Bio lecture 9 25 10 14 09 25 2014 Allopatric Speciation fairly common dependent upon geographic isolation Genetic divergence occurs during the period when they re isolated Overtime speciation will occur Sympatric Speciation occurring in same general area no geographic isolation organisms occur together gene flow increases no genetic divergence something happens gene flow to 0 allowing for increased likelihood of genetic divergence Ex Mutation immediate isolation no gene pool o Snail morphology if coils go different ways mating impossible 1 gene mutation mechanical isolation can also occur thought changes in breeding behaviors locations behavioral isolation ecological isolation permanently isolates populations genetic div speciation Gradualism slow speciation rate intermediate forms before full speciation Punctuated Equilibrium rapid speciation short bursts of evolutionary change often results in mutation Extinction species loss more extinct species than currently living can happen gradually changes in habitat anthropogenic effects drought famine as species are lost every characteristic about them becomes open to new species due to decreased competition could lead to genetic divergence can happen bc of catastrophe like a fire hurricane Asteroids collide with Earth Chicxulub crater one of most famous Yucatan Peninsula No sun for a while leads to winters Rapid new rate of species following extinction Systematics method of classifying naming organisms within an evolutionary framework Goals inventory all living things o Universal system for naming Taxonomy o Determine evolutionary relationships among organisms Carolus Linnaeus wrote Systema Naturea o Rules for how to name organisms o Derived binomial nomenclature Has two names Genus species Homo sapiens o If have same Genus then you ll know they may be commonly related o In Latin universal language for describing organisms o Hierarchical nomenclature K P C O F G S Used to organize group organisms Based upon structural similarities difference Carl Woese o Added Domain above Kingdom o Separated Archaea and Eukarya o Bacteria Archaea Eukarya o Prokaryotes lack membrane bound nucleus o Eukaryotes have membrane bound nucleus Phylogeny Phylogenetics o Technique tool for reconstructing evolutionary history or relationships based upon common ancestry o Fossil records shared characteristics gene sequences o Represented by phylogenetic trees o All trees have a base of a common ancestor o EXAMPLE red algae and chlorophytes and hornworts have shared characteristics that relate them to Vascular plants o You have to map out the traits of each living thing to distinguish what they have in common o On some points of the tree a few living things have different things in common Everything below it lacks that character above possesses that character Viruses Very small Not considered to be living All contain RNA or DNA genetic material be able to distinguish o RNA are constantly changing form difficult to treat o DNA are more stable don t really change Bacteriophage only DNA virus o Helical tail o Head contains DNA o Extremely small o Virion viral particle different way of saying single virus o Two different cycles Lytic Cycle Attachment host recognition attach to cell wall Penetration Use tail to press through wall to inject viral DNA into cell Synthesis viral DNA takes over cellular replication machinery so new virions can be produced Assembly new virions put together from newly synthesized material replicated Release cell lysis bursts causing new virions to escape and infect more cells REPEAT Lysogenic Cycle Resting stage After penetration Complex set of cues can cause this Integration viral DNA integrates into the bacterial genome prophage Propagation viral DNA replicated along with genome continue dividing Induction viral DNA becomes active and goes into Lytic Cycle due to cell stress Animal viruses all RNA Possess a capsid outer protein covering encasing genetic material o Helical corkscrew shape o Icosahedral circular w sides o Icosahedral head shaped in the head has a long body Found only in DNA viruses o Helical capsid within envelope corkscrew capsid surrounded by RNA within circle studded with antigens used to recognize and enter appropriate host cell or exit cell All linked together b c of a capsid and genetic material RNA DNA Phage Conversion o Bacterial host becomes virulent and infectious toxic following o Not harmful bacterial cell becomes very dangerous when bacteriophage infection infected by bacteriophage o Goes into Lysogenic Cycle Some portion of viral DNA expressed o Leads to production of toxins infectious bacteria o Ex Salmonella Diphtheria o Vibrio cholera very dangerous kills many people producing an abundant amount of diarrheal fluid Harmless when not infected by bacteriophage When infected becomes deadly after viral genes are activated Becomes infectious toxic A cholera toxin Colonize in small intestine Spreads rapidly Excessive dehydration vomiting death Very treatable responds to antibiotics well if given ASAP Phage Therapy o Flood infected organisms with bacteria infected by viruses o Eventually rupture virions spread out to infect more o Effective way of treating bacterial infections o Strengthens immune system o Also use Lysin Therapy enzymes derived from viruses that break down bacterial cell walls allows virions to move out Flu viruses RNA viruses Envelope outer covering containing the capsid contains genetic material o Covered with protein spikes antigens 2 types o H antigen hemaglutin o Responsible for host recognition Looking for particular receptors on host cell surface Bonds with receptor which then lets the virus in Once in the cell virus hijacks cellular replication synthesis machinery to build new virions Once built the 2nd protein spike type becomes important N antigen neuraminidase o Responsible for getting virions out of cell o No cell death lysis Keeps producing new virus virus factory We use H and N antigen subtypes to classify flu viruses o About 15 H subtypes 9 N subtypes Lots of potential viral diversity o Likely result of increased mutation rates in RNA viruses o Problematic for vaccine design Fighting a moving target Each new H and N grouping requites new vaccine Also affected by H and N arrangement on envelope Also problematic on immune system Antibodies fight against viruses diseases Antibodies result from exposure to particular viruses infections o Possess them for life Why are RNA viruses
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