Chapter 5 Flashcards
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
2
Q
Endosymbiotic Theory
A
- Lynn Margulis
- Eukaryotic cells resulted from one prokaryotic cell engulfing another prokaryotic cell
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
4
Q
Eukaryotic Organisms Studied in Microbiology
A
- Protozoa: Unicellular, A few Colonial
- Fungi + Algae: May be unicellular, colonial, or multicellular
- Helminths (parasitic worms) + Arthropods (animal vectors of disease): multicellular except reproductive stages
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
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
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
8
Q
Significant functions of the Glycocalyx
A
- adherence (attachment)
- protection from toxic chemicals
- prevents desiccation
- functions in signal reception
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
10
Q
Cell Wall
A
-rigid, provides structural support and shape
11
Q
Cell wall of Fungi
A
-have thick inner layer of polysaccharide fibers composed of chitin
12
Q
Cell wall of Algae
A
-varies in chemical composition; may be cellulose, pectin, mannans, silicon dioxide, and calcium carbonate
13
Q
Cell wall of Animals
A
no cell wall
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
15
Q
Internal Structure of Eukaryotic Cell: Nucleolus
A
-dark area for rRNA synthesis and ribosome assembly
16
Q
Internal Structure of Eukaryotic Cell: Endoplasmic Reticulum
A
Two types:
- Rough Endoplasmic Reticulum (RER)
- Smooth Endoplasmic Reticulum (SER)
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
18
Q
Smooth Endoplasmic Reticulum (SER)
A
- closed tubular network without ribosomes;
- functions in nutrient processing, synthesis, and storage of lipids
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
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
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
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
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
24
Q
Fungi: Dimorphism
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)
26
Fungi: Reproduction
- asexual
| - sexual
27
Fungal Structure: Yeast
soft, uniform texture and appearance
| -reproduce through an asexual process called budding
28
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
29
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
30
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
31
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
32
Subtypes of Asexual Mold Spores
a. Sporangiospore
| b. Conidia
33
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
35
Fungal Classification: Phylum Zygomycota
zygospores; mostly sporangiospores and some conidia
36
Fungal Classification: Phylum Ascomycota
ascospores; conidia
37
Fungal Classification: Phylum Basidiomycota
basidiospores; conidia
38
Fungal Classification: Phylum Chytridomycota
flagellated spores
39
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
41
Examples of Ascomycetes
- Penicillium
- Saccharomyces
- Histoplasma
- Microsporum
- Coccidioides
- Candida
- Stachybotrys
- Pneumocystis
42
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
43
Examples of Basidiomycetes
- mushrooms
- puff balls
- bracket fungi
- Rusts (plant fungi)
- Smuts (plant fungi)
- Cryptococcus
- Claviceps
44
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
45
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
46
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)
47
Fungi: Mycoses
fungal infections
- Systemic (whole body; inhaling)
- Subcutaneous (under skin; requires puncture)
- Cutaneous (in and on skin)
48
Mycoses: Systemic
whole body; inhaling
- Coccidioido- Coccidioidomycosis (in desert areas; carried with dust from desert)
- Histoplasma- Histoplasmosis (common in cave explorers, type of pneumonia)
49
Mycoses: Subcutaneous
under skin; requires puncture
| -Sporothrix- Sporothrixosis
50
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)
```
51
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
52
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
53
Algae Classification
- classified according to types of pigments and cell wall
| - used for cosmetics, food, and medical products
54
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
55
Algae of interest to microbiologists: Gelidium
marine red algae used to make agar
56
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
