1. EUKARYOTIC CELL
BIOLOGY AND
MICROORGANISM
Advance Microbiology

2. Eukaryotic Cell Structure
In contrast to prokaryotes, eukaryotes contain a
membrane-enclosed nucleus and several other organells.

3. Nucleus • The nucleus is enclosed by pair of membranes, the inner
• The nucleus contains the genome of the
eukaryotic cell.
• In eukaryotic, DNA within the nucleus is
wound around histones to form
nucleosomes, and from them
chromosomes.
• The nucleus is enclosed by pair
of membranes, the inner
membrane is a simple sac, while
the outer membrane is in many
places continuous with the
endoplasmic reticulum.

4. • The inner and outer nuclear membranes specialize in
interactions with the nucleoplasm and the cytoplasm,
respectively.
• The nuclear membrane also contains pores, formed from
holes where the inner and outer membranes are joined. The
pores allow a complex of proteins to import and export other
proteins and nucleic acids into and out of the nucleus, a
process called nuclear transport.
• Within the nucleus, the nucleolus is the site of ribosomal RNA
synthesis.
Eukaryotic Cell Structure And Function

5. The nucleus. Electron
micrograph of a yeast
cell by freez-etching,
showing a surface view
of the nucleus.

6. Respiratory and Fermentative Organells:
the Mithocondrion and the Hydrogenosome
Mitochondria
• For respiration and oxidative phosphorylation (a mechanism
of ATP formation).
• Can be rod-shaped or nearly spherical.
• A typical animal cell can contain over 1000 mitochondria.
• Surronded by two membranes. The outer membrane,
composed of an equal mixture of protein and lipid, relatively
permeable and contains numerous minute channels that
allow passage of ions and small organic molecules. The inner
membrane is more protein rich and is also less permeable.
Eukaryotic Cell Structure And Function

7. • Mitochondria also possess a series of folded internal
membranes called cristae, the sites o enzymes involved in
respiration and ATP production.
• The matrix contains a number of enzymes involved in the
oxidation of organic compounds-in particular, enzymes of the
citric acid cycle.
Diagram showing the overall structure of the mitochondrion. Note inner and
outermost membranes.
Eukaryotic Cell Structure And Function

8. tissue, showing the variability in morphology. Note the cristae.
Tranmission electron micrographs of mitochondria from rat
tissue, showing the variability in morphology. Note the cristae.
Eukaryotic Cell Structure And Function

9. • Some anaerobic eukaryotic microorganisms lack mitochondria
The Hydrogenosome
• Some anaerobic eukaryotic microorganisms lack mitochondria
and contain instead a hydrogenosome.
• The hydrogenosome lacks cristae and citric acid cycle.
Electron micrograph of a thin section through a cell of the
anaerobic flagellate, Trichomonas vaginalis.
Eukaryotic Cell Structure And Function

10. Biochemistry of the hydrogenosome

11. Photosynthetic Organells: The Chloroplast
• Chloroplasts are choropyll-
containing organelles found in
phototrophic eukaryotes-
algae.
• Chloroplasts have permeble
outermost membrane, a much
less permeable inner
membrane, and an
intermembrane space.
• The inner membrane
surrounds the lumen of the
chloroplast, called the Stroma. a b
Photomicrographs of algal cells
showing chloroplasts. (a)
Stephanodiscus, (b) Spirogyra,
spiral-shaped chloroplasts

12. • Instead, chlorophyll and all other components needed for
photosynthesis are located in a series of flattened membrane
discs called thylakoids. In green algae and green plants,
thylakoids are typically stacked into discrete structural units
called grana.
• The chloroplats stroma contains large amounts of the enzyme
ribulose bisphosphate carboxylase (RubisCo), a key catalist of
the calvin cycle, the series of biosynthetic reactions by which
most photosynthetic organism convert CO2 into organic
compound.
Chloroplast
Thylakoid
Chloroplast of the golden
brown alga Ochromonas
danica. Note thylakoids.

13. Endosymbiosis: Relationships of Mithocondria and
Chloroplasts to Bacteria 1. 2. 3. 4. 5.
Mithochondria and chloroplasts contain DNA
The eukaryotic nucleus contains bacterially derived genes
Mitochondria and chloroplasts contain their own ribosomes
70S-same as prokaryotes ribosomes.
Antibiotic specifity
Several antibiotics (ex. Streptomycin) kill or inhibit bacteria. These same
antbiotics also inhibit protein synthase in mitocondria and chloroplast.
Molecular phylogeny
Using comparative ribosomal RNA sequencing methods and oranellar
genome studies have shown convincingly that the chlorolpast and
mitochondrion originated from the Bacteria.
Eukaryotic Cell Structure And Function

14. Other Organelles and Eukaryotic Cell Structure
Endoplasmic Reticulum (ER)
• Is a network of membranes continuous with the nuclear
membrane.
• Two types: rough, which contains attached ribosomes, and
smooth, which does not.
• Smooth ER participates in the synthesis of lipids and in some
aspects of carbohydrate metabolism.
• Rough ER, through the activity of its ribosomes, is a major
producer of glycoproteins and also produces new membrane
material.
Eukaryotic Cell Structure And Function

15. • Consists of a stack of membranes distinct from the ER, but
Golgi Complex
• Consists of a stack of membranes distinct from the ER, but
which functions in concert with the ER.
• In the golgi complex products of the ER are chemically
modified and sorted into those destinied to secreted, for
example hormones or digestive enzymes.
Cell of the protozoan Toxoplasma gondii. The golgi is colored in red.
Eukaryotic Cell Structure And Function

16. Are membrane-enclosed structures that contain various
Lysosomes
Are membrane-enclosed structures that contain various
digestive enzymes that the cell uses to digest macromolecules
such as proteins, fats, and polysacharides.
Peroxisome
is a membrane-enclosed structures whose function is to
produce hydrogen peroxide (H2O2) from the reduction of O2
by various hydrogen donors, including alcohols and long chain
fatty acids. The H2O2 produced in the peroxisome is degraded
to H2O and O2 by enzyme catalase.
Eukaryotic Cell Structure And Function

17. Microfilaments and Mirotubules
• These structures form the cell cytoskeleton.
• Microfilaments are about 8 nm in diameter and are polymers
of the protein actin. These fibers form scaffolds throughout
the cell, defining, and maintaining the shape of the cell.
• Mirotubules are larger filaments, about 25 nm in diameter,
and are composed of the protein tubulin. Microtubules assist
microfilaments in maintaining cell structure.
• They also play an important role in cell motility.
Eukaryotic Cell Structure And Function

18. Microfilaments and eukaryotic cell architecture
Eukaryotic Cell Structure And Function

19. • Are organelles of motility, allowing cells to move by swimming
Flagella and Cilia
• Are organelles of motility, allowing cells to move by swimming
motility.
• Cilia are essentially short flagella that beat in synchrony to
propel the cell – usually quite rapidly – through the medium.
• Flagella are long appendages present singly or in groups that
push the cell along – typically more slowly than by cilia –
through a whip-like motion.
Eukaryotic Cell Structure And Function

20. Overview of Eukaryotic Genetic
• Eukaryotic cells divided by mitosis and then undergo sexual
reproduction.
• From a genetic standpoint, eukaryotic cells can exist in two
forms: haploid or diploid.
• Mitosis is the process following DNA replication in a cell in
which chromosomes condense, divide, and are separated into
two sets, one for each doughter cell.
• Meiosis is the process by which the conversion from the
diploid to the haploid stage occurs.
Eukaryotic Genetics

21. Mitosis, as seen in the light microscope
Metaphase,
chromosome are
paired in the center
of the cell.
Anaphase,
Chromosome are
separating
Eukaryotic Genetics

22. The Mating Process in Yeast: Mating Types
Life cycle of a typical yeast, Sacharomyces cerevisiae. A haploid cell
of S. Cerevisiae contain 16 chromosome.
Eukaryotic Genetics

23. Eukaryotic Microbial Diversity
Phylogenetic tree based on comparative 18S ribosomal RNA
sequences. Note how endosymbionts (mitochondria and chloroplasts)
are shown to originate in the domain Bacteria.

24. A phylogenetic tree based on other eukaryotic genes and proteins
Eukaryotic Microbial Diversity

25. Characteristics of the major groups of protozoa
Typical
representatives
Trypanosoma,
Giardia,
Leishmania,
Trichomonas
Euglena
Amoeba,
Entamoeba
Balantidium,
Paramaecium
Group
Mastigophora
Euglenoids
Sarcodina
Ciliophora
Common Name
Flagellates
Photorophic
flagellates
Amebas
Ciliates
Habitats
Freshwater;
parasites of
animals
freshmarine
Freshwater and
marine; animal
parasites
parasites; rumen
Common deases
African sleeping
sickness,
giardiasis,
leishmaniasis
None known
Amebic dysentery
(amebiasis)
Dysentery
Primarily animal
Plasmodium,
Toxoplasma
parasites; insects
(vector for parasitic
Malaria,
toxoplasmosis
Apiconplexa
Sporozoans
deseases)

26. Typical protozoa. (a) Amoeba. (b) A typical ciliate, Paramaecium. (c) A
flagellate, Dunaliella (this flagellate contains chlooroplasts and thus can
also be consider an alga). (d) Plasmpdium vivax, an apicomplexan
sporozoan, growing in a human red blood cell.
Eukaryotic Microbial Diversity

27. Photomicrograph of the flagellated protozoan Trypanosoma brucei, the
Membrane flap
Red blood cell
Trypanosomes.
Photomicrograph of the
flagellated protozoan
Trypanosoma brucei, the
causative agent of African
sleeping sickness, from a blood
smear.
Trypanosoma cell
Shelled amoebae:
foraminifera. Note the
ornate and multilobed test.
Eukaryotic Genetics

28. Side view of a moving amoeba, Amoeba proteus, taken from a film. The
time interval from top to bottom is about 6 second. The arrows point to a
fixed spot on the surface. A single cell is about 80 μm in diameter.

29. Paramaecium, a ciliated protozoan
Yeast cell (for scale)
Mouth (gullet)
Eukaryotic Microbial Diversity

30. Slime Molds • Slime molds are microbial eukaryotes that have
phenotipic similarity to both fungi and protozoa. Like
fungi, slime molds undergo a life cycle and can
produce spores. However, like protozoa slime molds
are motile and can move across a solid surface rather
rapidly.
• Divided into two groups, cellular slime molds, whose
vegetative forms are composed of single amoebae,
and the acellular slime molds, whose vegetative
forms are masses of protoplasm of indefinitife size
and shape called plasmodia.

31. Slime molds. Plasmodia of the acellular slime mold Physarum
growing on an agar surface
Eukaryotic Microbial Diversity

32. Eukaryotic Microbial Diversity
Photomicrograph of various stages in the life cycle of the celullar slime
mold Dictyostellium discoideum.(a) Amoebae in preaggregation stage. (b)
Aggregating amoebae. (c) Low-power view of aggregating amoebae. (d)
Migrating pseudoplasmodia (slugs) moving on an agar surface and leaving trails
of slime in their wake. (e,f) Early stage of fruiting body, (g) Mature fruiting body.
Eukaryotic Microbial Diversity

33. Eukaryotic Microbial Diversity
Stages in fruiting-body formation in the cellular slime mold
Dictyostellium discoideum. (A-C) Aggregation of amoebae;
aggregtaion is triggered by cAMP. (D-G) Migration of the slug formed
from aggregated ampebae. (H-L) Culmination and formation of the
fruit-ing body. (M) Mature fruiting body composed of stalk and head.
Eukaryotic Microbial Diversity

34. Fungi Fungi include the molds and yeast. Fungi differ
from protozoa by virtue of their rigid cell wall,
production of spores, lack of motility, and
phylogenetic position. Mushrooms are large,
often edible fungi that produce fruiting bodies
containing basidiospores.
Eukaryotic Microbial Diversity

35. Filamentous Fungi: Molds
• They are widespread in nature and are commonly seen on
stale bread, cheese, or fruit.
• Each filament grows mainly at the tip, by extension of the
terminal cell.
• A single filament is called hypha, a collectively called a
mycelium.
• Has aerial branches spores called conidia. Conidia are asexual
spores.
• Some molds also produce sexual spores (different type
depending on the group). Sexual spores of fungi are typically
resistant to drying, heating, freezing, and some chemical
agents.
Eukaryotic Microbial Diversity

36. Mold Structure and Growth
Diagram of a mold life cycle. Conidia can
be either wind-blown or be trasported by
animals.
Photomicrograph of a typical mold.
Conidia are seen as the spherical
structure and the ends of aerial hyphae.
Eukaryotic Microbial Diversity

37. (a) Conidiophore and conidia of Aspergillus fumigatus. (b) Colonies
of an Aspergillus species growing
on an agar plate.
Eukaryotic Microbial Diversity a

38. Characteristics and major properties of fungi
Typical
representati
ves
Neurospora,
Saccharomyc
es, morchella
(morales)
Type of
Sexual
spore
Ascospore
Common
Name
Sac fungi
Habitats
Soil,
decaying
plant material
Common
deases
Dutch elm,
chesnut
blight, ergot,
rots
Group
Ascomycetes
Hyphae
Septate
Amanita
(poisonous
mushroom),
Agaricus
(edible
Soil,
decaying
plant material
Blact stem,
wheat rust,
corn smut
Basidiomycet es
Club fungi,
mushrooms
Septate
Basidiospore
mushroom)
Food
Mucor,
Rhizopus
(common
bread mold)
spoilage;
rarely
involved in
parasitic
Soil,
decaying
plant material
Bread
molds
Coenocy
tic
Zygomycetes
Zygospore
deseases

39. Eukaryotic Microbial Diversity
Characteristics and major properties of fungi
Typical
representati
ves
Type of
Sexual
spore
Common
Name
Habitats
Common
deases
Group
Hyphae
Potato
Water
molds
Coenocy
tic
blight,
certain fish
Oomycetes
Allomyces
Oospore
Aquatic
deseases
Plant wilt,
infections of
animals
such as
ringworm,
athlete’s
foot, surface
of systemic
infections
Soil,
decaying
plant
material,
surfaces of
animal
bodies
Penicillium,
Aspergillus,
Candida
Deuteromyce
tes
Fungi
imperfecti
Septate
None known
(Candida)
Eukaryotic Microbial Diversity

40. Macroscopic Fungi: Mushrooms
• Mushrooms are filamentous basidiomycetes that
form large fruiting bodies.
• During most of its existence, the mushroom fungus
lives as a simple mycelium, growing in soil, leaf litter,
or decaying logs. However, when environmental
condition are favorable, usually following periods of
wet and cool weather, the fruiting body develops.
• Sexual spores, called basidiospores are formed,
borne on the underside of the fruiting body on flat
plates called gills.
Eukaryotic Microbial Diversity

41. a b c
(a) Amanita, a highly poisonous mushroom. (b) Gills on the underside
of the mushroom fruiting bodycontain the spore-bearing basidia. (c )
Scanning
electron
micrograph
of basidiospores
released from
mushroom basidia.
Eukaryotic Microbial Diversity

42. Life cycle of a typical mushroom
Eukaryotic Microbial Diversity

43. Unicellular Fungi: Yeasts
• The yeasts are unicellular fungi, and most of
them belong to Ascomycetes.
• Yeast cells are typically spherical, oval, or
cylindrical, and cell division typically takes place
by budding.
• In the budding process, a new cell forms as a
small outgrowth of the old cell; the bud gradually
enlarges and then separates.
• Yeast flourish in habitats where sugars are
present, such as fruits, flowers, and the bark of
trees.
• The most important commercial yeast are the
baker’s and brewer’s yeasts, which are members
of the genus Sacharomyces.
Sacharomyces
cerevisiae
Eukaryotic Microbial Diversity

44. Algae • Alga are phototrophic Eukarya that contain
chlorophyll and caretenoid pigments within a
structure called chloroplast. The chloroplasts itself
has its roots in the domain bacteria.
• Most algae are either unicellular or colonial, the later
existing as aggregates of cells. When the cells are
arranged end-to-end, the algae is said to be
filamentous.
Eukaryotic Microbial Diversity

45. Properties of major group of algae
Typical
representa
tives
Chlamydom
onas
Euglena
Gonyaulax
Nitzschia
Carbon
reserve
materials
Starch
Paramylon
Strach
Lipids
Common
Name
Green
algae
Euglenoid s
Dinoflagell
ates
Golden-
brown
algae,
diatoms
Cell wall
cellulose
No wall
present
Cellulose
Two
overlapping
components
made of
silica
Major
habitats
Fresh water,
soils, a few
marine
a few marine
Mainly
marine, soil
Algal Group
Chlorophyta
Euglenophyta
Dinoflagellata
Chrysophyta
Morphology
Unicellular to
leafy
Unicellular,
flagellated
Unicellular

46. Eukaryotic Microbial Diversity
Properties of major group of algae
Typical
representati
ves
Carbon
reserve
materials
Common
Name
Cell wall
Major
habitats
Algal Group
Morphology
Filamentous
to leafy,
occasionally
massive and
Borwn
algae
Phaeophyta
Laminaria
Lammarin
Cellulose
Marine
plantlike
Unicellular,
Filamentous
to leafy
Floridean
starch
Rhodophyta
Red algae
Polysiphonia
Cellulose
Marine
Eukaryotic Microbial Diversity

47. b d a c
(a) Micrasterias, a single cell. (b) Volvox colony, containing a large
number of cells. (c) Scenedesmus. A packet of four cells. (d) Sirogyra. A
filamentous algae.

48. Euglena
Polysiphonia, a
marine red alga
Frustule of the
marine diatom
Nitschia
Frustule of the
marine diatom
Thalassiosira
Frustule of the
marine diatom
Asteriolampra
Cell of the marine
dinoflagellate,
Ornithocercus
magnificus

49. Toxic dinoflagellates. (a) “a red tide” caused by
massive growth of toxin-producing dinoflagellates,
such as Gonyaulax. Toxin excreted into the water
and also accumulates in shelfih that feed on the
dinoflagellates. (b) A toxic spores of P. piscicida.
(c) Fish killed by P. piscicida c
Eukaryotic Microbial Diversity

50. Endholitic (grow inside of
rocks) Cyanobacteria.
Photograph of a limestone rock
from Makhtesh Gadol, Negev
Desert, Israel, showing a layer
of cells of the cyanobacterium
Chroococcidiopsis
Photomicrograph of cells of
Chroococcidiopsis isolated
from a sandstonerock in
the Negev Desert.