Bio Test 1

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Bio Test 1
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2012-02-14 04:00:03
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  1. __________, fungi, and_______ form a clade—the ______
    Choanoflagellates/animals/opisthokonts
  2. Fungi synapomorphies:
    •Absorptive heterotrophy




    •Chitin in cell walls
  3. absorptive heterotrophy
    Fungi's method of obtaining nutrients




    Secrete digestive extracellular enzymes that digest food outside the body, then smaller molecules are moved across cell walls
  4. Saprobes
    carbon and nutrients directly from dead organic matter.
  5. Parasites
    Absorb nutrients from living hosts
  6. Mutualists
    Both partners benefit
  7. Predatory Fungi
    • secrete sticky substances so that passing organisms stick tightly to them and hyphae then quickly invade the prey.




     some soil fungi make a constricting ring that can trap nematodes
  8. hyphae
    Minute threads in multicellular fungi, form an interwoven mat called mycelium
  9. Separate Hyphae
    cells of hyphae are separated by incomplete cross walls or septa with pores that permit organelles to move between cells.
  10. Coenocytic Hyphae
     lack septa – multiple nuclei are located within one cytoplasmic mass.
  11. Most parasitic fungi have haustoria
    haustoria are nutrient absorbing hyphal tips that press into host cells without breaking through the plasma membranes
  12. Saprobic fungi
    Major decomposers on Earth




    §Without fungal decomposers, Earth’s carbon cycle would fail; carbon would be buried.




    §Saprobic fungi return C to the atmosphere as respiratory CO2, available for photosynthesis by plants.




    §Contribute to soil formation and recycling nutrient elements
  13. Lichen
    Mutualistic relationship between fungi and photosynthetic organism
  14. Mycorrhizae




    1) Ectomycorrhizae




    2) Arbuscular mycorrhizae
    Fungi+plant roots




    • 1) Fungi wrap around root
    • 2) Fungi penetrate cell walls of root but not plasma membrane
  15. Asexual reproduction in Fungi
    •Production of haploid spore within sporangia.




    •Production of naked spores at tips of hyphae called conidia.




    •Cell division by unicellular fungi- fission (equal division) or budding (unequal).




    •Breakage of the mycelium.
  16. Plasmogamy
    When hyphae of differing mating types fuse but not nuclei
  17. dikaryotic stage
    •2 genetically different haploid nuclei coexist within same hyphae.




    -Hyphae is neither haploid or diploid, rather it is dikaryotic (n+n)
  18. Karyogamy
    Fusion of the nuclei
  19. •Of the six major groups of fungi, the ______ and _______ fungi are not monophyletic groups, but
    are paraphyletic; they are convenient categories for a general introduction to the fungi.
    Chytrids and Zygospore
  20. 6 major groups of fungi
    Chytrids, Zygospores, Basiomycota, Ascomycota, Microsporidia, Glomeromycota
  21. Dikarya
    Monophyletic group of Basiomycota and Ascomycota
  22. Microsporidia
    •unicellular fungi, obligate intracellular parasites of animals; 1,500 species.




    •They are among the smallest eukaryotes known.




    • •The host cell is penetrated by a polar tube of the microsporidian spore, and the contents of the
    • spore are injected into the host.




    • •The sporoplasm replicates in the host cell and
    • produces new infective spores. 




    •The life cycle of some species is complex and involves multiple hosts.




    • •Microsporidia have cell walls with chitin, and
    • lack true mitochondria; they have reduced structures called mitosomes.




    •DNA sequencing indicates they are highly reduced, parasitic fungi, but exact placement is still debated.
  23. Chytrids
    aquatic fungi, were once classed as protists but have chitin in their cell walls.




    •Have flagellated gametes, some show alternation of generations (like plants), no dikaryon phase




    •Multicellular diploid stage includes a structure that can withstand freezing and drying.




    •Chytrids may be parasitic or saprobic; some are found in foregut-fermenting animals such as cattle and deer.




    •Some chytrids are unicellular, others have rhizoids, still others are coenocytic.
  24. Chytridiomycosis
    Infectuous disease killing amphibians throughout the world, killed ~30%, no effective measure for controlling the disease
  25. Zygospores
    •conjugating fungi”




    •Terrestrial fungi- saprobes on soils, parasites of insects and spiders, as mutualists with other fungi and invertebrates.




    •Zygote is the only diploid cell




    •Hyphae are coenocytic (lack septa)




    •Stalked sporangiophores contain sporangia




    •>1000 species described; includes Rhizopus stolonifer, black bread mold.
  26. Glomeromycota
    • Arbuscular mycorrhizae fungi
    • Coenocytic hyphae
    • Reproduce asexually
  27. Ascomycota
    • Sac fungi
    • produce asci: sacs which contain sexually produced haploid ascospores




    Filamentous sac fungi reproduce asexually by conidia that form at the tips of hyphae 




    Sexual reproduction includes a brief dikaryon
  28. Ascomycetes (2 groups)
    1) Euascomycetes “true”: asci in a fruiting body called an ascocarp.




    -“Cup fungi,” includes morels and truffles




    -Molds, including Aspergillus and Penicillium




    -Ergot—parasite on rye




    -Mildews




    -Parasites on plants such as chestnut blight and Dutch elm disease




    2) Hemiascomycetes “half”: no ascocarp




    -Most are unicellular—yeasts 




    -Baker’s/Brewer’s yeast Saccharomyces cerevisiae
  29. Basidiomycetes
    the “club fungi”




    •Fruiting structures are basidiomata




    •30,000 species, includes edible mushrooms, puff balls, bracket fungi




    •Hyphae have septa with pores.




    •The basidia are the characteristic sexual reproductive structures; site of nuclear fusion.




    • •In mushrooms, basidia form on specialized structures
    • called gills or pores. 




    • •The dikaryon stage may persist for years—some
    • live decades or even centuries.




    •Also include plant pathogens such as rusts and smuts infect cereal grains. Other club fungi species are fungal partners in ectomycorrhizae.
  30. Reproductive Characteristics:




    Microsporidia




    Chytridiomycota
    • Microsporidia = unicellular fungi, 1500 spp.
    • •obligate intracellular parasites of animals
    • •They are among the smallest eukaryotes known.




    • Chytridiomycota = Chytrids, ~1000 spp.
    • §Motile zoospores with flagella.
    • §Mostly aquatic, once considered protists
  31. Reproductive Characteristics:




    Zygomycota




    Glomeromycota
    • Zygomycota =Zygote fungi, >1000 spp.
    • §Resistant zygosporangium as sexual stage.
    • §mostly live in soil




    • Glomeromycota = arbuscular mycorrhizal (AM) fungi, <200 spp. 
    • •Reproduce asexually.
    • •Associate with plant roots. 
    • •Live on roots in soil
  32. Reproductive Characteristics:




    Ascomycota




    Basidiomycota
    • Ascomycota= Sac fungi, ~64,000 spp.
    • •Sexual spores borne internally in sacs called asci.
    • •includes truffles, morels, lichens, some yeasts; some are pathogenic




    • Basidiomycota = Club fungi, ~30,000 spp.
    • •Sexual spores borne externally on club-shaped structures called basidia.
    • •includes mushrooms, rusts, shelf fungi, puffballs, lichens, some yeasts
  33. Mold
    a rapidly growing, asexually reproducing fungus. Molds are used in the production of antibiotics and cheese.  Many molds are classified as “imperfect fungi” because on asexual reproduction is known.
  34. Yeasts
    Unicellular members of the zygomycetes, ascomycetes, and basidiomycetes.The term does not refer to a single taxonomic group but rather to a lifestyle that has evolved multiple times.
  35. Lichens
    Found in both Ascomycetes and Basidiomycetes.  About 15,000 lichen “species” have been described.
  36. earliest prokaryote fossils date back at least ______ years
    3.5 billion
  37. Prokaryotes play key roles in:
    • 1. Organic breakdown
    • 2. Nutrient cycling
    • 3. Diseases of humans and otherorganisms
    • 4. Bioremediation
  38. In 1977, ______ (at Univ of Illinois) revised tree of life into three domains- _________- using differences in the ____ to determine relationships between the organisms.
    Carl Woese/ eukaryotes, bacteria and archaea/rRNA
  39. eukaryotes and______ are more closely related than
    ______and______
    archaea/ bacteria&archaea
  40. •Among the Bacteria, three shapes are common:
    -Sphere or coccus (plural cocci), occur singly or in plates, blocks, or clusters.-Rod—bacillus (plural bacilli)-Helical-Rods and helical shapes may form chains.
  41. •Morphology of known species of Archaea includes _____, _____, _________, and _______
    cocci, bacilli, triangular, and square-shaped; the latter grow on surfaces, arranged like sheets of postage stamps.
  42. Biofilms
    Communities of different species of prokaryotes, including microscopic eukaryotes, excrete a gel-like polysaccharide matrix.
  43. ______ may be impenetrable to antibiotics.
    Biofilms
  44. Bacterial cell walls have_________, a polymer of amino sugars.

    Archaea do not have__________, although some have a similar molecule called________________.
    • peptidoglycan, peptidoglycan
    • pseudopeptidoglycan
  45. Gram-positive bacteria retain the violet dye; they have a _____ layer of peptidoglycan outside the plasma membrane


    Gram-negative bacteria retain the red dye; they have a____ layer of peptidoglycan between the plasma membrane and another distinct outer membrane, in the periplasmic space
    thick

    thin
  46. ____________interfere with the synthesis of the cell walls, but don’t affect eukaryote cells.
    Antibiotics such as penicillin
  47. Quorum sensing
    • •Bacteria can monitor the size of the population by sensing the amount
    • of chemical signal present.

    When numbers are large enough, activities such as biofilm formation can begin.
  48. bioluminescence
    Often the bacteria only emit light when a quorum has been sensed.
  49. Anaerobes
    do not use oxygen as an electron acceptor in respiration.
  50. obligate anaerobes
    molecular oxygen will kill these oxygen-sensitive prokaryotes
  51. Facultative anaerobes
    can shift their metabolism between aerobic and anaerobic modes, such as fermentation
  52. Photoautotrophs
    perform photosynthesis using light as the energy source, and CO2 as their carbon source.
  53. Photoheterotrophs
    are bacteria that also use light as an energy source, but get carbon from organic compounds made by other organisms
  54. Chemolithotrophs
    get their energy by oxidizing inorganic compounds, and use the energy to fix CO2 as their carbon source.
  55. Chemoheterotrophs
    obtain both energy and carbon from complex organic compounds
  56. Flowchart of nutritional mode of organisms
  57. 3 reasons why nucleotide sequencing of ribosomal RNA is useful in evolutionary studies:
    -rRNA is evolutionarily ancient and all free-living organisms have rRNA

    -rRNA has the same role in translation in all organisms, lateral transfer is unlikely

    -rRNA has evolved slowly; sequence similarities are easily found
  58. Lateral gene transfer
    occurs when genes from one species become incorporated into the genome of another species (moving “sideways” in the tree).
  59. Mechanisms
    transfer by plasmids or virus, and uptake of DNA via transformation

    •Transfer can occur between the domains.
  60. hardy weinburg/isotopic decay
    LOOK THIS SHIT UP
  61. •Over __ clades of bacteria have been proposed under the currently accepted classification scheme.


    We will focus on examples from __ clades
    12

    6
  62. Spirochetes
    Bacteria

    •Gram-negative, motile, chemoheterotrophic; they have unique axial filaments (modified flagella) that rotate.

    •Many are human parasites, some are pathogens (syphilis, Lyme disease), others are free living.
  63. Chlamydias
    Bacteria

    •Extremely small, gram-negative cocci, live only as parasites within cells of other organisms. Can take up ATP from host cell with translocase.

    •Complex life cycle w/ two forms- elementary bodies and reticulate bodies.

    •Some are pathogens causing sexually transmitted diseases, some pneumonia.
  64. High-GC Gram-positives (actinobacteria)
    Bacteria

    •High G-C/A-T ratio in DNA

    •Form elaborately branching filaments, some reproduce by forming chains of spores at tips.

    •Most antibiotics are from this group, also includes Mycobacterium tuberculosis.
  65. Cyanobacteria
    Bacteria

    •Photoautotrophs use chlorophylla; produce O2

    •Often associated with polluted conditions.

    •Some can fix nitrogen via specialized cells known as heterocysts.

    Eukaryote chloroplasts are derived from endosymbiotic cyanobacteria
  66. Low-GC Gram-positives (firmicutes)
    • Bacteria
    • •Low G-C/A-T. mostly gram-positive (includes Staphylococcus, and organisms responsible for anthrax and botulism), but some are gram-negative; some have no cell wall

    •Some produce endospores—heat-resistant resting structures; can survive harsh conditions because it is dormant.

    •Endospore becomes active and divides when conditions improve.

    •Mycoplasmas have no cell wall, are extremely small, and have very small genome. May be the minimum amount of DNA needed for a living cell.
  67. endospores
    • (firmicutes)
    • heat-resistant resting structures;
    • can survive harsh conditions because it is dormant.
  68. Mycoplasmas
    • (firmicutes)
    • have no cell wall, are extremely small, and have very small genome. May be the minimum amount of DNA needed for a living cell.
  69. Proteobacteria (purple bacteria)
    •Largest group of bacteria—high diversity of metabolic phenotypes.

    •Common ancestor was photoautotrophic; as they encountered new environments, the delta and epsilon groups lost ability to photosynthesize. In other 3 groups, some evolutionary lineages became chemolthotrophs or chemoheterotrophs.

    •Includes some nitrogen-fixing genera such as Rhizobium; E. coli is also proteobacterium.

    •Proteobacteria that are human pathogens: Yersinia pestis (plague), Vibrio cholerae (cholera), and Salmonella typhimurium (gastrointestinal disease).
  70. Archaea
    •The separation of Archaea was originally based on rRNA gene sequencing; supported by sequencing an entire genome—more than half the genes were unlike any in the other two domains.

    •Archaea are famous for living in extreme environments: high salinity, high temperatures, high or low pH, and low oxygen. But many others live in habitats that are not extreme (e.g. soils).
  71. Archaea are divided into two main groups,___________ and__________, plus 2 recently discovered groups
    Euryarcheota, Crenarcheota
  72. _______ are known only by evidence from DNA isolated from hot springs.
    Korarchaeota
  73. ________ are named due to their small size. Discovered in deep sea vents off Iceland; they live attached to cells of the crenarcheota Ignicoccus.
    Nanoarchaeota
  74. •Two characteristics shared by ALL Archaea:
    1. no peptidoglycan in cell wall

    2. Distinct lipid composition of cell membrane
  75. Most bacterial and eukaryotic membrane lipids unbranched
    long-chain fatty acids connected to glycerol by __________.

    Unique Archaea lipids contain long-chain
    hydrocarbons that are branched, and connected to glycerol by __________.
    ester linkages.

    ether linkages (are a synapomorphy for archaea)
  76. lipid bilayers and lipid monolayers are both found in the______.
    Archaea
  77. Crenarcheota
    • Archaea
    • are both thermophilic and acidophilic (acid-loving).
  78. Euryarcheota
    • Some are methanogens; they produce methane (CH4) by
    • reducing CO2 (obligate anaerobes).

    Methanogens release 2 billion tons of methane per year. Many live in the guts of grazing mammals.

    Increased cattle farming and rice growing contributes methane to the atmosphere.
  79. •Extreme halophiles
    (salt lovers) have pink carotenoid pigments, easy to see. They have been found at pH up to 11.5. They live in the most salty, most alkaline environments on Earth.
  80. Thermoplasma
    is thermophilic and acidophilic, has no cell wall, aerobic metabolism, and lives in coal deposits; it has the smallest genome of the Archaea and its genome size is comparable to mycoplasmas.
  81. Consequences of infection depend on:
    Invasiveness of the pathogen—its ability to multiply in the host.

    Toxigenicity of the pathogen—its ability to produce toxins.
  82. Corynebacterium diphtheriae
    (diptheria) has low invasiveness, but the toxins it produces affect the entire body.
  83. Bacillus anthracis
    (anthrax) has low toxigenicity, but very high invasiveness—colonizes the entire bloodstream.
  84. Endotoxins
    (type of bacteria toxin)are released when certain gram-negative bacteria grow or lyse, are lipopolysaccharides forming part of outer bacterial membrane.
  85. Exotoxins
    (type of bacteria toxin) are soluble proteins released by living bacteria. Are highly toxic and often fatal.
  86. protists
    Eukaryotes that are neither plants, animals, or fungi

    do not constitute a clade, they are paraphyletic
  87. paraphyletic
    group contains its most recent common ancestor but does not contain all the descendants of that ancestor
  88. Monophyletic
    contains all the descendants of the possibly hypothetical closest common ancestor of the members of the group
  89. Polyphyletic
    group is one whose members' last common ancestor is not a member of the group.
  90. 5 steps preceded the origin of eukaryotic cells:
    1. Development of a flexible cell surface (loss of protective cell wall).

    2. Origin of a cytoskeleton through infolding of the cell membrane.

    3. Origin of a nuclear envelope as DNA attaches to the membrane of an infolded vesicle.

    4. Appearance of digestive vesicles or vacuoles.

    5. Acquisition of some organelles by endosymbiosis (e.g., mitochondria from a proteobacterium, chloroplasts from cyanobacteria).
  91. Primary endosymbiosis
    First, one eukaryote engulfed a cyanobacterium, gave rise to the first photosynthetic eukaryotes
  92. Secondary and tertiary endosymbiosis
    occurred multiple times; leading to other photosynthetic microbial eukaryote groups.
  93. Protozoans
    convenience term, protists formerly classified as animals; many are ingestive heterotrophs
  94. Algae
    convenience term, photosynthetic protists
  95. eukaryotes can be divided into five hypothesized clades
    Chromalveolates, Plantae, and some Excavates contain at least some photosynthetic species;

    Rhizaria and Unikonts do not.
  96. Chromalveolates:
    2 main groups: Alveolates and Stramenopiles

    •Include common groups of algae (Dinoflagellates, Diatoms) and “seaweeds” (Brown algae).

    Haptophytes are unicellular, marine, flagellates, mostly armored
  97. Alveolates
    • subgroup of Chromalveolates
    • synapomorphy = presence of alveoli (sacs beneath surface of plasma membrane )

    Broken into 3 groups: Apicomplexans, Dinoflagellates, Ciliates
  98. Apicomplexans
    subgroup of alveolates

    all parasites whose infectious stages have an apical complex of organelles that penetrate host cells
  99. Dinoflagellates
    subgroup of alveolates

    have 2 flagella that arise from grooves formed by internal cellulose plates. They are free-living and common in both freshwater and marine habitats. Responsible for toxic “red tides” and fishy odors; also endosymbionts in corals
  100. Ciliates
    subgroup of alveolates

    have two types of nuclei and use cilia (structure identical to flagella) for motility and feeding (e.g., Paramecium); they are heterotrophic. Some also have Trichocysts, like sharp darts on filament tip.
  101. Stramenopiles
    Synapomorphy are rows of tubular hairs on the longer of the two flagella.

    • Includes diatoms, brown algae, oomycetes, and
    • slime nets.
  102. Diatoms
    Subgroup of Stramenopiles

    •live in a petri-dish-like silica shell called a frustule; abundant primary producers in both freshwater and marine environments.

    •They are either bilaterally or radially symmetrical. Asexual reproduction is by binary fission. Both top and bottom of the “petri plate” become the tops of the new daughter cells.
  103. Brown algae
    Subgroup of Stramenopiles

    •multicelluar; some get very large, includes large seaweeds and kelps; mostly marine.

    •The carotenoid fucoxanthin imparts the brown color.

    •Sargassum forms dense mats in the Sargasso Sea in the mid-Atlantic.

    •Most brown algae attach to rocks by a holdfast that glues it to the rock. The “glue” is alginic acid—a gummy polymer of sugars. It is harvested and used as an emulsifier in ice cream, cosmetics, and other products.
  104. Oomycetes
    Subgroup of Stramenop•water molds and downy mildews, nonphotosynthetic. Diploid throughout most of their life cycle, have flagellated reproductive cells. Responsible for Irish potato famine.

    •Water molds are absorptive heterotrophs or saprobic (feed on dead organic matter)(e.g. Saprolegnia). Once were classed as fungi, but are now known to be unrelated.

    •Some are coenocytes- many nuclei enclosed in one plasma membrane.
  105. Plantae
    •Divided into 5 main groups, 4 of which are entirely aquatic or marine; the 5th group being the land plants.

    Glaucophytes, Red algae, Chlorophytes, Land Plants, Charophytes

    all chloroplasts trace back to a single incidence of endosymbiosis of a cyanobacterium
  106. Glaucophytes
    Subgroup of plantae

    unicellular, freshwater organisms. Likely first group to diverge. Chloroplasts retain bit of peptidoglycan, between inner and outer membrane, normally only in prokaryotes (e.g. cyanobacteria). Feature has been lost in other groups
  107. Red algae
    Subgroup of plantae

    •include multicellular marine forms that often accumulate large amounts of the red pigment phycoerythrin. Mucilaginous polysaccharides are source of agar.
  108. Chlorophytes, Charophytes and Land Plants
    Subgroups of plantae

    • Synapomorphies of the 3 groups include
    • chlorophyll a and b in chloroplasts, and have starch as a storage product
  109. Charophytes
    •are most closely related to higher plants.

    •More than 17,000 species; marine, freshwater, and terrestrial. Unicellular to large multicellular forms.

    •Some chlorophytes form colonies of cells that show the possible first step for cell and tissue differentiation. (e.g. Volvox colonies have cells for reproduction.
  110. Excavates
    several clades lack mitochondria—a derived condition (in the Diplomonads and Parabasalids).

    •All are single celled.

    •Non-photosynthetic except for some Euglenids.

    •Some groups are very important medically (e.g., Kinetoplastids); with several groups that cause human disease
  111. •Heteroloboseans
    have both amoeboid and flagellated life stages. Sometimes infect humans from under- chlorinated pool water.
  112. Diplomonads
    Trichomonas vaginalis is responsible for a sexually transmitted disease in humans.

    unicellular; lack mitochondria.
  113. parabasalids
    Subgroup of Excavates. unicellular; lack mitochondria.

    Trichomonas vaginalis is responsible for a sexually transmitted disease in humans.
  114. Euglenids
    include autotrophic and heterotrophic flagellates.

    •Have an anterior chamber from which 1 or 2 flagella emerge, typically free-living.

    •Some species with chloroplasts, others without; some species produce them only when needed.
  115. Kinetoplastids
    •unicellular parasites with two flagella and a single mitochondrion.

    •They have a single large mitochondrion associated with a kinetoplast, a unique organelle that houses extranuclear circular DNA and proteins.

    •All are symbiotic and some are pathogenic to their hosts.

    •Trypanosomes are kinetoplastids; including African Sleeping Sickness (caused by T. brucei), Chagas’ disease (caused by T. cruzi), and Leishmaniasis (caused by Leishmania). They can change their cell surface molecules frequently, making them diffucult to control.
  116. Rhizaria
    3 subgroups: Cercozoans, Foraminiferans, Radiolarians

    Unicellular, aquatic, amoeboid and use long thin pseudopodia for locomotion.
  117. Cercozoans
    Subgroup of Rhizaria

    •Diverse with some amoeboid and some flagellated forms; found in freshwater and soil.

    •One group has chloroplasts derived from a green alga by secondary endosymbiosis.
  118. Foraminiferans
    Subgroup of Rhizaria

    •Foraminiferans- secrete shells of calcium carbonate.

    •Feed and move with thread-like branched pseudopods extending through numerous pores in the shell; form sticky net capturing smaller plankton.

    •All marine; some plankton, some benthic, 90% spp. known from fossils.

    •Responsible for calcium deposits such as the “white cliffs of Dover.”
  119. Radiolarians
    Subgroup of Rhizaria

    •Secrete a glassy internal endoskeleton that can be remarkably ornate; among the most beautiful of all microbial eukaryotes.

    •Exclusively marine.

    •Have thin, stiff pseudopods reinforced by microtubules; pseudopods increase surface area for exchange of materials; and help them float.
  120. Unikonts
    fungi and animals, have single flagellum (if present)

    2 subgroups: Opisthokonts and Amoebozoans
  121. Opisthokonts
    Subgroup of Unikonts

    posterior flagellum (e.g. human sperm)

    –Includes Fungi, Choanoflagellates, and Animals
  122. Amoebozoans
    subgroup of Unikonts

    amoeboid in form, lobe-shaped pseudopods
  123. Loboseans
    Subgroup of Amoebozoans

    unicellular, cells live independently, do not aggregate. Includes Entamoeba histolytica, responsible for amoebic dysentery and amoebic liver abscess in humans.
  124. Slimemolds
    Subgroup of Amoebozoans

    All are motile by “cytoplasmic streaming”, ingest food by endocytosis, and form spores on stalks called fruiting bodies. Slime molds are found in cool, moist habitats, primarily forests.
  125. Animals and fungi arose from a common ancestor within the ___________ clade
    Opisthokont
  126. Multicellular life probably evolved from stalked colonial forms such as this ______. They resemble a type of cell found in sponges.

    Therefore, ________ may represent a connection between unicellular and multicellular animals
    choanoflagellate
  127. One synapomorphy in land plants
    development from an embryo protected by tissues from the parent plant; called the embryophytes.
  128. The derived features that the land plants share with green algae (the Chloropohytes and Charophytes) include
    Chlorophyll a and b.

    Starch as a storage product.

    Cellulose in cell walls.
  129. Green plants vs Streptophytes (image)
  130. Green plants vs Streptophytes (Definition)
    • Green plants: Streptophytes plus
    • Chlorophytes,
    • ---synapomorphy= chlorophyll b, starch

    • •Streptophytes = land plants and closely related green algae (Charophytes),
    • ---synapomorphy= all retain egg within the parent body
  131. Coleochaetales (a Charophyte, incl Coleochaete scutata)
    shows strong morphological similarities to land plants such as flattened form.
  132. •Charales (group in Charophytes, incl. Chara spp.)
    • is mostclosely related to landplants.
    • Synapomorphy = branchedapical growth, plasmodesmatajoining cytoplasm of adjacent cells.
  133. Land Plants: Current classification into __ major clades
    10:

    • Nonvascular plants: Hepatophyta, anthocerophyta, bryophyta
    • Vascular plants: 2 non seed, 4 gymnosperms, angiosperms
  134. Nonvascular plants
    liverworts, hornworts, and mosses
  135. Vascular plants
    7 groups which form a clade, all have conducting cells called tracheids

    •Nearly 90% of living plant species are Angiosperms (flowering plants).
  136. Plants first appeared on land _________ years ago
    400–500 million
  137. 7 Characteristics of plant adaptation to life on land
    -Cuticle- waxy covering prevents drying.

    -Stomata—openings in stems and leaves; regulate gas exchange (except liverworts)

    -Gametangia enclosing gametes to prevent desiccation.

    -Embryos (young sporophyte) enclosed within protective structure.

    -Pigments that protect against UV radiation.

    -Thick spore walls (w/ sporopollenin) to prevent drying.

    -Mutualistic relationships with a clade of fungi (called glomeromycetes) that allow nutrient uptake from soils.
  138. alternation of generations.
    •Includes multicellular diploid (sporophyte) and multicellular haploid (gametophyte) individuals.

    •Gametes produced by mitosis unite to form a zygote.

    •The transitions between the generations occur at fertilization (to diploid sporophyte) and meiosis (to haploid gametophyte).
  139. female vs male plant
    archegonium vs antheridium
  140. __________ is a major theme as plants evolve in complexity
    Reduction of the gametophyte generation
  141. For __% of the Earth’s history the land was barren, totally uninhabited by life.
    90
  142. •Land plants probably evolved from______ about _____ during the ___________ of the Paleozoic era.
    Charophytes/500 mya/Ordovician period
  143. Primitive vascular plants appear in the fossil record about ____ in the_______.
    450 mya/Silurian
  144. Rhyniophytes
    (in Silurian) were the earliest vascular plants (now extinct) had dichotomous branching, but lacked leaves and roots

    They were anchored by rhizomes (horizontal portions of stem) and rhizoids (water-absorbing filaments)
  145. •Lycophytes (club mosses) also appeared in the_____. Monilophytes (ferns and fern allies) appeared in the______.
    Silurian, Devonian

    -These groups had true roots and leaves, and two types of spores.
  146. Euphyllophytes.
    Clade of monilophytes and seed plants

    • Synapomorphy includes overtopping growth
    • - new branches grow beyond the others; an advantage in the competition for light.
  147. Two types of leaves:
    Microphylls: small, simple leaves, usually one vascular strand. [Club mosses (lycophytes)]

    Megaphylls: larger and more complex
  148. Homosporous
    Life cycle of the most ancient vascular plants- a single type of spore

    •produce one type of gametophyte that has both archegonium and antheridium.
  149. Heterosporous
  150. Nontracheophytes
    first successful colonizers of land
  151. Hepatophytes
    •Liverworts: 9,000 species.

    sporophyte grows from bottom, very short (few mm); no filamentous stage, lie flat.

    Some have leafy gametophytes; some have thalloid gametophytes.

    A stalk raises the simple sporangium above ground level to allow spores to be dispersed.

    Liverworts also reproduce asexually:

    By simple fragmentation of the gametophyte;

    And by gemmae—lens-shaped clumps of cells in gemmae cups. Gemmae are dispersed by raindrops
  152. The Bryophytes
    •Mosses: 15,000 species.

    •Mosses (plus hornworts and vascular plants) have stomata, important in water and gas exchange.

    •Mosses are among the most common plants in northern climates (cover ~3% of land surface).

    •Some species of bryophytes have water conducting tissues (hydroids, progenitors of tracheids), but they don’t have lignin. Maximum height ~ 50 cm (20 in).

    •Moss sporophytes (like vascular plants) grow by apical cell division- a region at the growing tip provides an organized pattern of division, elongation, and differentiation.

    •Sphagnum grows in swampy places; upper layers of moss compress lower layers that are beginning to decompose, forming peat; leads to formation of coal.
  153. Anthocerophyta
    Hornworts: 100 species.

    •Hornworts have simple gametophyte; which are flat plates of cells.

    •Two characters distinguish Hornworts from Liverworts AND Mosses:

    1. Hornwort cells have a single, large chloroplast.

    2. The sporophyte grows from bottom and has no stalk; but has a basal region capable of infinite cell division. Sporophytes can grow up to 20 cm.

    •Hornworts have internal cavities filled with nitrogen-fixing cyanobacteria.

    The exact evolutionary position of the hornworts is still unclear; sometimes the sister group to the mosses plus the vascular plants (the two groups that express apical cell division)
  154. Seedless Vascular Plants (Nonseed Tracheophytes)
    •Must have water for at least one part of the life cycle- for the flagellated, swimming sperm.

    •Living phyla:

    -Club mosses (Lycophyta) – primitive leaves (Microphylls).

    Pteridophytes (Pteridophyta) – complex leaves (Megaphylls); include ferns (~12,000 living species), horsetails (15 species), whisk ferns (15 species)
  155. Lycophytes
    the club mosses, spike mosses, and quillworts: 1,200 species.

    •Roots and stems have dichotomous branching; leaves are microphylls.

    •Some club mosses have sporangia arranged in clusters called strobili.

    •Others have sporangia on upper leaf surfaces—sporophylls.

    •Lycophytes were dominant during the Carboniferous period.

    •One type of coal- cannel coal- is formed almost entirely from the spores of a tree lycophyte Lepidodendron.
  156. Monilophytes
    • horsetails, whisk ferns, and most ferns, form a clade
    • --Horsetails and whisk ferns are monophyletic, ferns are not

    •growth is overtopping.
  157. Horsetails
    Monilophyte,

    Fifteen species in one genus—Equisetum.

    Silica in cell walls—“scouring rushes.”

    Have true roots; sporangia are on short stalks called sporangiophore.

    Leaves are reduced megaphylls in whorls. Each stem segment grows from the base.
  158. Whisk ferns
    •Whisk ferns: Fifteen species in two genera.

    •No roots, but well-developed vascular system.

    •Psilotum sp. has scales instead of leaves.

    •Whisk ferns were once thought to be descendents of rhyniophytes.

    •DNA analysis determined a more modern origin. Evolved from more complex ancestors by reduction or loss of megaphylls and true roots.
  159. Leptosporangiate ferns
    12,000 species. Most ferns (97%) belong to this clade.

    •Sporangia walls are only one cell thick, borne on a stalk.

    •Sporophytes have true roots, stems, and leaves.

    •Fern leaf starts development as a coiled “fiddlehead.”

    •Independent gametophyte generation restricts habitats available to ferns. Most ferns are in shaded, moist environments because water is required for swimming sperm.

    •Tree ferns can reach heights of 20 m.

    •DNA research suggests that diversification of modern ferns is fairly recent.

    •Ferns may have taken advantage of shady environments created by angiosperm trees.
  160. Fern life cycle
    •Spore mother cells in sporangia form haploid spores by meiosis.

    •Spores can be blown by wind and develop into gametophyte far from parent plant.

    •Fern gametophytes produce antheridia and archegonia, not always at the same time or on the same gametophyte.

    •Sperm swim through water to archegonium to fertilize egg.

    •Zygote develops into independent sporophyte.

    •Sporangia occur on undersides of leaves in clusters called sori.
  161. •Late in the ______, some plants developed secondary
    growth: ___________________.
    Devonian (~400 mya)

    thickened woody stems of xylem
  162. Alternation of generations differs between nonvascular plants, vascular non-seed plants, and seed plants
  163. The evolution of seeds provided a means for plants to:
    Tolerate severe ecological conditions that could not support an independent gametophyte stage.

    Withstand variation in climate that included unfavorable periods of drought or cold.

    Develop mechanisms for both animal and wind dispersal into new habitats
  164. Seed plants dominate on land during the___a___ era

    Gymnosperms were dominant during the ___a___, until about ______.

    Angiosperms also appear later in the ___a___
    era during the ________ period (oldest fossils from _____)

    Angiosperm radiation was explosive; they became dominant in _____ in the_______ era.
    • a)Mesozoic
    • 65 Mya
    • Cretaceous/140 mya
    • ~60 million yrs/Cenozoic [remain dominant plants]
  165. Factors that contributed to the success of seed plants include:
    • -reduction of the size of thegametophyte
    • -seeds
    • -Pollen
  166. heterosporous
    produce 2 types of spores (seed plants do this)

    One becomes female gametophyte, one becomes male gametophyte.
  167. Megagametophyte
    • The female gametophyte that arises from a megaspore of a heterosporous plant.
  168. Megasporangium
    • A plant structure in which megaspores are formed, such as those of the female cones of pines
  169. Pollination
    when a pollen grain lands near a female gametophyte and a pollen tube is produced that digests its way through the sporophyte tissue to the megagametophyte.
  170. Gymnosperms
    (“naked seeds”): ovules and seeds are not protected by ovary or fruit tissue

    • •4 major groups of living Gymnosperms
    • §Cycads (Cycadophyta): 300 spp,
    • §Ginkgos (Ginkgophyta): only 1 species survives
    • §Gnetophytes (Gnetophyta): 90 spp.
    • §Conifers (Coniferophyta): 700 spp.,
  171. Cycads (Cycadophyta):
    300 spp, appear palm-like, but w/o flowers; mostly tropical.
  172. Ginkgos (Ginkgophyta):
    §Ginkgos (Ginkgophyta): only 1 species survives, Ginkgo biloba.
  173. Gnetophytes (Gnetophyta):
    90 spp., restricted to deserts and the tropics.
  174. Conifers (Coniferophyta):
    700 spp., the cone bearers, includes the pines, firs, junipers; aredominant trees in northern climates; include oldest living organisms on earth(e.g. bristlecone pines that germinated ~4,800 ya).
  175. Cone vs Strobilus
    A cone is a modified stem, bearing a tight cluster of scales (reduced branches), specialized for reproduction. Megaspores are produced here.

    • Strobilus:
    • cone-like structure; scales are modified leaves. Microspores are produced here.
  176. The oldest angiosperm fossils are_______, ______ old. Radiation was explosive during the Tertiary. Over _______ species exist today.
    Jurassic, 150 million years

    • Tertiary
    • 250,000
  177. 5 Synapomorphies in Angiosperms include:
    Double fertilization with a diploid zygote and triploid endosperm.

    Endosperm—nutritive tissue in seeds

    Ovules and seeds enclosed in a carpel

    Flower develops as a reproductive structure

    Fruits (mature ovary) protects ovule and aid in dispersal.

    • Xylem with vessel elements and fibers, phloem with
    • companion cells
  178. Double fertilization
    -Microgametophyte has two male gametes. Nucleus of one combines with egg.

    -The other nucleus combines with two haploid nuclei of female gametophyte to form a triploid nucleus—becomes the endosperm.

    -Endosperm nourishes developing sporophyte.
  179. Carpels
    •Enclose ovules and seeds; that’s why Angiosperms mean “enclosed seed”:

    -provide protection, and may interact with pollen to prevent self-pollination.
  180. Anther, Carpel, Filament, Ovary, Ovule, Petal, Receptacle, Sepal, Stamen, Stigma, Style
  181. Stamens bear______: consist of ____and_____.

    Carpels bear______. One or more carpels form the_____ = _______.

    Petals and sepals are modified leaves. Often play a role in attracting pollinators.
    microsporangia/filament and anther

    megasporangia/ pistil/stigma, style, ovary
  182. basal clades
    •have large and variable # of sepals and petals.
  183. Monoecious plant:
    “one-housed”; male and female flowers occur on the same plant.
  184. •Dioecious plant:
    “two-housed”;male and female flowers on different plants. Inflorescence: grouping offlowers.
  185. Angiosperms are _____sporous
    Hetero
  186. •_______ fruits develop from one carpel (e.g. cherry).

    •_______ fruits develop from several carpels (e.g. rasberry).

    •_______ fruits form from a cluster of flowers (e.g. pineapple).

    •_______ fruits develop from parts other than carpels (strawberry, apple).
    Simple/Aggregate/Multiple/Accessory
  187. Most Angiosperms are in two clades:
    Monocots and Eudicots
  188. Monocots:
    one cotyledon (generally have leaves with parallel veins ); mostly wind pollinated. Monocots include grasses, cattails, lilies, orchids, and palms
  189. Eudicots:
    two cotyledons (usually have leaves with netlike veins); mostly animal pollinated (e.g. most flowering plant species). Eudicots include most of the seed plants, including most herbs (nonwoody plants), vines, trees, and shrubs.
  190. Other 4 Angiosperm clades include:
    Amborella trichopoda: the most primitive living angiosperm (found only on New Caledonia, an island in the south pacific).

    “Water lilies”: the most primitive of the widely distributed Angiosperm groups.

    Star anise (Illicium floridanum) and relatives.

    Magnoliids (Magnolias).
  191. __________, fungi, and_______ form a clade—the ______
    Choanoflagellates/animals/opisthokonts
  192. Fungi synapomorphies:
    •Absorptive heterotrophy

    •Chitin in cell walls
  193. absorptive heterotrophy
    Fungi's method of obtaining nutrients

    Secrete digestive extracellular enzymes that digest food outside the body, then smaller molecules are moved across cell walls
  194. Saprobes
    carbon and nutrients directly from dead organic matter.
  195. Parasites
    Absorb nutrients from living hosts
  196. Mutualists
    Both partners benefit
  197. Predatory Fungi
    • secrete sticky substances so that passing organisms stick tightly to them and hyphae then quickly invade the prey.

    some soil fungi make a constricting ring that can trap nematodes
  198. hyphae
    Minute threads in multicellular fungi, form an interwoven mat called mycelium
  199. Separate Hyphae
    cells of hyphae are separated by incomplete cross walls or septa with pores that permit organelles to move between cells.
  200. Coenocytic Hyphae
    lack septa – multiple nuclei are located within one cytoplasmic mass.
  201. Most parasitic fungi have haustoria
    haustoria are nutrient absorbing hyphal tips that press into host cells without breaking through the plasma membranes
  202. Saprobic fungi
    Major decomposers on Earth

    §Without fungal decomposers, Earth’s carbon cycle would fail; carbon would be buried.

    §Saprobic fungi return C to the atmosphere as respiratory CO2, available for photosynthesis by plants.

    §Contribute to soil formation and recycling nutrient elements
  203. Lichen
    Mutualistic relationship between fungi and photosynthetic organism
  204. Mycorrhizae

    1) Ectomycorrhizae

    2) Arbuscular mycorrhizae
    Fungi+plant roots

    • 1) Fungi wrap around root
    • 2) Fungi penetrate cell walls of root but not plasma membrane
  205. Asexual reproduction in Fungi
    •Production of haploid spore within sporangia.

    •Production of naked spores at tips of hyphae called conidia.

    •Cell division by unicellular fungi- fission (equal division) or budding (unequal).

    •Breakage of the mycelium.
  206. Plasmogamy
    When hyphae of differing mating types fuse but not nuclei
  207. dikaryotic stage
    •2 genetically different haploid nuclei coexist within same hyphae.

    -Hyphae is neither haploid or diploid, rather it is dikaryotic (n+n)
  208. Karyogamy
    Fusion of the nuclei
  209. •Of the six major groups of fungi, the ______ and _______ fungi are not monophyletic groups, but
    are paraphyletic; they are convenient categories for a general introduction to the fungi.
    Chytrids and Zygospore
  210. 6 major groups of fungi
    Chytrids, Zygospores, Basiomycota, Ascomycota, Microsporidia, Glomeromycota
  211. Dikarya
    Monophyletic group of Basiomycota and Ascomycota
  212. Microsporidia
    •unicellular fungi, obligate intracellular parasites of animals; 1,500 species.

    •They are among the smallest eukaryotes known.

    • •The host cell is penetrated by a polar tube of the microsporidian spore, and the contents of the
    • spore are injected into the host.

    • •The sporoplasm replicates in the host cell and
    • produces new infective spores.

    •The life cycle of some species is complex and involves multiple hosts.

    • •Microsporidia have cell walls with chitin, and
    • lack true mitochondria; they have reduced structures called mitosomes.

    •DNA sequencing indicates they are highly reduced, parasitic fungi, but exact placement is still debated.
  213. Chytrids
    aquatic fungi, were once classed as protists but have chitin in their cell walls.

    •Have flagellated gametes, some show alternation of generations (like plants), no dikaryon phase

    •Multicellular diploid stage includes a structure that can withstand freezing and drying.

    •Chytrids may be parasitic or saprobic; some are found in foregut-fermenting animals such as cattle and deer.

    •Some chytrids are unicellular, others have rhizoids, still others are coenocytic.
  214. Chytridiomycosis
    Infectuous disease killing amphibians throughout the world, killed ~30%, no effective measure for controlling the disease
  215. Zygospores
    •conjugating fungi”

    •Terrestrial fungi- saprobes on soils, parasites of insects and spiders, as mutualists with other fungi and invertebrates.

    •Zygote is the only diploid cell

    •Hyphae are coenocytic (lack septa)

    •Stalked sporangiophores contain sporangia

    •>1000 species described; includes Rhizopus stolonifer, black bread mold.
  216. Glomeromycota
    • Arbuscular mycorrhizae fungi
    • Coenocytic hyphae
    • Reproduce asexually
  217. Ascomycota
    • Sac fungi
    • produce asci: sacs which contain sexually produced haploid ascospores

    Filamentous sac fungi reproduce asexually by conidia that form at the tips of hyphae

    Sexual reproduction includes a brief dikaryon
  218. Ascomycetes (2 groups)
    1) Euascomycetes “true”: asci in a fruiting body called an ascocarp.

    -“Cup fungi,” includes morels and truffles

    -Molds, including Aspergillus and Penicillium

    -Ergot—parasite on rye

    -Mildews

    -Parasites on plants such as chestnut blight and Dutch elm disease

    2) Hemiascomycetes “half”: no ascocarp

    -Most are unicellular—yeasts

    -Baker’s/Brewer’s yeast Saccharomyces cerevisiae
  219. Basidiomycetes
    the “club fungi”

    •Fruiting structures are basidiomata

    •30,000 species, includes edible mushrooms, puff balls, bracket fungi

    •Hyphae have septa with pores.

    •The basidia are the characteristic sexual reproductive structures; site of nuclear fusion.

    • •In mushrooms, basidia form on specialized structures
    • called gills or pores.

    • •The dikaryon stage may persist for years—some
    • live decades or even centuries.

    •Also include plant pathogens such as rusts and smuts infect cereal grains. Other club fungi species are fungal partners in ectomycorrhizae.
  220. Reproductive Characteristics:

    Microsporidia

    Chytridiomycota
    • Microsporidia = unicellular fungi, 1500 spp.
    • •obligate intracellular parasites of animals
    • •They are among the smallest eukaryotes known.

    • Chytridiomycota = Chytrids, ~1000 spp.
    • §Motile zoospores with flagella.
    • §Mostly aquatic, once considered protists
  221. Reproductive Characteristics:

    Zygomycota

    Glomeromycota
    • Zygomycota =Zygote fungi, >1000 spp.
    • §Resistant zygosporangium as sexual stage.
    • §mostly live in soil

    • Glomeromycota = arbuscular mycorrhizal (AM) fungi, <200 spp.
    • •Reproduce asexually.
    • •Associate with plant roots.
    • •Live on roots in soil
  222. Reproductive Characteristics:

    Ascomycota

    Basidiomycota
    • Ascomycota= Sac fungi, ~64,000 spp.
    • •Sexual spores borne internally in sacs called asci.
    • •includes truffles, morels, lichens, some yeasts; some are pathogenic

    • Basidiomycota = Club fungi, ~30,000 spp.
    • •Sexual spores borne externally on club-shaped structures called basidia.
    • •includes mushrooms, rusts, shelf fungi, puffballs, lichens, some yeasts
  223. Mold
    a rapidly growing, asexually reproducing fungus. Molds are used in the production of antibiotics and cheese. Many molds are classified as “imperfect fungi” because on asexual reproduction is known.
  224. Yeasts
    Unicellular members of the zygomycetes, ascomycetes, and basidiomycetes.The term does not refer to a single taxonomic group but rather to a lifestyle that has evolved multiple times.
  225. Lichens
    Found in both Ascomycetes and Basidiomycetes. About 15,000 lichen “species” have been described.

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