ECOL/MCB 320 and 320H GeneticsInstructorsDr. C. William Birky, Jr.Dept. of Ecology and Evolutionary BiologyLecturing on• Molecular genetics• Transmission genetics• Population and evolutionary geneticsDr. Linda RestifoDivision of Neurobiology, Arizona ResearchLaboratoriesLecturing on• Developmental genetics• Cancer geneticsTeaching AssistantsGaby WlasiukDept. of Ecology and Evolutionary BiologyCarlos FloresDept. of Ecology and Evolutionary BiologyMike DellingerDept. of Molecular and Cellular BiologyCourse Procedures and PoliciesREAD THE COURSE WEB SITE (yes, the WHOLE thing, except for theschedule of lectures, which isn’t finished) before Friday.http://eebweb.arizona.edu/courses/ecol320/index.htmlThe Honors course web site deals only with things unique to320H.You are responsible for reading and knowing all the of the courseprocedures and policies, times of exams, policies on missedexams and assignments, grading, etc., etc.If you have questions, read the web site before asking us.Read the announcements every week; most will be left on for onlyone week.Web site will have grade tracker where you can see your grades.Must have password; write it on the student questionnaire.Diversity and Uniformity of LifeTake-home lessons:• Diversity of life is under-appreciated, especially for microorganisms.• There is both great diversity and great uniformity in genetics.• Diversity is seen especially in life cycles; uniformity is seen especially inmitosis, meiosis, and molecular genetics.Diversity and Uniformity of LifeTwo points:1. Diversity of life is under-appreciated.2. Some aspects of genetics are highly diverse, while others are nearlyuniform among all organisms.1. Diversity of lifeThree major groups: Eukarya (cells have nuclei), Bacteria, and Archaea.•Two different ways of showing same evolutionary relationships.•Root of the tree = common ancestor of all organisms.•Each of these three groups contains many species.Bacteria Archaea Eukarya2 Bya> 3 ByaDiversity and Uniformity of LifeDiversity of planktonic bacteriain 2.2-litre water sample from anestuary in northeasternMassachusetts. Anonymous PCRand sequencing of SSUrDNA ofbacteria. Results gave estimate of443-1113 species of bacteria.Note the application of geneticsto study the diversity of life andquestions of ecology andevolution.Morphological diversity limited:AS ?S/AAS/AAS/AASS/AADiversity ofeukaryotesand their life cycles.S = Sexual onlyA = Asexual onlyS/A = Sexual andasexualPossible locations ofrootKomodo DragonAS ?S/AAS/AAS/AASS/AAHomo sapiens?AS ?S/AAS/AAS/AASS/AAHomo sapiens?Beetle DiversityDiversity of OrganismsMost of the named groups of organisms actually include hundreds,thousands, or millions of different species.Macroorganisms vs. microorganisms:•Macroorganisms are some Animals, some Fungi, most Land Plants, afew algae.•All the rest are microscopic microorganisms.•There are probably more described species of macroscopic organismsthan of microscopic organisms.•Surveys of molecular diversity suggests that the majority of biologicaldiversity is in the microorganisms.•There is evidence that many microscopic species haven't beendiscovered, or are known only from DNA sequences.•Many microscopic species that have been described haven't beenstudied at the molecule level and put on the tree.• Most of what we know about genetics is based on a small number of “modelorganisms”.• Most of these are macrooganisms.• All are animals, plants, fungi, or bacteria.• Genomics (sequencing complete genomes, i.e. all the genes and other DNA inan organism) is done mainly on organisms that are important for human healthor food, or are model systems.Partial list of model organisms:Organisms Used to Study Genetics• Homo sapiens us• Mus musculus house mouse• Drosophila melanogaster fruit fly• Caenorhabditis elegans a nematode• Zea mays maize• Arabidopsis thaliana a cruciformplant• Saccharomyces cerevisiae baker’syeast• Schizosaccharomyces pombefission yeast• Neurospora crassa bread mold• E. coli an enteric bacterium• Bacillus subtilis a spore-formingbacteriumUniformity in GeneticsUniformity in genetics is seen in the following examples:• Genes = base sequences in DNA molecules• One chromosome = one DNA molecule with many genes on it• Genetic code similar in all• Basic processes of DNA replication, transcription, translation• Some genes are found in all organisms• All eukaryotes have mitosis and mechanism is nearly identical• Meiosis is nearly identical in all eukaryotes that have it• All organisms have recombination due to crossing-over and gene conversion,although the mechanisms may differ in eukaryotes and prokaryotesDiversity in Genetics• Diversity in genetics is seen in the following examples:• Diversity in sequences of genes. The diversity shown in the trees is diversityof gene sequences. All of this diversity can be seen in a single large gene, e.g.SSU rDNA.• Genome size varies ca. 106 – 1011 bp• Number of genes varies ca. 500 – 30,000• Number of chromosomes varies 1– several hundred• Arrangement of genes on chromosomes• Number and kind of transposable elements and introns• Weird variations: e.g. RNA editing, the ciliate macronucleus, imprintingDiversity in GeneticsDiversity in genetics is also seen in life cycles:Bacteria and Archaea• no mitosis, but when cell divides, partitions chromosome 1 copy to eachdaughter• no meiosis or fertilization, but has several other ways of exchanging genes (sex)Diversity in GeneticsDiversity in eukaryotic life cycles:• asexual reproduction by mitosis• sexual reproduction by meiosis and fertilization• diverse life cycles with different combinations of these• most common life cycle includes haploid and diploid cells, both of whichreproduce asexually by mitosis, with occasional sexual reproduction byfusion of haploids to start diploid phase, followed by meiosis to producehaploids• some eukaryotes reproduce only sexually (but how do our cells reproduce?)• some eukaryotes reproduce only asexually; some in every major group exceptmammals and birds• sexual reproduction varies from extreme inbreeding (mating with closerelatives, even with one's self) to outcrossingEukaryotic Life CyclesAsexual life cycle = mitosisSexual life cycle = meiosis + syngamyDiversity and Uniformity of LifeTake-home lessons:• Diversity of life is under-appreciated, especially for