Bio 201 F09 True lect 11 (L11)v2r

Bio 201 F09 True lect 11 (L11)v2r -...

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Unformatted text preview: hGp://www.solu@ons‐ 051209_jellyfish2_h2_golden440.jpg today’s factoid •  •  'Jellyfish and Ocean Mixing' on Biology in the News on BB Jellyfish movements, for example daily movements following light to support their photosynthe@c symbionts, may be an important mechanism for mixing ocean and lake waters this movement acts to s@r carbon and nitrogen compounds around bodies of water; process is called "biomixing" story describes the work of researchers in saltwater lakes in Palau in the Western Pacific hGp:// •  •  st mid term exam 1 •  •  •  •  •  •  •  •  Wed. September 30th in class covers material through 9/23 lecture (first 10 lectures) prac@ce ques@ons are posted; review sessions posted Be on @me –  >10 min late will not be allowed into room Bring only your ID and pencils –  All other materials have to be le] on periphery of the room 35 mul@ple choice ques@ons + 3 bonus factoid ques@ons lowest of the three mid terms is dropped, avg. of other 2 = 60% of your grade Only documented medical/family/accident excuses accepted; we need to be NOTIFIED before end of the day on the day of the exam review sessions •  Friday Sept 25th 1:30‐2:30pm. Melissa •  Monday Sept 28th 2‐3pm. Mike •  Tuesday Sept 29th 1‐3pm. Elinor and Alison BRING YOUR QUESTIONS. •  All review sessions will be held in Bio Learning Lab, Rm 026 Life Sciences Bldg. (basement). •  Remember, there are office hours on Monday 9:15‐11:15 AM in 026 Life Sciences, and Tuesday 10‐12:00pm in 601 Life Sciences Metabolic diversity in Prokaryotes •  Prokaryotes have had billions more years than eukaryotes to adapt and evolve •  Much greater metabolic diversity than eukaryotes •  Photoautotrophs (light = energy source, C02 = carbon source) –  Cyanobacteria ‐ use chlorophyll a •  Release O2 as byproduct •  H20 = “electron donor” •  Like eukaryo@c photosynthesis Photosynthe@c bacteria –  Others use bacteriochlorophyll •  Photoheterotrophs (light = energy source, organic carbon = carbon source) –  Purple nonsulfur bacteria •  Do not release O2 •  Some have H2S as electron donor and release Sulfur instead of O2 hGp:// index.php/Rhodobacter chemolithotrophs •  Also called chemoautotrophs •  Use inorganic molecules as energy source, e.g. •  In the deep see near hydrothermal vents –  Communi@es exist with no light –  Inorganic molecules such as H2S come from the volcanic vents –  NH3 or NO2‐(nitrite) ‐> NO3‐ (nitrate) –  Or H2, H2S, Sulfur hGp:// Prokaryotes and Nitrogen •  Denitrifiers can release nitrogen (e.g. Bacillus, Pseudomonas) •  Nitrogen fixing bacteria Bacillus anthracis –  Normally aerobic but in anaerobic condi@ons: 2NO3‐+10e‐+12H+‐>N2+6H20 –  Convert atmospheric N2 to ammonium, which is usable by other organisms N2+6H ‐> 2NH3 •  Crucial for all other organisms •  Nitrogen in proteins, nucleic acids, etc. •  Soil, ocean hGp:// •  Nitrifiers: convert ammonia or nitrite to nitrate hGp:// •  Many prokaryotes cannot be cultured –  Only about 5000 species described Prokaryote rela@onships –  Must obtain DNA samples from nature •  Has revealed the existence of many many more species •  Molecules are now very important in classifica@on and phylogene@cs of prokaryotes •  rRNA genes ‐ present in all organisms •  Problem: lateral gene transfer (also called “horizontal gene transfer”) Rela@onships of major Prokaryote groups Major Prokaryote groups Treponema pallidum, the syphilis pathogen • Spirochaetes •  ram nega@ve G •  hemoheterotrophs c •  ove using axial filaments (see prev. lect) m •  ncludes parasites: syphilis pathogen, Lyme disease pathogen i (Borrelia) Major Prokaryote groups • Chlamydias • smallest bacteria (0.2‐1.5 µm dia.) • Gram nega@ve cocci with complex life cycle • Obligate parasites (apparently cannot produce much ATP by themselves) • Various infec@on types in humans, incl. STD Obligate versus faculta@ve •  Obligate indicates an organism must do some thing –  e.g. Chlamydias are obligate pathogens •  Faculta@ve means an organism can do one thing in one situa@on and another thing in a different situa@on –  e.g. many bacteria that grow as symbionts in animal guts can also grow in isola@on in the laboratory •  (symbiosis means a close, long‐term associa@on) Major Prokaryote groups • High GC Gram Posi>ve bacteria • Also called ac@nobacteria (high GC content in DNA) • Many have filamentous growth • Tuberculosis (Mycobacterium tuberculosis) • Streptomyces species produce many an@bio@cs • note this is a different genus from Streptococcus, which is in the low‐GC Gram Posi@ve group Major Prokaryote groups Some cyanobacteria have cellular differen>a>on • Cyanobacteria • “blue green bacteria” • Photoautotrophs (use chlorophyll a) • Some can perform nitrogen fixa@on • In ancient Earth, transformed the atmosphere by producing Oxygen • Many different growth forms, free living or colonial Major Prokaryote groups • Low‐GC Gram posi>ve bacteria (not all are Gram posi>ve) • Some produce highly environmentally resistant endospores, to survive harsh environments • Can survive for 1000s of years, perhaps longer • This group includes Bacillus anthracis (anthrax), Clostridium botulinum (botulism), Staphylococcus, Streptococcus • Also includes Micoplasma, smallest known cellular organism (.2 µm) Major Prokaryote groups Agrobacterium tumifaciens is a Proteobacteria injects its DNA to transform plant cells a“gene>c engineer” of the bacterial world Crown gall disease caused by Agrobacterium • Proteobacteria • Largest bacterial group, also called “purple bacteria” • Huge diversity, especially in metabolism • Ancestor of the eukaryo@c mitochondria was a Proteobacteria • Includes some nitrogen‐fixers, e.g. Rhizobium • Includes Escherichia coli • Diseases: Yersinia pes>s (bubonic plague), Vibrio cholerae (cholera), Salmonella typhimurium Major Prokaryote groups • ARCHAEA • Much less is known than in Bacteria • Known for extreme environments, but many in less extreme environments • Some have different lipid membrane cons@tuents than bacteria, eukaryotes Major Prokaryote groups • Crenarchaeota • Known for living in very hot and/or very acidic environments • Sulfolobus live in hot sulfur springs (70‐75˚C; pH 2‐3) Major Prokaryote groups Commercial sea salt evapora>ng ponds • Euryarchaeota • Some produce methane (methanogens); obligate anaerobes • In the guts of caGle and other mammals • Important source of atmospheric methane; greenhouse effect • Also known for some extreme environments • e.g. extreme halophiles (very salty environments) • Reddish due to carotenoid pigments • Can withstand highly alkaloid environments (pH ~11) Prokaryotes provide vast and diverse benefits to all life on Earth •  •  •  •  •  Decomposi@on (along with Fungi) Nitrogen cycling Cyanobacteria in ancient Earth ‐> O2 Gut symbionts in animals; aid in diges@on and produce vital compounds, e.g. vitamin B12 Some are pathogenic (minority) –  Human prokaroy@c pathogens are all Bacteria (not Archaea) –  Some produce endotoxins (generally gram nega@ve bacteria) ‐ released when cells lyse •  Usually lipopolysaccharides •  Cause various disease symptoms but are usually not fatal –  e.g. Salmonella –  Some produce exotoxins, highly toxic •  Usually proteins •  e.g. Clostridium (tetanus, botulism), Vibrio (cholera), Yersinia (plague), Bacillus anthracis (anthrax) Our prokaryote friends •  Aid in manufacturing food products –  Along with yeasts (fungi) Our prokaryote friends •  Aid in waste water treatment Our prokaryote friends •  Gene@c engineering and an@bio@cs –  Restric@on endonucleases –  Plasmids –  Agrobacterium transforma@on of crop plants hGp:// applica@ons/posterTool/data/users/ cartoon044.jpg Origin and diversity of eukaryotes (Domain Eukarya) •  How did they evolve? •  Diversity, especially microbial eukaryotes –  Many unicellular forms –  Great reproduc@ve diversity –  Many parasites, important diseases Eukarya Archaea •  Impossible to memorize all of Ch. 27 –  Concentrate on content of this lecture but go through the ques@ons in the book / electronic resources Bacteria Two terms that are no longer used •  Pro@sts ‐ “eukaryotes that are neither land plants, animals, nor fungi” •  Protozoans ‐ microbial eukaryotes that used to be classified as single‐celled “animals” •  Modern phylogene@c systema@cs view indicates that these are non‐monophyle>c groups –  Either polyphyle@c or paraphyle@c Eukaryotes •  Loss of cell wall •  •  •  •  Diges@ve vesicles More complex flagella structure Nuclei Organelles –  Chloroplasts •  A few have lost mitochondria –  Infolding of plasma membrane to increase surface area without increasing volume All of these innova@ons happened on this lineage > 1 billion years ago Eukarya –  Almost all eukaryotes have mitochondria > 2 bya > 3 bya Archaea •  Evolved mul@ple @mes •  Primary, secondary (and even more complex) events Bacteria Loss of cell wall •  Infolding of plasma membrane to increase surface area without increasing volume •  Enables evolu@on of membrane‐bound structures inside the cell One possible sequence of eukaryote evolu@on Loss of cell wall infolding Internal membranes studded with ribosomes Cytoskeleton evolves (microfilaments, microtubules) DNA becomes aGached to a membrane vesicle; precursor to the nucleus Flagellum evolves using cytoskeletal elements; propulsion is possible Diges@ve vacuoles Endosymbio@c event gives rise to mitochondria Endosymbio@c event gives rise to chloroplasts Chloroplasts ‐ mul@ple origins Only glaudophytes retained pep@doglycan The key clue is the number of membranes surrounding the chloroplast 2 = primary 4 = secondary Some lineages have undergone two different events; have two types of chloroplasts (ter@ary, quaternary may have also occurred) ...
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This note was uploaded on 12/22/2009 for the course BIO 201 taught by Professor True during the Fall '08 term at SUNY Stony Brook.

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