Population and communities in Biology at University of Illinois at Chicago.
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Date Created: 03/04/16
Week 8 Notes February 29 (Phenotypic Plasticity) Sophisticated path of genes with environment. ****On exam: 1 question on Tetrahymena Vorax: Single cell protist, they live in fresh water (ponds, stillwater). They have an oral cavity to slurp up bacteria or small algae. Microstone (small mouth). Cilia around mouth for flow. Two things that happen in environment: 1 Bacteria get scarce 2 Other species of cylite lead to competition. Their waste product show how many are there. When this happens, they morph from hairy looking form to macrostone, so they can eat the competition. (Morph into becoming into a predator). Two morphs to allow them to eat at two different trophic levels. Phenotypic plasticity is genetic. You require other genes to morph. (ex. Regulatory gene). To go back to another morph you need to undergo cell division. Yarrow flowering plant, weedy, grows up mountainsides. Reaction norm, in which circumstance it is, it will react differently. Smaller in the top area of mountain. Below areas, they grow bigger, growing season is longer. Common Garden Experiments: Get seeds and switch locations. If it (yarrow) is phenotypic, where you are grown matters. If they are the same genotype, then they would all grow to the same height everywhere. Many of the yarrow died, they showed some phenotypic plasticity but it was not enough for them to survive. They had different genetics. Ex) Barnacles, ECOTYPE (same species but genetic variance adapted for different environments) Many sources of variation: fuels evolution by natural selection. Genes are particulate. Diploids will separate and there will be independent assortment. The inheritance of genes will always be the same, but what is changing is between the genes and the phenotype. Mendel's Law: 1 Within Loci: 2 genes segregate randomly (alleles). 2 Independent assortment: between loci. Mixing and matching, example, tongue rolling and bloodtype. Alleles at different loci, alleles will be mixed and matched. (Unless there is linkage) How did Mendel discover this: He was into quantitative data. Tried to mix seeds and plants. Crossing! Pick and spread pollen elsewhere. Mendel understood that traits did not blend but there was distinction. He noticed traits may show up after skipping a generation. Genetics Problems: ******Chicken problem: Codominant black and white feather. If you breed white with black, you will always get peppered chicken. Breed together peppered chickens, you get 1/4 white, 1/4 black, and 1/2 peppered. Dominant phenotype, you don’t know the alleles, but you do for recessive phenotype. Mendel worked with peas. The seeds are big and easy to grow. Plants are robust. They have a big showy flower (you can breed them). You have to breed 3 generations. Mendel is neutral about Darwin. Crinkly vs. smooth peas. Crossing them, he found that there wasn’t linkage between texture and color. Peas have less then 10 chromosomes. Mendel picked 7 different traits and they all underwent independent assortment, this was impossible. Ignored the linked ones. We won't know because these notebooks were burned. Imagine you have 2 loci ( Aa, Bb) Possible gametes (aB, AB, ab, Ab) More and more loci. No two sperm or no two eggs in this class are the same. nd March 2 (Pleiotropy) 1. Write down the genotypes of parents (P1). Ex) P1 F^W F^B F^W F^B F^W F^B F1 F^WF^B Classic Mendelian Problem: Mathematical relationship in the flowers. Experiments with pea plants. Ex) P1 Purple White PP Pp F1 ------- Pp------- F2 ----PP, Pb, Pb, pp--- Incomplete dominance occurs more with plants. Genotypes blend. Alleles at different loci assort independently. Testing independent assortment: *****(On exam) Test cross Drosophila Melanogaster are convenient to test. P1 se se BK SE SE bk BK bk F1 -------- Se Bk bk se ------- F2 SEBK sebk SEbk seBK Gametes are haploid, not diploid. Chisquare test: (Sum of (Observed -expected)^2)/Expected If you falsify independent assortment, then there might be linkage. If value is above critical value, there is linkage. Codominance: traits are distinct Ex of Linkage) P1 se se eb eb SE SE EB EB F1 SE se EB eb F2 SE se EB eb, SE SE SE SE eb eb, se se EB EB eb eb Wild Type: the allele thought to be the baseline for the wild population. One allele is present in each individual (usually dominant). Mutation cause not having the wild type. (They were wrong about this idea). March 4 (Sex-linked Traits) Sex linkage: form of inheritance that happens because males are heterogametic (XY), females are (XX). In males, they are missing one X chromosome. Diploid for almost all genes. Male produce small gametes (sperm and pollen). Females produce large gametes (eggs). Ex. Mulberry trees have two sizes of gametes. Fruitless are male mulberries. Female mulberries has a lot of berries. They planted male mulberries and then had a lot of pollen, this happened in Tulsan where people have increased chance of hay fever. Birds and butterflies > females are heterogametic. NonHeterogametic Sex Discrimination: Chromosome does not determine size of gametes. Ex) Turtle slider is female because of the temperature of her egg when it was incubated. Otherwise there is no difference between female and male sliders. Alligators can determine the sex ratio just by deciding where to lay eggs (diff temperatures). Ex) Bluehead Wrasse. If you remove males from reef, females will get rid of ovaries and get testes, within around 3 days, they will have fertile sperm. Hetergametic Sex Determination: Homogametic is usually females (XX), expect for birds and arthropods. Heterogametic, are male (XY) Ants, bees, and wasps: Females are diploid (XX), males are haploid (XO). Any trait that is on the sex chromosome, we only have one copy (haploid). Hemophilia: If you are a male, you get the trait from your mom. Dad had Y chromosome. Red, green color blindness: 10% of alleles are carried by men. 9% of males are colorblind. Sex linked trait, you get it from your mom. 1 percent colorblind women, all your sons will be. Ex) Redwhite eyes (heterozygous female) White Eyes (Male) *Exam, questions on offspring. Un cross, when you have a sex linked. Males are haploid, females are diploid. Traits in multicellular, where they will choose to use one allele if one cope (X) will be inactivated. Mostly happens in fur patterns. Ex) Cat that is orange, white, and blackthis is a female! Lots of ways to go from genotype to phenotypes. Most traits of epistatic. Epistasis: one gene alters the gene at another loci. Ex) Some think AAbb is same as aa BB BUT NO, you may get very different phenotypes. Ex) Coat color in mice. If you are homozygous recessive at have C allele, coat will be white. Pleiotropy: Single gene will influence multiple traits (opposite of Epistasis). Ex) Marfan's syndrome, genetic disease. One gene influences so many traits. Fibrillin is formed. Penetrance: When you code for a gene, you may not always see it.
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