Bio 182 chp 27-31

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1

Chapter 27 – Bacteria and Archaea

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2

• Expected knowledge from Microbiology; see Section 27.1 to review this material.

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3

o Compare the cell wall structure of gram-positive bacteria and gram-negative bacteria. Be able to relate this to the gram staining procedure.

Gram-negative Cells
The cell walls of Gram-negative bacteria are more chemically complex, thinner and less compact.

4

o Explain how antibiotic effectiveness correlates with bacterial cell wall structure. What role do R plasmids have in antibiotic resistance?

Antibiotics target peptidoglycan to tear apart a bacteria. Gram negative bacterial cells have a higher resistance to antibiotics because of that fact.
R-plasmids: Contain resistant enzymes that can be transferred through conjugation to resist antibiotics

5

o Know the three different shapes of bacteria.

Bacillis (rod), Spirilla (spiral), Cocci (circular)

6

o What is an endospore and why do they form?

Endospores form to live in extreme environments in order to survive in harsh conditions for centuries

7

o Define these prokaryotic structures: capsule, fimbriae, pili, flagella, plasmid, nucleoid, and heterocyst.

Capsule: sticky layer of polysaccharide or protein that can help cell adherence and/or evasion of a host's immune system
Fimbriae: Helps to stick to other individuals within their colony
Pili: longer than fimbriae and allow prokaryotes to exchange DNA
Flagella: aids in cell movement
Plasmid: small rings of DNA
Nucleoid: Region in cytoplasm that is not encased by a membrane
Heterocyst: carry out nitrogen fixation

8

• Review in Section 27.2 (previous knowledge) the genetic recombination processes of transformation, transduction, and conjugation that occur in prokaryotic organisms.

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9

• Know the four major modes of nutrition for prokaryotes as well as the role of oxygen in metabolism.

  • Photoautotrophy
  • Chemoautotrophy
  • Photoheterotrophy
  • Chemoheterotrophy
  • The Role of Oxygen in Metabolism
  • Prokaryotic metabolism varies with respect to O
  •  Obligate aerobes require O for respiration
  •  Obligate anaerobes are poisoned by O and use fermentation or anaerobic respiration
  •  Facultative anaerobes can survive with or without O
10

• Specify the impact of nitrogen fixing prokaryotes.

  • In nitrogen fixation, some prokaryotes convert atmospheric nitrogen (N2) to ammonia (NH3)
  • Which is good for plats
11

• Characterize (gram stain, nutritional mode, unique features, and an example) the major groups of bacteria: Proteobacteria (five subgroups), chlamydias, spirochetes, cyanobacteria, mycoplasmas, and gram-positives.

  • Chlamydias
    •  These bacteria are parasites that live within animal cells
    •  Chlamydia trachomatis causes blindness and nongonococcal urethritis by sexual transmission
  • Spirochetes
    •  Some are parasites, including Treponema pallidum, which causes syphilis, and Borrelia burgdorferi, which causes Lyme disease
    •  These bacteria are helical heterotrophs
  • Cyanobacteria
    •  These are photoautotrophs that generate O2
    •  Plant chloroplasts likely evolved from cyanobacteria by the process of endosymbiosis
  • Gram-Positive Bacteria
    •  Gram-positive bacteria include
      •  Actinomycetes, which decompose soil
      •  Bacillus anthracis, the cause of anthrax
      •  Clostridium botulinum, the cause of botulism
      •  Some Staphylococcus and Streptococcus, which can be pathogenic
      •  Mycoplasms, the smallest known cells
12

• Know some of the "extreme" conditions where Archaea members can be found and their general structure.

  • Halophiles
    • Salty
  • Thermophiles
    • Hot
  • Acidaphiles
    • High pH
  • Methangogens
    • Methane
13

• Explain the role of prokaryotes in chemical recycling and ecological interactions.

  • Chemical Recycling
    •  Prokaryotes play a major role in the recycling of chemical elements between the living and nonliving components of ecosystems
    •  Chemoheterotrophic prokaryotes function as decomposers, breaking down dead organisms and waste products
    •  Prokaryotes can sometimes increase the availability of nitrogen, phosphorus, and potassium for plant growth Prokaryotes can also “immobilize” or decrease the availability of nutrients
  • Ecological Interactions
    •  Symbiosis is an ecological relationship in which two species live in close contact: a larger host and smaller symbiont
    •  Prokaryotes often form symbiotic relationships with larger organisms
14

• Differentiate between mutualistic and pathogenic bacteria.

  •  Parasites that cause disease are called pathogens
  •  In mutualism, both symbiotic organisms benefit
  •  In commensalism, one organism benefits while neither harming nor helping the other in any significant way
  •  In parasitism, an organism called a parasite harms but does not kill its host
15

Chapter 28 – Protists

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16

• Know the nutritional modes that protists use to meet their nutritional needs.

  • Photoautotrophs, which contain chloroplasts
  • Heterotrophs, which absorb organic molecules or ingest larger food particles
  • Mixotrophs, which combine photosynthesis and heterotrophic nutrition
17

• Define contractile vacuole and explain its role for a protist.

  • Maintains osmotic pressure
18

• Specify how the process of endosymbiosis could explain the diversity seen in protists.

  • The abundant diversity of prokaryotes originated from the process of endosymbiosis, whereby a unicellular protist engulfs another unicellular organism. The consumed organism then becomes an endosymbiont, and eventually transforms into an organelle, such as a mitochondrion. Additionally, red and green algae themselves become endosymbiotic in a process known as secondary endosymbiosis, forming plastids in modern photosynthetic eukaryotes.
19

• Characterize (life/reproduction cycle, nutritional mode, unique structural features, and examples when provided in the text) the following groups of organisms:

...

20

o Excavates (diplomonads, parabasalids, euglenozoans)

  • Diplomonads
    •  Have reduced mitochondria called mitosomes
    •  Derive energy from anaerobic biochemical
    • pathways
    •  Have two equal-sized nuclei and multiple flagella
    •  Are often parasites, for example, Giardia intestinalis
  • Euglenozoans
    •  Euglenozoa is a diverse clade that includes
    • predatory heterotrophs, photosynthetic autotrophs,
    • mixotrophs, and parasites
    •  The main feature distinguishing them as a clade is
    • a spiral or crystalline rod inside their flagella
    •  This clade includes the kinetoplastids and
    • euglenids
21

o Stramenopiles (diatoms, golden algae, brown algae)

  • Diatoms are unicellular algae with a unique two-part, glass-like wall of silicon dioxide
    • Diatoms are a major component of phytoplankton and are highly diverse
    •  Fossilized diatom walls compose much of the sediments known as diatomaceous earth
    •  After a diatom population has bloomed, many dead individuals fall to the ocean floor undecomposed
  • Brown Algae
    •  Brown algae are the largest and most complex
    • algae
    •  All are multicellular, and most are marine
    •  Brown algae include many species commonly
    • called “seaweeds”
    • © 2014 Pearson Education, Inc.
    •  Giant seaweeds called kelps live in deep parts of
    • the ocean
    •  Brown algal seaweeds have plantlike structures:
    • the rootlike holdfast, which anchors the alga, and
    • a stemlike stipe, which supports the leaflike
    • blades
    •  Similarities between algae and plants are
    • examples of analogous structures
22
  • Alternation of Generations
  • Alternation of Generations
    •  A variety of life cycles have evolved among the
    • multicellular algae
    •  The most complex life cycles include an
    • alternation of generations, the alternation of
    • multicellular haploid and diploid forms
    •  Heteromorphic generations are structurally
    • different, while isomorphic generations look
    • similar
    •  The diploid sporophyte produces haploid
    • flagellated spores called zoospores
    •  The zoospores develop into haploid male and
    • female gametophytes, which produce gametes
    •  Fertilization of gamates results in a diploid zygote,
    • which grows into a new sporophyte
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o Alveolates (dinoflagellates, apicomplexans, ciliates)

  • Members of the clade Alveolata have membrane-enclosed sacs (alveoli) just under the plasm membrane
  •  The alveolates include
    • Dinoflagellates
      • Dinoflagellates have two flagella and each cell is reinforced by cellulose plates
        •  They are abundant components of both marine and freshwater phytoplankton
        •  They are a diverse group of aquatic phototrophs, mixotrophs, and heterotrophs
        •  Toxic “red tides” are caused by dinoflagellate blooms
      • Apicomplexans
        • Apicomplexans are parasites of animals, and some cause serious human diseases
          •  They spread through their host as infectious cells called sporozoites
          •  One end, the apex, contains a complex of organelles specialized for penetrating host cells and tissues
          •  Most have sexual and asexual stages that require two or more different host species for completion
        • Ciliates
          • Ciliates, a large varied group of protists, are named for their use of cilia to move and feed
          •  They have large macronuclei and small micronuclei
          •  Genetic variation results from conjugation, in which two individuals exchange haploid micronuclei
          •  Conjugation is a sexual process, and is separate from reproduction, which generally occurs by binary fission
24

o Rhizarians (forams, cercozoans, radiolarians)

  • Many species in the rhizarian clade are amoebas
  •  Amoebas are protists that move and feed by pseudopodia, extensions of the cell surface
  •  Rhizarian amoebas differ from amoebas in other clades by having threadlike pseudopodia
  •  Rhizarians include radiolarians, forams, and Cercozoans
    • Radiolarians
      • Marine protists called radiolarians have delicate, symmetrical internal skeletons that are usually made of silica
      •  Radiolarians use their pseudopodia to engulf microorganisms through phagocytosis
      •  The pseudopodia of radiolarians radiate from the central body
    • Forams
      • Foraminiferans, or forams, are named for porous, generally multichambered shells, called tests
      •  Pseudopodia extend through the pores in the test
      •  Many forams have endosymbiotic algae
      •  Foram tests in marine sediments form an extensive fossil record
      •  Researchers can use measures of the magnesium content in fossilized forams to estimate changes in ocean temperature over time
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o Archaeplastida (red algae, green algae)

  •  Archaeplastida is the supergroup that includes
  • red algae, green algae, and land plants
  •  Plastids arose when a heterotrophic protist acquired a cyanobacterial endosymbiont
  •  The photosynthetic descendants of this ancient protist evolved into red algae and green algae
  •  Land plants are descended from the green algae
  • Green Algae
    •  Green algae are named for their grass-green chloroplasts
    •  Plants are descended from the green algae
    •  Green algae are a paraphyletic group
    •  The two main groups are the charophytes and the chlorophytes
    •  Charophytes are most closely related to land plants
    •  Most chlorophytes live in fresh water, although many are marine
    •  Other chlorophytes live in damp soil, as symbionts in lichens, or in environments exposed to intense visible and ultraviolet radiation
26

o Unikonts (slime molds – plasmodial and cellular, tubulicid, Entamoeba)

  • Slime Molds
    •  Slime molds, or mycetozoans, were once thought to be fungi
    •  DNA sequence analyses indicate that the resemblance between slime molds and fungi is a result of convergent evolution
    •  Slime molds include two lineages, plasmodial slime molds and cellular slime molds
  • Plasmodial Slime Molds
    •  Many species of plasmodial slime molds are brightly pigmented, usually yellow or orange At one point in the life cycle, plasmodial slime
    • molds form a mass called a plasmodium (not to be
    • confused with malarial Plasmodium)
    •  The plasmodium is not multicellular
    •  It is undivided by plasma membranes and contains
    • many diploid nuclei
    •  It extends pseudopodia through decomposing
    • material, engulfing food by phagocytosis
  • Cellular Slime Molds
    •  Cellular slime molds form multicellular aggregates in which cells are separated by their membranes
    •  Cells feed individually but can aggregate to
    • migrate and form a fruiting body
    •  Dictyostelium discoideum is an experimental model for studying the evolution of multicellularity

Entamoebas
 Entamoebas are parasites of vertebrates and
some invertebrates
 Entamoeba histolytica causes amebic dysentery,
the third-leading cause of human death due to
eukaryotic parasites

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• Understand the various roles that protists play in ecological communities.

 These populations can explode when limiting
nutrients are added
 Many protists are important producers that obtain
energy from the sun
 In aquatic environments, photosynthetic protists
and prokaryotes are the main producers
 In aquatic environments, photosynthetic protists
are limited by nutrients

28

Chapter 31 – Fungi

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29

• Describe the structural and nutritional features of fungi.

  • Nutrition and Ecology
    •  Fungi are heterotrophs and absorb nutrients from
    • outside of their bodies
    •  Fungi use enzymes to break down a large variety
    • of complex molecules into smaller organic
    • compounds
    •  The versatility of these enzymes contributes to
    • fungi ’s ecological success
  • Body Structure
    •  The most common body structures are
    • multicellular filaments and single cells (yeasts)
    •  Some species grow as either filaments or yeasts;
    • others grow as both
    •  The morphology of multicellular fungi enhances
    • their ability to absorb nutrients
    •  Fungi consist of mycelia, networks of branched
    • hyphae adapted for absorption
    •  A mycelium ’s structure maximizes its surface-to-
    • volume ratio
    •  Fungal cell walls contain chitin
    •  Coenocytic fungi lack septa and have a
    • continuous cytoplasmic mass with hundreds or
    • thousands of nuclei
    • Most fungi have hyphae divided into cells by
    • septa, with pores allowing cell-to-cell movement of
    • organelles
30

• Know the role of hyphae (coenocytic and septate) in mycorrhizal associations.

  • Specialized Hyphae in Mycorrhizal Fungi
    •  Some unique fungi have specialized hyphae called
    • haustoria that allow them to penetrate the tissues
    • of their host
    • Mycorrhizae are mutually beneficial relationships
    • between fungi and plant roots
    •  Ectomycorrhizal fungi form sheaths of hyphae
    • over a root and also grow into the extracellular
    • spaces of the root cortex
    •  Arbuscular mycorrhizal fungi extend hyphae
    • through the cell walls of root cells and into tubes
    • formed by invagination of the root cell membrane
    •  Mycorrhizal fungi deliver phosphate ions and
    • minerals to plants
    •  Most vascular plants have mycorrhizae
    •  Mycorrhizal fungi colonize soils by the dispersal of
    • haploid cells called spores
31

• Explain the asexual and sexual methods by which spores are produced.

  • Sexual Reproduction
    •  Fungal nuclei are normally haploid, with the
    • exception of transient diploid stages formed during
    • the sexual life cycles
    •  Sexual reproduction requires the fusion of hyphae
    • from different mating types
    •  Fungi use sexual signaling molecules called
    • pheromones to communicate their mating type
    •  Plasmogamy is the union of cytoplasm from two
    • parent mycelia
    •  In most fungi, the haploid nuclei from each parent
    • do not fuse right away; they coexist in the
    • mycelium, called a heterokaryon
    •  In some fungi, the haploid nuclei pair off two to a cell; such a mycelium is said to be dikaryotic  Hours, days, or even centuries may pass before the occurrence of karyogamy, nuclear fusion
    •  During karyogamy, the haploid nuclei fuse,
    • producing diploid cells
    •  The diploid phase is short-lived and undergoes
    • meiosis, producing haploid spores
    •  The paired processes of karyogamy and meiosis
    • produce genetic variation
  • Asexual Reproduction
    •  In addition to sexual reproduction, many fungi can
    • reproduce asexually
    •  Molds produce haploid spores by mitosis and
    • form visible mycelia
32

• Define plasmogamy, heterokaryotic, dikaryotic, and karyogamy.

Plasmogamy is the union of cytoplasm from two
parent mycelia
 In most fungi, the haploid nuclei from each parent
do not fuse right away; they coexist in the
mycelium, called a heterokaryon
 In some fungi, the haploid nuclei pair off two to a cell; such a mycelium is said to be dikaryotic
 Hours, days, or even centuries may pass before the occurrence of karyogamy, nuclear fusion
 During karyogamy, the haploid nuclei fuse,
producing diploid cells
 The diploid phase is short-lived and undergoes
meiosis, producing haploid spores
 The paired processes of karyogamy and meiosis
produce genetic variation

33

• Understand how budding occurs as a method of asexual reproduction.

Asexual reproduction in which a part of the parent organism pinches off and forms a new organism.

34

• Characterize (life/reproduction cycle, nutritional mode, unique structural features, and examples when provided in the text) the following groups of organisms:

...

35

o Ascomycetes (Ascomycota)

Ascomycetes
 Ascomycetes (phylum Ascomycota) live in marine, freshwater, and terrestrial habitats
 Ascomycetes produce sexual spores in saclike
asci contained in fruiting bodies called ascocarps
 Ascomycetes are commonly called sac fungi
 Ascomycetes vary in size and complexity from
unicellular yeasts to elaborate cup fungi and
morels

 Neurospora crassa, a bread mold, is a model
organism with a well-studied genome
 Ascomycetes reproduce asexually by enormous
numbers of asexual spores called conidia
 Conidia are not formed inside sporangia; they are
produced asexually at the tips of specialized
hyphae called conidiophores
Ascomycetes include plant pathogens,
decomposers, and symbionts

36

• Be familiar with the key roles that fungi play in nutrient cycling, ecological interactions, and human welfare.

  • Fungi as Decomposers
    •  Fungi are efficient decomposers of organic
    • material including cellulose and lignin
    •  They perform essential recycling of chemical
    • elements between the living and nonliving world
  • Fungi as Mutualists
    •  Fungi form mutualistic relationships with plants,
    • algae, cyanobacteria, and animals
    •  All of these relationships have profound ecological
    • effects
  • Fungus-Plant Mutualisms
    •  Mycorrhizae are enormously important in natural
    • ecosystems and agriculture
    •  Plants harbor harmless symbiotic endophytes, fungi that live inside leaves or other plant parts
    •  Endophytes make toxins that deter herbivores and
    • defend against pathogens
    •  Most endophytes are ascomycetes
    •  Many species of ants use the digestive power of
    • fungi by raising them in “farms”
  • Fungus-Animal Mutualisms
    •  Some fungi share their digestive services with
    • animals
    •  These fungi help break down plant material in the
    • guts of cows and other grazing mammals
37

• Know the types of lichens and how lichens reproduce.

  • Lichens
    •  A lichen is a symbiotic association between a photosynthetic microorganism and a fungus
    •  Millions of photosynthetic cells are held in a mass
    • of fungal hyphae
    •  The photosynthetic component is green algae or
    • cyanobacteria
    •  The fungal component is most often an
    • Ascomycete
    •  The symbioses are so complete that lichens are
    • given scientific names
    •  Algae or cyanobacteria occupy an inner layer
    • below the lichen surface
    •  The algae provide carbon compounds,
    • cyanobacteria also provide organic nitrogen, and
    • fungi provide the environment for growth
    •  The fungi of lichens can reproduce sexually and
    • asexually
    •  Asexual reproduction is by fragmentation or the
    • formation of soredia, small clusters of hyphae with
    • embedded algae
    •  Lichens are important pioneers on new rock and
    • soil surfaces
    •  Lichens were on land 420 million years ago, and
    • these early lichens may have modified rocks and
    • soil much as they do today, helping pave the way
    • for plants