BIOL 3350 1st Edition Lecture 5 Outline of Last Lecture I. Plato’s notion of the typeII. European thought during the RenaissanceIII. Scala Naturae or the Great Chain of Being – AristotleIV. The Scientific RevolutionV. Focus on cataloging and describing speciesVI. Discovering a World in FluxVII. Early Ideas on Evolutionary ChangesOutline of Current Lecture I. The Anatomy of a Scientific PaperII. Pigment Molecules in Beach MiceIII. Genetics of Beach Micea. Substitution Mutationb. Consequence of Mutationc. The Role of the MC1R ProteinCurrent LectureI. The Anatomy of a Scientific Papera. 3 or more authors - et. al.b. Introduction - history/why article was written, background, sets the stage for the experiment that is coming in the paperc. Results – include graphs, tables, charts, statistics obtained in the experimentd. Some scientific papers now put the Method section at the end because not all people really read it unless they are interested in carrying out a similar experimentThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.e. Really good papers come up with a series of hypotheses to testf. Discussion – talk about if your results fit your hypotheses, talk about ideas why results occurred the way they did, designed to set your study up for future research (next step in this line of research)g. Conclusion – explain what you learned; sometimes combined with the discussionsectionh. Empirical evidence – data driveni. Acknowledgements – where the scientists got their funding, who supported them, etc.II. Pigment Molecules in Beach Micea. Two pigment molecules in mice fur: eumelanin (produces darker colors) and pheomelanin (produces light colors)b. Why do some melanocytes produce eumelanin while others do not?c. A transmembrane protein, the MC1R is stimulated by a hormone called the alpha-melanocyte stimulating hormone (alpha-msh)d. When the MC1R protein is stimulated by alpha-msh, lots of eumelanin is producede. When the MC1R protein is stimulated, it facilitates cAMP productionf. Lots of cAMP within a melanocyte cells will facilitate the expression of at least 4 genes g. These 4 genes produce enzymes that lead to eumelanin productionh. When cAMP is scare, these genes are not as readily expressedi. One of the genes, c(tyr), may still be expressedj. If c(tyr) is not expressed, it can result in no pigment production à white mouseIII. Genetics of Beach Micea. Substitution Mutationi. The mc1r genes is located in chromosome #16 in mammalsii. It codes for the MC1R protein that is involved in cAMP production which stimulates the genes involved in eumelanin productioniii. A single nucleotide substitution mutation in the mc1r genes causes a change in amino acid #67 in the Mc1R protein chainiv. When amino acid #67 is cysteine, the MC1R protein is unable to bind the alpha-MSH1. This changes the pigment pathway and eumelanin is not producedb. Consequence of Mutationi. A single nucleotide mutation from a Cytosine to a Thymine changes the amino acid in position #67 from a Arginine to a Cytosineii. Mechanism: Alleles of mc1r Geneiii. Mc1r gene has 2 alleles: R and Civ. The genetic code for these two alleles differs by a single nucleotidec. The Role of the MC1R Proteini. When amino acid #67 is cysteine, the MC1R protein is unable to effectively bind to alpha-MSHii. 2 possible genotypes associated with mc1r gene: RR (dark), RC, CC (light)iii. There is a relationship between the allele type of the beach mice and the genotypes they
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