Microbiology > Chapter 5 > Flashcards

Chapter 5 Flashcards

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1
Q

History of Eukaryotic Cells

A

-Originated 2 billion years ago
-Endosymbiotic Theory (Lynn Margulis)
>Eukaryotic cells resulted from one prokaryotic cell engulfing another prokaryotic cell
-Evidence:
>some eukaryotic organelles resemble prokaryotic cells:
-Mitochondria + Chloroplasts are rod-shaped, measured in ums, have 70S ribosomes, have own DNA that is similar to prokaryotic DNA

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2
Q

Endosymbiotic Theory

A
  • Lynn Margulis

- Eukaryotic cells resulted from one prokaryotic cell engulfing another prokaryotic cell

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3
Q

Endosymbiotic Theory: Evidence

A

Some Eukaryotic organelles resemble prokaryotic cells
-Mitochondria + Chloroplasts are rod-shaped, measured in ums, have 70S ribosomes, have own DNA that is similar to prokaryotic DNA

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4
Q

Eukaryotic Organisms Studied in Microbiology

A
  1. Protozoa: Unicellular, A few Colonial
  2. Fungi + Algae: May be unicellular, colonial, or multicellular
  3. Helminths (parasitic worms) + Arthropods (animal vectors of disease): multicellular except reproductive stages
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5
Q

External Structure of Eukaryotic Cell: Locomotor appendages: Flagellum(a)

A
  • long, sheathed cylinder containing microtubules in a 9+2 arrangement
  • composed of protein tubulin
  • 10x thicker than prokaryotic flagella
  • function in motility
  • Mechanism of Action: wavelike
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6
Q

External Structures of Eukaryotic Cell: Locomotor appendages: Cilia

A
  • similar in overall structure to flagella, but shorter and more numerous
  • found only on a single group of protozoa and certain animal cells-function in motility, feeding, and filtering
    ex: paramecium
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7
Q

External Structures of Eukaryotic Cell: Glycocalyx

A
  • an outermost boundary that comes into direct contact with environment
  • usually composed of polysaccharides
  • appears as a network of fibers, either a slime layer or a capsule
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8
Q

Significant functions of the Glycocalyx

A
  • adherence (attachment)
  • protection from toxic chemicals
  • prevents desiccation
  • functions in signal reception
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9
Q

Beneath the Glycocalyx

A
  • Fungi and most algae have a thick, rigid cell wall

- Protozoa, a few algae, and all animal cells lack a cell wall and have only a membrane

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10
Q

Cell Wall

A

-rigid, provides structural support and shape

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11
Q

Cell wall of Fungi

A

-have thick inner layer of polysaccharide fibers composed of chitin

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12
Q

Cell wall of Algae

A

-varies in chemical composition; may be cellulose, pectin, mannans, silicon dioxide, and calcium carbonate

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13
Q

Cell wall of Animals

A

no cell wall

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14
Q

Internal Structure of Eukaryotic Cell: Nucleus

A
  • control center of the eukaryotic cell
  • envelope composed of two parallel membranes separated by a narrow space; perforated with pores
  • contains species specific number of chromosomes
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15
Q

Internal Structure of Eukaryotic Cell: Nucleolus

A

-dark area for rRNA synthesis and ribosome assembly

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16
Q

Internal Structure of Eukaryotic Cell: Endoplasmic Reticulum

A

Two types:

  1. Rough Endoplasmic Reticulum (RER)
  2. Smooth Endoplasmic Reticulum (SER)
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17
Q

Rough Endoplasmic Reticulum (RER)

A
  • originates from the outer membrane of the nuclear envelope
  • extends in a continuous network through cytoplasm;
  • proteins synthesized on ribosomes;
  • shunted into the ER for packaging and transport; first step in secretory pathway
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18
Q

Smooth Endoplasmic Reticulum (SER)

A
  • closed tubular network without ribosomes;

- functions in nutrient processing, synthesis, and storage of lipids

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19
Q

Internal Structure of Eukaryotic Cell: Golgi Apparatus

A
  • modifies, stores, and packages proteins
  • secretes vesicles
  • consists of a stack of flattened sacs called cisternae
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20
Q

Internal Structure of Eukaryotic Cell: Mitochondria

A
  • function in energy production
  • outer membrane and an inner membrane with folds called cristae
  • cristae hold the enzymes and electron carriers of aerobic respiration
  • divide independently of cell
  • contain DNA and 70S prokaryotic ribosomes
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21
Q

Internal Structure of Eukaryotic Cell: Chloroplast

A
  • convert the energy of sunlight into chemical energy through photosynthesis
  • found in algae and plant cells
  • outer membrane covers inner membrane folded into sacs, thylakoids, stacked into grana
  • primary producers of organic nutrients for other organisms
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22
Q

Internal Structure of Eukaryotic Cell: Ribosomes

A
  • 80S
  • composed of rRNA and proteins
  • scattered in cytoplasm or associated with RER
  • function in protein synthesis
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23
Q

Fungi

A
  • Eukaryotic Cell
  • Single or Multicellular
  • Heterotrophic
  • Mycology
  • Mycotoxins (produced by pathogenic fungi)
  • Facultative parasites
  • Saprophytes (saprobes); required dead or dying host
  • Nutrition: send out exoenzymes to break down material; absorb digested material
  • Decomposers or recyclers
  • Cell wall: Chitin
  • Membrane: Ergosterol
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24
Q

Fungi: Dimorphism

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A

ability to alter structure when changing environments

25
Fungi: Structure
- Mycelium- mass of hyphae (body) - Hyphae- fungal filaments - Septate- separated by walls - Coenocytic- no walls - may be multinucleated - Vegetative or Reproductive (aerial)
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Fungi: Reproduction
- asexual | - sexual
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Fungal Structure: Yeast
soft, uniform texture and appearance | -reproduce through an asexual process called budding
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Fungal Structure: Filamentous Fungi
mass of hyphae called mycelium; cottony, hairy, or velvety texture - Hyphae may be divided by cross walls- Septate - Hyphae may be without walls- Coenocytic - Vegetative Hyphae- digest and absorb nutrients - Reproductive hyphae- produce spores for reproduction
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Fungal Reproduction
-Sexual reproduction- spores are formed following fusion of two different strains and formation of a sexual structure (zygospore, ascospore, and basidiospores) -Sexual spores- and spore-forming structures are used for identification and are the usual basis for classification - Asexual reproduction- spores are formed through budding or mitosis; two subtypes of asexual spores: conidia and sporangiospores - Asexual spores are used for identification
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Fungal Reproduction: Sexual Reproduction
spores are formed following fusion of two different strains and formation of a sexual structure - Zygospores, ascospores, and basidiospores - sexual spores and spore-forming structures are used for identification and are the usual basis for classification
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Fungal Reproduction: Asexual Reproduction
spores are formed through budding or mitosis; two subtypes of asexual spores: conidia and sporangiospores -asexual spores are used for identification
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Subtypes of Asexual Mold Spores
a. Sporangiospore | b. Conidia
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Fungal Classification
Kingdom Eumycota is subdivided into several phyla based upon the type of sexual reproduction: - Phylum Zygomycota- zygospores; mostly sporangiospores and some conidia - Phylum Ascomycota- ascospores; conidia - Phylum Basidiomycota- basidiospores; conidia - Phylum Chytridomycota- flagellated spores
34
Fungi that produce only Asexual Spores
Imperfect or Deuteromycota - phylum of unknown origin - don't have sexual spore yet
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Fungal Classification: Phylum Zygomycota
zygospores; mostly sporangiospores and some conidia
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Fungal Classification: Phylum Ascomycota
ascospores; conidia
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Fungal Classification: Phylum Basidiomycota
basidiospores; conidia
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Fungal Classification: Phylum Chytridomycota
flagellated spores
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Formation of Zygospores
-Phylum Zygomycota -Sexual spore: zygospore -Asexual spore: Sporangiospores -Zygospore germinates, forms mycelium, that gives rise to sporangium. Meiosis of diploid cells of sporangium result in haploid nuclei that develop into sporangiospores
40
Production of Ascospores
-Phylum Ascomycota -Sexual spore: ascospore -Asexual spore: conidia -opposite mating strands (+and-) zygote nuclei that undergoes meiosis prior to formation of asci -ascospores are produced, bunch of chemicals, spores explode out the top and go all over the place
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Examples of Ascomycetes
- Penicillium - Saccharomyces - Histoplasma - Microsporum - Coccidioides - Candida - Stachybotrys - Pneumocystis
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Formation of Basidiospores in a mushroom
Phylum- basidiomycota Sexual spore: basidiospore Asexual spore: conidia -pair of nuclei fuse to form diploid nucleus, diploid nucleus undergoes meiosis to produce four haploid nuclei
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Examples of Basidiomycetes
- mushrooms - puff balls - bracket fungi - Rusts (plant fungi) - Smuts (plant fungi) - Cryptococcus - Claviceps
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Fungal Identification
-Isolation on specific media (like acidic media) - Macroscopic and Microscopic observation of: - Asexual spore-forming structures and spores - Hyphal type - Colony texture and pigmentation - Physiological characteristics - Genetic Makeup
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Adverse Effects of Fungi
- Mycoses- fungal infections - Allergies- fungal cell wall substances trigger reactions - Toxin production- aflatoxin, ergot toxin; neurological effects - Destruction of crops and food storages
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Beneficial Impact of Fungi
- Decomposers of dead plants and animals - Form associations with plant roots (mycorrhizae; helps plant get nutrients) - Aid in digestion in guts of herbivores - Sources of antibiotics, alcohol, organic acids, vitamins - Used in making foods (beer, wine, bread, soy sauce, blue cheese, cured meats) - Used in genetic studies (Recombivax; vaccination (hep B)
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Fungi: Mycoses
fungal infections - Systemic (whole body; inhaling) - Subcutaneous (under skin; requires puncture) - Cutaneous (in and on skin)
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Mycoses: Systemic
whole body; inhaling - Coccidioido- Coccidioidomycosis (in desert areas; carried with dust from desert) - Histoplasma- Histoplasmosis (common in cave explorers, type of pneumonia)
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Mycoses: Subcutaneous
under skin; requires puncture | -Sporothrix- Sporothrixosis
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Mycoses: Cutaneous
``` in and on skin -Epidermophyton spp -Microphyton spp -Tricophyton spp Tinea capitum (scalp), barberis (beard), corporis (body), unguium (nail), cruris (Tinea... latin for worm) ```
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Protists
-Eukaryotic Cells -most unicellular (sometimes colonial) some multicellular -most microscopic (5um to 5mm); some macroscopic -mostly aquatic, some marine, some moist soil, some pathogens of humans -survival mechanism: CYST -simplest method of grouping: Plant like Protists: Algae Fungus like Protists: Slime Molds Animal like Protists: Protozoa
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Algae
-photosynthetic organisms -microscopic forms are unicellular, colonial, filamentous -macroscopic forms are colonial and multicellular -contain chloroplasts with chlorophyll a and other pigments -cell wall (composition varies) -may or may not have flagella -most are free-living in fresh and marine water- PLANKTON -provide basis of food web in most aquatic habitats -produce large proportion of atmospheric O2 -most are non pathogenic Dinoflagellate can cause red tides and give off toxins that cause food poisoning
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Algae Classification
- classified according to types of pigments and cell wall | - used for cosmetics, food, and medical products
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Algae of Interest to microbiologists
1. Gelidium- marine red algae used to make agar 2. Alexandrium (aka Gonyaulax) -dinoflagellates -produces saxitoxin (neurotoxin) -causes PSP paralytic shellfish (muscles, clams, oysters) poisoning 3. Gambierdiscus (in Caribbean) -dinoflagellates -produces cigua toxin in game fish like grouper and red snapper -causes disease ciguatera -toxin not inactivated by cooking 4. Pfiesteria -dinoflagellate -2 toxins: 1 waterborne, 1 airborne Toxin attacks immune system, higher level brain function (brain damage) -Life cycle: -during winter; algae eater (amoeboid shape); kleptochloroplasts -increased run off leads to increased fish population, in response to scent of fish feces organism changes shape, becomes "clawed", tears fish to shreds
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Algae of interest to microbiologists: Gelidium
marine red algae used to make agar
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Algae of interest to microbiologists: Alexandrium (aka Gonyaulax)
- dinoflagellates - produces saxitoxin (neurotoxin) - causes PSP paralytic shellfish (muscles, clams, oysters) poisoning
57
Algae of interest to microbiologists: Gambierdiscus (in Caribbean)
- dinoflagellate - produces cigua toxin in game fish like grouper and red snapper - causes disease ciguatera - toxin not inactivated by cooking
58
Algae of interest to microbiologists: Pfiesteria
-dinoflagellate -2 toxins: 1 Waterborne, 1 Airborne Toxin attacks immune system, higher level brain function (brain damage) -Life cycle: -during winter; algae eater (amoeboid shape); kleptochloroplasts -increased run off leads to increased fish population, in response to scent of fish feces organism changes shape, becomes "clawed", tears fish to shreds
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