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Unformatted text preview: hGp://www.solu@ons‐site.org/artman/uploads/ 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://www.southtravels.com/paciﬁc/palau/gifs/map.jpg • • 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:// microbewiki.kenyon.edu/ 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://www.botos.com/marine/mono3.jpg 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://www.kimicontrol.com/microorg/Bacillus%20anthracis.jpg • Nitriﬁers: convert ammonia or nitrite to nitrate hGp://telstar.ote.cmu.edu/environ/m3/s4/cycleNitro.shtml • 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://cndls.georgetown.edu/ 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.
- Fall '08