Transcript Foundations in Microbiology

PowerPoint to accompany
Foundations
in
Microbiology
Fifth Edition
Talaro
Chapter
5
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Eucaryotic cells and
microorganisms
Chapter 5
2
Fig. 5.p125a
Fig. 5.p125b
3 Eucaryotic cells
5
Flagella
• long, sheathed cylinder containing microtubules in
a 9+2 arrangement
• covered by an extension of the cell membrane
• 10X thicker than procaryotic flagella
• function in motility
• Common in protozoa, algae, a few fungal and
animal cells
• Placement and the number of flagella can be used
to identify flagellated protozoa and certain algae
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Flagella
Locomotion Patterns
7
Cilia
• 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 & filtering
8
Glycocalyx
• an outermost boundary that comes into direct contact
with environment
• usually composed of polysaccharides
• appears as a network of fibers, a slime layer or a
capsule (like prokaryotes)
• functions in adherence, protection, & signal reception
• beneath the glycocalyx
– fungi and most algae have a thick, rigid cell wall
– protozoa, a few algae, and all animal cells lack a
cell wall & have only a membrane
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Glycocalyx structure
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Cell wall
• rigid & provide structural support & shape
• fungi have thick inner layer of polysaccharide
fibers composed of chitin or cellulose & a thin
outer layer of mixed glycans
• Algae – varies in chemical composition;
substances commonly found include cellulose,
pectin, mannans, silicon dioxide, & calcium
carbonate
11
Cell membrane
• typical bilayer of phospholipids and
proteins
• sterols confer stability
• serve as selectively permeable barriers in
transport (functionally similar to prok.)
• eucaryotic cells also contain membranebound organelles that account for 60-80%
of their volume
12
Nucleus
• compact sphere, most prominent organelle of
eucaryotic cell
• nuclear envelope is composed of two parallel
membranes separated by a narrow space & is
perforated with pores
• contains chromosomes
• nucleolus – dark area for rRNA synthesis &
ribosome assembly
– (Ribosomes coordinate the codon of mRNA with a tRNA
anticodon and therefore is considered the peptide assembly site)
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nucleus
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Mitosis
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Endoplasmic reticulum
• Rough endoplasmic reticulum (RER)– originates
from the outer membrane of the nuclear envelop &
extends in a continuous network through
cytoplasm; rough due to ribosomes, proteins are
synthesized & shunted into the ER for packaging
& transport. First step in secretory pathway.
• Smooth endoplasmic reticulum (SER)– closed
tubular network without ribosomes, functions in
nutrient processing, synthesis & storage of lipids,
etc.
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rough endoplasmic reticulum
(RER)
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Golgi apparatus
• consists of a stack of flattened sacs called
cisternae
• closely associated with ER
• Transitional vesicles from the ER containing
proteins go to the Golgi apparatus for modification
and maturation
• Condensing vesicles transport proteins to
organelles or secretory proteins to the outside
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Golgi apparatus
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Transport process
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lysosomes
• vesicles containing enzymes
• involved in intracellular digestion of food
particles & in protection against invading
microbes
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lysosomes
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mitochondria
• consists of an outer membrane & an inner
membrane with folds called cristae
• cristae hold the enzymes & electron carriers
of areobic respiration
• divide independently of cell
• contain DNA and procaryotic ribosomes
• function in energy production- ATP
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Mitochondria
Matirix-holds ribosomes, DNA,
and enzymes, compounds for
metabolic cycle
Cristae-holds the enzymes and
electron carriers of aerobic
respiration
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chloroplast
• found in algae & plant cells
• outer membrane covers inner membrane folded
into sacs, thylakoids, stacked into grana
• larger than mitochondria
• contain photosynthetic pigments
• convert the energy of sunlight into chemical
energy through photosynthesis
• primary producers of organic nutrients for other
organisms
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Chloroplast
Thylakoids- disclike sacs stacked into Granum
Stoma-matrix
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cytoskeleton
• flexible framework of proteins,
microfilaments & microtubules form
network throughout cytoplasm
• involved in movement of cytoplasm,
ameboid movement, transport, & structural
support
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cytoskeleton
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ribosomes
•
•
•
•
composed of rRNA and proteins
40S and 60S subunits form 80S ribosomes
larger than procaryotic ribosomes
function in protein synthesis
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Fig. 5.p124
Survey of eucaryotic microbes
•
•
•
•
Fungi
Algae
Protozoa
Parasitic helminths
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Kingdom Fungi
• 100,000 species divided into 2 groups:
– macroscopic fungi ( mushrooms, puffballs, gill fungi)
– microscopic fungi (molds, yeasts)
• majority are unicellular or colonial, a few have
cellular specialization
• Survived on earth for 650 million years
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microscopic fungi
• exist in 2 morphologies
– yeast – round ovoid shape, asexual
reproduction
– hyphae – long filamentous fungi or molds
• some exist in either form – dimorphic –
characteristic of pathogens
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Hyphae or mold
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Morphology of yeasts
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Fungal nutrition
• all are heterotrophic
• majority are harmless saprobes living off dead
plants & animals
• some are parasites, living on the tissues of other
organisms, but none are obligate; mycoses –
fungal infections
• growth temperature 20o-40oC
• extremely widespread distribution in many
habitats
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Fig. 5.17
Fungal Reproduction
• primarily through spores formed on special
reproductive hyphae
– asexual reproduction – spores are formed
through budding or in conidia or
sporangiospores
– sexual reproduction – spores are formed
following fusion of male & female strains &
formation of sexual structure
• sexual spores are one basis for classification
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Asexual mold spores
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4 main divisions based on spore type
1. Zygomycota
2. Ascomycota
3. Basidiomycota
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I. Zygospores
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A Representative Zygomycota
II. Ascospores
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A Common Ascomycota,
Penicillium
Macroscopic blue-green colonies
Microscopic view of
phialospores, the asexual phase
III. Basidospores
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Roles of fungi
•
•
•
•
decomposers of dead plants and animals
sources of antibiotics
used in making foods & in genetic studies
adverse impact – food spoilage, mycoses,
toxin production
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Table 5.1
Kingdom Protista
• algae
• protozoa
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Algae
• photosynthetic organisms
• kelps, seaweeds, euglenids, green algae, diatoms,
dinoflagellates, brown algae, & red seaweeds
• contain chloroplasts with chlorophyll & other
pigments; cell wall; may or may not have flagella
• microscopic forms are unicellular, colonial,
filamentous
• macroscopic forms are colonial and multicellular
• most are free-living in fresh and marine water
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Algae
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Algae
• classified according to types of pigments &
cell wall
• provide basis of food web in most aquatic
habitats
• produce large proportion of atmospheric O2
• used for cosmetics, food & medical products
• Dinoflagellates cause red tides & give off
toxins
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Table 5.2
Protozoa
• 65,000 species
• most are unicellular, colonies are rare
• most have locomoter structures – flagella,
cilia, or pseudopods
• vary in shape
• lack a cell wall & chloroplasts
• can exist in trophozoite- motile feeding
stage or cyst – a dormant resistant stage
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Protozoa
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Protozoa
• all are heterotrophic,
• most are free-living in a moist habitat
• feed by engulfing other microbes & organic
matter
• some are animal parasites & can be spread
by insect vectors
• asexual and sexual reproduction
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Groups based on locomotion &
reproduction
•
•
•
•
Mastigophora – flagellates
Sarcodina – amebas
Ciliophora – ciliates
Apicomplexa – all parasites motility not
well developed; produce unique
reproductive structures
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Mastigophora – flagellates
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Sarcodina – amebas
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Ciliophora – ciliates
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Ciliate Representatives
Fig. 5.31
Apicomplexa
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Parasitic Helminths
• multicellular animals, organs for reproduction,
digestion, movement, protection
• parasitize host tissues
• have mouthparts for attachment to or digestion of
host tissues
• most have well-developed sex organs that produce
eggs and sperm.
• fertilized eggs go through larval period in or out of
host body
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Major groups of helminths
1. flatworms – flat, no definite body cavity;
digestive tract a blind pouch; simple excretory &
nervous systems
•
•
cestodes (tapeworms)
trematodes or flukes, are flattened , nonsegmented
worms with sucking mouthparts
2. roundworms (nematodes)- round, a complete
digestive tract, a protective surface cuticle,
spines & hooks on mouth; excretory & nervous
systems poorly developed
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Helminths
• 50 species parasitize humans
• acquired though ingestion of larvae or eggs
in food; from soil or water; some are carried
by insect vectors
• afflict billions of humans
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