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This 10 page Class Notes was uploaded by Amalia Cristiano on Friday February 6, 2015. The Class Notes belongs to 24010 at San Diego State University taught by Berta in Spring2015. Since its upload, it has received 53 views. For similar materials see Biology 204 in Biology at San Diego State University.
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Date Created: 02/06/15
February 26 2015 Prokaryote motility Flagella Internal fibrils Gliding motion Gas vesicles Some bacteria have fimbriae attachment pilifunction in adhesion Prokaryote Cell Walls Most bacteria and archaea have a cell wall Bacteria cell wall contains peptidoglycan polymer of amino sugar units Archaea cell walls lack peptidoglycan also differ in membrane chemistry RNA polymerase tRNA structure Gram stain separates Bacteria into 2 groups Grampositive pick up violet dye have thick outer peptidoglycan cell wall layer Gramnegative don t stain violet only pink counterstain have thin peptidoglycan layer have outer membrane lipopolysaccharides can have outer capsule tend to be more virulent Prokaryote Reproduction 0 Most asexual fission very rapid cell division 20 minutes 0 A few exchange genetic material but no meiosis Starting with 1 bacterial cell With no limit to cell division at 20 minutes per division 272472X1021 4720000000000000000000 after only one day ca no grains of sand on earth Therefore bacteria can evolve relatively quickly by rapid reproduction amp mutation 9 million per day in E coli of 1 human gut Genetic recombination in Bacteria amp Archaea 1 Transformation uptake of foreign DNA from outside into cell then homologous DNA exchange 2 Transduction phages bacteriophages which are viruses that infect bacteria transfer bacterial genes from one host to another 3 Conjugation DNA transferred 1way from one bacterial cell to another Sex pilus pulls one cell to another Mating bridge allows transfer of DNA plasmids or parts of chromosomes Plasmids small circular pieces of DNA Fplasmid allow mating bridge Fertility Rplasmid allow antibiotic Resistance Prokaryote Metabolism 0 Require oxygen aerobic Don t require oxygen anaerobic obligate anaerobes 02 poisonous can t survive in its presence facultative anaerobes can live in presence of 02 but don t need it Prokaryote MetabolismNutrition 1 Energy needed 2 Source of carbon needed Photoautotrophs photosynthetic energy source is light carbon source is C02 Found in some Bacteria Archaea amp Eukarya e g plants E g Cyanobacteria use chlorophyll and produce oxygen byproduct 6C02 6H20 gt C6H1206 602 quotoxygenicquot photosynthesis Changed atmosphere of earth ca 23 billion years ago from anoxic to oxygenrich Photoautotrophs photosynthetic energy source is light carbon source is C02 Other bacteria use other pigments bacteriochlorophyll retinal produce e g sulfur as byproduct Photoheterotrophs energy source is light carbon source is organic compounds from other organisms Found in some bacteria e g Rhodobacter purple nonsulfur bacteria Chemoautotrophs energy source is oxidation of inorganic compounds e g ammonia nitrite H2 HS Sulfur carbon source is C02 Found in some Bacteria many Archaea Including Archaea from deepsea vents Chemoheterotrophs energy source and carbon source is highenergy organic compounds from other organisms Found in Bacteria Archaea and Eukarya saprobes dead decaying organic material symbionts pathogens parasites on liVing organisms commensalisticmutualistic liVing onWithin liVing organisms Nitrogen xation N2 atmospheric nitrogen gt NH3 NH4 Rhizobium bacterium lives symbiotically with legume roots enzyme nitrogenase Other Nitrogenfixing bacteria N2 atmospheric nitrogen gt NH3 ammonia nitrogenase E g Some Cyanobacteria bluegreens Cyanobacteria N2 fixers symbiotic relationship with Azolla an aquatic fern important in rice production symbiotic relationship With some cycads Pathogenic diseasecausing bacteria Invasiveness ability to multiply Within host E g anthrax has high invasiveness Toxigenicity ability to produce toxins Eg diphtheria has high toxigenicity Endotoxins lipopolysaccharides in outer membrane of some bacteria released When bacteria lyse burst open Eg Salmonella E coli toxic strains Exotoxins proteins secreted to outside by living bacteria very toxic E g tetanus botulism cholera plague anthrax syphilis a spirochaete bacterium a sexually transmitted disease Staphylococcus staph infections Streptococcus e g form of pneumonia strep throat chlamydia very tiny bacteria cause of some sexually transmitted diseases pneumonia etc Actinomycetes form branched filaments resembling fungi tuberculosis Mycobacterium tuberculosis Streptomyces source of streptomycin many other antibiotics some even occur inside plants Mycoplasmas lack cell walls some among smallest organisms some cause diseases animal and plant Endospore protective resting phase of some spp heat drought UV light resistant can remain dormant for very long periods some pathogenic bacteria form endospores eg C botulinum causes botulism Mutualistic symbiotic bacteria 1 Intestinal bacteria eg E coli in humans 100 trillion in our guts 10X no human cells 35 lbs Fecal Microbiont Transplant FMT new area of active research Can be effective against Clostridium di icile lifethreatening diarrhea and on Chron s disease chronic in ammation of the gastrointestinal tract autoimmune response and colitis 2 Bacteria digests cellulose in gut of Trichonympha a ciliate that lives inside the gut of termites 3 Bioluminescent bacteria fish Useful Bacteria Bioremediation remove pollutants e g oil plastics DNA Sequencing Thermus aquaticus thermophilic chemoautotropic bacterium source of taq polymerase used in sequencing reactions Genetic engineering synthesize hormones antibiotics ethanol Archaea Many live in extreme environments thermophilic heatloving acidophilic acidloving sulfur loving e g hydrothermal vents methanogenic methaneproducing release 2 billion tons of methane into atmosphere each year 13 from guts of grazing animals eg cows halophilic saltloving Deep sea hydrothermal vents rich in HS hydrogen sulfide Temperature at vent gt400 C but just around 4 C nearby Chemoautotrophic Archaea use HS as energy source live symbiotically with animals e g giant tube worms Eukaryotes Loss of cell wall enabled endocytosissubstances taken up by membrane invagination Protists Protista Protists sometimes recognized as a Kingdom but is a highly DaraDthetic grout Endoplasmic Reticulum Site of chemical reactions protein synthesis Lysosomes digestion Peroxisomes Chemical reactions Endosymbiosis One cell liVing Within another ancestral engulfment of bacterium by a eukaryotic cell origin of mitochondria and chloroplasts Some lateral transfer of DNA occurred between the DNA of chloroplasts amp the nucleus E g RuBisCo Ribulosebisphosphate carboxylase catalyzes C02 fixation in photosynthesis small subunit genes in nuclear DNA large subunit genes in chloroplast DNA Mitochondrion functions in respiration oxidative phosphorylation DiplomonadsParabasalids lack or reduced mitochondria Mitochondrial lossreduction thought secondarily derived Diplomonads intestinal parasite cause of giardiasis Parabasalids sexually transmitted either malefemale genitalia Chlorophyll a and b slightly different chemically Storage paramylon Kinetoplastids include trypanosoma cause of sleeping sickness 80 chance of death if not treated kills 3 million livestock each year Typically in tropical areas Rhizaria Two major groups Foraminifera Radiolarians Radiolarians Foraminifera Some secrete shells of silica radiolarians or calcium carbonate foraminiferans Feedingquotaxopodiaquot or quotpseudopodiaquot that extrude from shells Fossilized skeletons make up vast fossilized deposits e g limestone deposits of foram s used in geological dating of sediments Alveolates Monophyletic group Many have alveoli membraneenclosed sacs to periphery of cells Ciliates no cell wall cilia short numerous have a 92 pattern Dino agellates chloroplasts chlorophyll a amp c storage starch alpha14glucopyranoside cell walls absent or in plates thecae agella 2 in grooves important components of plankton primary producers some cause red tide harmful algal blooms natural or humanaccelerated eg Karenia brevis can produce neurotoxins can also deplete oxygen fish kills harm to birds marine mammals can be passed up food chain to humans e g toxic oysters other shellfish some bioluminescent luciferin luciferase Ampicomplexans Sporozoans Include Plasmodium 4 spp direct cause of malaria Requires intermediate host eg mosquito Anopheles spp ca 24 spp infect humans Invade and lyse burst red blood cells in cycles Cryptosporidium ampicomplexan that can be a human intestinal parasite can infect water supplies Sydney Australia 1998 Symptom diarrhea Stramenopiles Monophyletic Group Stramenopile means straw hair referring to agella Most have heterokont cells with 2 agella 1 whiplash smooth 1 tinsel hairy hairs tubular Oomycota Water Molds Formerly classified as Fungi Oon egg mycota fungus Most are saprobes heterotrophs feeding on dead decaying matter e g Saprolegnia Some are parasites heterotrophs feeding on living organisms E g Phytophthora infestans Potato Blight Cause of Irish Potato Famine ca 1845 1 million died 2 million emigrated to US Filaments long chains of tubular cells cell walls with cellulose Coenocytes many nuclei per cell Can reproduce asexually or sexually Chromobionta Brown Plants 0 Chloroplasts with chlorophyll a amp c photosynthetic accessory pigments carotenoids yellow fucoxanthin brownish storage compound chrysolaminarin 11 beta 13 1 beta 16glucopyranoside oil 0 Include Coccolithophore phytoplankton very important primary producers Brown Algae Phaeophytes Brown or greenbrown color fucoxanthin accessory pigment 0 Some complex structure thallus Some with alternation of generations life cycle 0 Cell wall algin alginic acid Used as emulsifier in ice cream soups cosmetics etc emulsifierkeeps ingredients from separating Used in dentistry tooth impressions Harvesting of kelp Macrocystis in San Diego Diatoms 2 forms centric and pennate Cell walls in 2 interlocking halves composed of silica Economic Importance of Diatoms Important components of phytoplankton as primary producers Diatomaceous earth fossilized mined remains of diatom cell walls Uses filtering polishing stabilize dynamite y repellant e g for livestock Diatoms can produce neurotoxins too 0 Pseudonitzschim if too much Nitrogen from water pollution will produce excess domoic acid a neurotoxin mimics glutamic acid affects seals permanent short term memory loss Red Algae RhodobiontaRhodophyta Chloroplasts chlorophyll a amp d accessory pigments phycobilins amp phycocyanins resemble blue green bacteria Cyanobacteria storage compound oridean starch alpha 14glucopyranoside with many 16 branches All cells lack agella Cell walls carrageenans agar some outer calcium carbonate layer Red Algae can have complicated life cycles e g two diploid phases Economic Importance of Red Algae 0 Some edible Dulse Nori used to wrap sushi Some harvested for carrageenans amp agar carrageenans used as emulsifiers in foods e g ice cream amp other products agar used as microbiological culture medium Amoebozoans quotamoeboidsquot now thought to be close to fungi amp animals Unikonts pseudopodia armlike extensions of cytoplasm phagocytosis type of endocytosis using pseudopodia surround and engulf prey contractile vacuoles in some remove excess water Some amoeba entamoebae are parasites Eg Entamoeba histolytica Cause of amoebic dysentery spread by contaminated food water eating utensiles causes over 100000 deaths per year 3rd leading cause due to eukaryotic parasites Amoebozoans Slime Molds Formerly like water molds classified as fungi Acellular slime molds One huge multinucleate cytoplasmic mass called a plasmodium don t confuse With genus Can slowly move over a substrate and digest it Exhibit cytoplasmic streaming outer cytoplasm uid motile Feed by phagocytosis like a huge amoeba Cellular slime molds composed of cells mxyamoebae that aggregate together into SLUG pseudoplasmodium Ancestral type of multicellularity
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