Download File - Microbiology

PowerPoint to accompany
Microbiology:
A Systems Approach
Cowan/Talaro
Chapter 5
Eucaryotic Cells and
Microorganisms
Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Chapter 5
Topics
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Eucaryotes
External structures
Internal structures
Fungi
Protists
Helminths
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Eucaryotes
• External and internal structures are
more complex than procaryotes
• Examples of eucaryotes
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Yeast
Protozoa
Algae
Helminths
Animal cells
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The structure of algae, yeast and protozoa.
Fig. 5.2 The structure of three representative eucaryotic cells
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External Structures
• Appendages
– Flagella
– Cilia
• Glycocalyx
• Cell wall
• Cell membrane
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A flagellum enables locomotion, and is composed of microtubules,
arranged in a 9 + 2 fashion.
Fig. 5.3 The structure of microtubules
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Paramecium have cilia, which are similar to flagella but are
smaller and more numerous.
Fig. 5.4 Structure and locomotion in ciliates
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Glycocalyx
• Complex outer layer
– polysaccharides and network fibers
• Protection
• Adherence
• Reception of signals from other cells
and the environment
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Cell wall
• Chitin
• Glycoprotein
• Mixed glycans
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Cell membrane
• Various sterols within the membrane will
increase rigidity and stability
• Some cells will only possess a
membrane
• Embedded transport proteins
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A representation of the glycocalyx, cell wall, and membrane.
Fig. 5.5 Boundary structure
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Internal Structures
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Nucleus
Endoplasmic reticulum
Golgi apparatus
Mitochondria
Chloroplast (photosynthetic cells only)
Ribosomes
Cytoskeleton
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Nucleus
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Membrane bound organelle
Chromatin- chromosomal DNA
Nucleolus- site for RNA synthesis
Histones-proteins that associate with
DNA during mitosis
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An electron micrograph section of the nucleus showing its
contents.
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Fig. 5.6 The nucleus
Eucaryotic cell division involves mitosis, in which the cell and
nucleus undergo several stages of change.
Fig. 5.7 changes in the cell and nucleus
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Endoplasmic reticulum (ER)
• Two types
– Rough endoplasmic reticulum (RER)
– Smooth endoplasmic reticulum (SER)
• Nuclear envelope form membrane for
the ER
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RER
• Coated with ribosomes
• Site of proteins synthesis
• Transport material from the nucleus to
the cytoplasm and cell membrane
• Transitional vesicles
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The rough endoplasmic reticulum (RER) is the site of protein
synthesis and transport into the cistern.
Fig. 5.8 The origin and detailed structure of the RER
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Golgi apparatus
• Closely associated with the ER
• Site for protein modification
• Cisternae – noncontinuous membrane
network
• Condensing vesicles
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Transitional vesicles leave the ER and enter the Golgi
apparatus,and condensing vesicles leave the Golgi apparatus.
Fig. 5.9 Detail of the
Golgi apparatus
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Organelles cooperate in protein synthesis and transport.
Fig.5.10 The
transport process
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Lysosomes are transitional vesicles that contain enzymes for
digestion of food particles.
Fig. 5.11 The origin and action of
lysosomes in phagocytosis
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Mitochondria
• Site of energy generation
• Cristae-folds of the inner membrane
• Matrix-consist of ribosomes, DNA, and
enzymes
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The structure of the mitochondria and its contents.
Fig. 5.12 General structure
of a mitochondrion
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Chloroplast
• Site of photosynthesis
• Thylakoids- folded membrane
containing the green pigment
chlorophyll
• Stroma- surrounds the thylakoids
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The thylakoid is the site for the transformation of solar energy to
chemical energy, which is then used to synthesize carbohydrates
in the stroma.
Fig. 5.13 Detail of an algal
chloroplast
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Ribosomes
• Associated with proteins synthesis
• Present in the cytoplasm and the
surface of the ER
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Cytoskeleton
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Anchor organelles
Cellular structural support
Enable cell shape changes
Two types
– Microfilaments
– Microtubules
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Microfilaments allow movement of molecules in the cytoplasm,
and microtubules maintain shape of the cell and enable
movement of molecules within the cell.
Fig. 5.14 A model of the cytoskeleton
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Fungi
• Present in nature (ex. mushrooms)
• Medically important (ex. athlete’s foot)
• Industrially important (ex. fermentation)
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Fungi
• Classification
– Morphology
– Reproduction (asexual and sexual)
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Morphology and Reproduction
• Hyphae cell
– Septate
– nonseptate
• Yeast cells
– Single cells
– Pseudohypha
• Reproduction
– Asexual and sexual process
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A scanning electron micrograph of the hyphae cells.
Fig. 5.15 Diplodia maydis, a pathogenic fungus
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A scanning electron micrograph of yeast cells, and the budding
reproductive process .
Fig. 5.16 Microscopic morphology of yeasts
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An example of the mold Rhizopus, and its stages of hyphae
reproduction.
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Fig. 5.18 Functional types of hyphae using the mold as an example.
Asexual spore formation involves the mitotic division of a single
parental cell.
Fig. 5.19 Types of asexual mold spores
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Sexual spore formation involves the fusion of two parental nuclei
followed by meiosis.
Fig. 5.20 Formation of zygospores
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Mushrooms undergo sexual spore formation.
Fig. 5.22 Formation of basidiospores in a mushroom
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Subkingdoms of Fungi
• Amastigomycota
– Perfect
– Imperfect
• Mastigomycota
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Black bread mold is classified as a Amastigomycota (Perfect).
Fig. 5.23 A representative Zygomycota
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Penicillium is another example Amastigomycota (Perfect).
Fig. 5.24 A common Ascomycota
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Mycelium is classified as an Amastigomycota (Imperfect).
Fig. 5.25 Mycelium and spores of a representative
of Deuteromycota
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Fungi are capable of causing superficial and systemic infections.
Table 5.2 Major
fungal infections
of humans
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Protista
• Algae
• Protozoa
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Algae
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Photosynthetic
Inhabitants of fresh and marine waters
Most are not considered human pathogens
Pathogens produce toxins (ex. red tide)
Unique morphology enables identification
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Algae contain green chlorophyll as well as other pigments which
include yellow, red and brown.
Fig. 5.26 Representative microscopic algae
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Protozoa
• Complex structure and function
– Ectoplasm and endoplasm
– Pseudopods, flagella, cilia
• Inhabitants of fresh water and soil
– Heterotrophs
• Reproduction (asexual)
– Trophozoite
– Encystment
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An example of the complex structure associated with the protozoa
Trichomonas vaginalis.
Fig. 5. 28 The structure of a typical mastigophoran
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Typical life cycle associated with most protozoa.
Fig. 5.27 The general life cycle exhibited by many protozoa.
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Medically important protozoa
• Amoeboid protozoa
– Brain infections
• Flagellated protozoa
– Giardiasis
• Apicomplexan protozoa
– Malaria
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Representation of pathogenic amoebas, and nonpathogenic
shelled amoebas.
Fig. 5.29 Examples of sarcodinians
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Representation of a ciliated protozoa, which are generally freeliving and harmless.
Fig. 5.30 Selected ciliate representatives
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Representation of an apicomplexa, which are considered an
intracellular parasite.
Fig. 5.31 Sporozoan protozoan
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The cycle of transmission involves the protozoa, host and vectors.
Fig. 5.32 Cycle of transmission
in Chagas disease
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The stages of development and transmission of amoebic
dysentery in the human host.
Fig. 5.33 Stages in the
infection and transmission of
Amoebic dysentery
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Helminths
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Tapeworms
Flukes
Roundworms
Unique structural morphology enables
identification
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Helminths are multicellular animals with organ-like systems.
Fig. 5.34 Parasitic flatworms
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The pinworm life cycle in the human host.
Fig. 5.35 The life cycle
of the pinworm, a
roundworm
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Humans serve as a host for the life cycle of many different
parasitic helminths.
Table 5.4 Major helminths of humans and their
modes of transmission.
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