chapter 5 power point le

8/9/2019 Chapter 5 Power Point Le

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Foundations in Microbiology

Chapter

5

PowerPoint to accompany

Fifth Edition

Talaro

Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.


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Eucaryotic cells andmicroorganisms

Chapter 5


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3 Eucaryotic cells


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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


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Flagella


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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

functions in adherence, protection, & signal reception

beneath the glycocalyxfungi 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 orcellulose & a thin layer of mixed glycans

Algae varies in chemical composition;

substances commonly found includecellulose, pectin, mannans, silicon dioxide,& calcium carbonate


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nucleus

compact sphere, most prominent organelleof eucaryotic cell

nuclear envelope is composed of twoparallel membranes separated by a narrowspace & is perforated with pores

contains chromosomes nucleolus dark area for rRNA synthesis &ribosome assembly


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nucleus


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Mitosis


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Endoplasmic reticulum

Rough endoplasmic reticulum (RER) originatesfrom the outer membrane of the nuclear envelop &extends in a continuous network throughcytoplasm; rough due to ribosomes, proteins aresynthesized & shunted into the ER for packaging& transport. First step in secretory pathway.

Smooth endoplasmic reticulum (SER) closedtubular network without ribosomes, functions innutrient 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

Transistional vesicles from the ER containingproteins 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 ofareobic respiration

divide independently of cell

contain DNA and procaryotic ribosomes function in energy production


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mitochondria


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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 chemicalenergy through photosynthesis

primary producers of organic nutrients for other

organisms


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chloroplast


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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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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


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microscopic fungi

exist in 2 morphologies

yeast round ovoid shape, asexual

reproductionhyphae long filamentous fungi or molds

some exist in either form dimorphic

characteristic of pathogens


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Morphology of yeasts


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Hyphae or mold


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Fungal nutrition

all are heterotrophic

majority are harmless saprobes living off deadplants & animals

some are parasites, living on the tissues of otherorganisms, but none are obligate; mycoses fungal infections

growth temperature 20o

-40o

C extremely widespread distribution in many

habitats


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Fungal Reproduction

primarily through spores formed on special

reproductive hyphae

asexual reproduction spores are formedthrough budding or in conidia or

sporangiospores

sexual reproduction spores are formedfollowing 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

4. Deuteromycota no sexual spores


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I. Zygospores


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II. Ascospores


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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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Kingdom Protista

algae

protozoa


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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 aquatichabitats

produce large proportion of atmospheric O2

used for cosmetics, food & medical products

Dinoflagellates cause red tides & give off

toxins


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Protozoa

65,000 species

most are unicellular, colonies are rare

most have locomoter structures flagella, cilia, orpseudopods

vary in shape

lack a cell wall & chloroplasts

can exist in trophozoite- motile feeding stage orcyst 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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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 ofhost 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 , nonsegmentedworms with sucking mouthparts

1. roundworms (nematodes)- round, a complete

digestive tract, a protective surface cuticle,spines & hooks on mouth; excretory & nervoussystems 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 carriedby insect vectors

afflict billions of humans


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