Download Understanding Genotype and Phenotype: Efficiency and Evolution in Biology - Prof. James J. and more Study notes Introduction to Cultural Anthropology in PDF only on Docsity! ANTH 102: Humans are cultural animals Course website: http://weber.ucsd.edu/~jmoore/courses LECTURE #9: Genotype and phenotype continued • Reminder: MIDTERM. 3 short essays, then mix of objective & short answer. Lectures are designed to complement, not repeat, readings. If you don’t keep up with readings, you won’t even be able to ask for clarification. Related: sections are not mandatory; your call. But we are trying to meet you halfway. Just how complex? Nematode worm Rabies - virus (not even “live”) that alters behavior in specific fashion - heightens aggression (bite spreads virus) http://www.ThisAmericanLife.org/ Radio_Episode.aspx?episode=319 The point[s] • Lay basis for understanding gene --> phenotype (morphology, physiology, behavior) as a chemical process • The codon length story: a) System is most efficient possible given starting point of complementary code and 4 nucleotides - natural selection optimizing. b) Starting with 6 nucleotides would have been more efficient (2-nucleotide codons, 62 = 36 which > 20+/-); just didn’t happen; natural selection works with what it has - contingent. c) Consequence of contingent optimizing was evolution of a code with lots of redundancy, “slop” in system. Protein synthesis A molecular machine. Look at it in action: Protein is sequence of !! that as a result of specific sequence folds into a specific shape that does stuff. CAUTION: Film advocates intelligent design, makes it all look orchestrated. Reality is molecules bouncing in solution. Remember, dynamite explosion is chemical reaction… Unlocking the Mystery of Life Protein synthesis - the Star Trek version CAUTION: Film advocates intelligent design, makes it all look orchestrated. Reality is molecules bouncing in solution. Remember, dynamite explosion is chemical reaction… Unlocking the Mystery of Life Chromosomes - Linkage Recombination could lead to e.g., A B c, but odds against it. Given assumption that alleles neutral, at equlibrium, calculate expected haplotype frequencies. If b favored, though, frequency of b increase (selection) and so does a, via linkage, relative to c. Use linkage disequilibrium to indicate selection. Contrary to Mendel’s model of independent assortment. Chromosomes - Linkage Recombination could lead to e.g., A B c, but odds against it. Given assumption that alleles neutral, at equlibrium, calculate expected haplotype frequencies. If b favored, though, frequency of b increase (selection) and so does a, via linkage, relative to c. Use linkage disequilibrium to indicate selection. Contrary to Mendel’s model of independent assortment. Silent mutations can accumulate. Recessive alleles can be “protected” from selection by dominants Alleles can be favored by proximity to others Mechanisms by which genes can change to produce new traits, despite the fact that vast majority of (functional) mutations are negative. Digression: Intelligent Design & Irreducible Complexity The argument is that some phenomena - origin of life, molecular “machinery” such as flagellum of bacteria -- are irreducibly complex; all the parts must be present & working or nothing happens. EG: Without RNA, DNA is just a long molecule. Without DNA, how would RNA duplicate itself and evolve? That clip did look designed, didn’t it? Intelligent Design Unlocking the Mystery of Life ID, evolution, & creationism Despite video of Galapagos animals, the irreducibly complex mechanisms cited are all either (a) intracellular, or (b) not irreducibly complex. Nothing in ID conflicts with standard evolutionary understanding of the world since the Cambrian. Nearly all scientists reject on methodological (among other) grounds. Many Young-Earth Creationists reject because ID accepts age of Earth, and has no argument against human evolution from an ape-like ancestor.
