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Biological Sciences

Bio Lecture 1 1/22/14 Classification Review and Virology: 26.1: Phylogenies show evolutionary relationships 19:1: a virus consists of nucleic acid surrounded by a protein coat 19:2: Viruses replicate only in host cells Phylogeny: is the evolutionary history of as species or group of related species produced using systematic, the collection of fossils, molecular, and genetic data to infer evolutionary relationships a. Independent evolution from a common ancestor 26.1: Phylogenies show Evolutionary relationships a. To understand evolutionary relationships: must provide ordered divisions and naming of organisms (taxonomy) 1. Binomial: genus (first letter is capitalized) + unique epithet 2. Entire species name is italicized 3. Related genera are placed in one family, similar families in one order Hierarchical Classification a. Linneaus introduced system for grouping species in increasingly broad categories b. Taxonomic groups: domain, kingdom, phylum, class, order, family, genus, species Linking Classification and phylogeny a. Systematic depicts evolutionary relationships in branching phylogenic trees b. Taxonomic unit at any level of hierarchy is called a taxon c. Each branch point represents the divergence of two species d. LOOK AT FIGUE 26.4 1. 1= most recent ancestor of the weasel (musterlidae) and dog (canidae) families 2. 2= most recent common ancestor of coyotes and gray wolves e. Systematists interpret a phylogenic tree as recognizing groups that include a common ancestor and its decendants 1. Basal taxon: diverges early in history of a group and originates near the common ancestory of the group (taxon G) 2. Polytomy: is a branch of which more than two group diverge 3. Sister taxa: the closest relatives in a phylogenic tree From two Kingdoms to Three Domains a. Early taxonomists classifies all species as either plants or animals 1. Later 5 kingdoms were organized: Monera(prokaryotes), protista, plantae, fungi, and animalia 2. More recently, the three-domain system has been adopted: - Bacteria, archaea and eukarya - The thee-domain system is supported by data from sequenced genomes A Simple tree of Life a. The tree of life suggests that eukaryotes and archea are more closely related to each other than bacteria 1. The tree of life is based largely on rRNA, as they evolved slowly 2. There have been substantial interchanges of genes between organisms in different domains - Horizontal gene transfer: is the movement of genes from one genome to another - Horizontal gene transfer occurs by exchange of transportable elements and plasmids, viral infection, and fusion of organisms 3. So horizontal gene transfer complicates efforts to build a tree of life Concept 19:1: A virus consist of a nucleic acid surrounded by a protein coat a. Viruses lead “a kind of borrowed life” between life-forms and chemicals 1. Viruses were detected indirectly long before they were actually see - 1935: Wendell Stanley confirmed infections particle smaller than bacteria caused disease, tobacco mosaic disease 2. The origins of molecular biology life in early studies of viruses that infect bacteria - Bacteriophages can infect and set in motion a genetic takeover of bacteria, such as Escherichia coli Structure of Viruses: a. Viruses are not cells, instead virus is small infections particle consisting of nucleic acid enclosed in a protein coat and sometimes a membranous envelope b. Viral genomes may consist of either:
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