Morphology of Bacteria Size, shape, arrangement, patterns of arrangement

1. Prokaryotic and Eucaryotic
Cell Structures

2. Morphology of Bacteria
A. Size
- bacterial cells vary in size depending on the species,
but most are approximately 0.5 to 1 um in diameter or
width
e.g. Staphylococci and streptococci (D=0.75 to 1.25 um)
cylindrical typhoid and dysentery bacteria (0.5 um to
1 um in width and 2 to 3 um in length)

3. B. Shape
-divided on three main groups:
1. Cocci – spherical* (eg. S. aureus)
2. Bacilli – cylindrical or rod-shaped*(eg. B. subtilis)
3. Spirilla- spirals* (Treponema)
4. comma-shaped (eg. Vibrio cholerae)
*Usually round but they can be ovoid or flattened on 1 side
when they are adhering to another cell
*have considerable differences in length and width for the
various species. The ends of some are square, others
rounded, or tapered or pointed.
*helical bacteria that look like corkscrews (e.g. Spirochetes)
Pleomorphic- can have variety of cell shapes
e.g. Arthrobacter (it changes its shape as the culture
ages)

4. C. Arrangement
Examples:
a. Neisseria
b. Streptococcus species
which cause throat and
wound infection
c. Pediococcus
d. Staphylococcus
e. Sarcina

5. Patterns of arrangement
Examples
a. Corynebacterium diphtheriae
b. Caulobacter
c. Streptobacillus

7. Bacterial Cell Structure
1. Appendages – flagella and pili
2. Surface Layers- capsule, cell wall and plasma
membranes, mesosomes
3. Cytoplasm – nuclear material, plasmids, ribosomes,
inclusions and chromatophores
4. Special structures

8. Flagella (singular, flagellum)
-thin, hairlike filaments extend from the cytoplasmic
membrane and through the cell wall
-propel bacteria through liquid sometimes as fast as
100 um per second (= to 3000 body lengths/min)
-composed of three parts:
1. basal body
2. a short hooklike structure
3. a long helical filament
L ring
P ring
Rod
S ring
M ring
Gram-negative
(E. coli)

9. -but for Gram positive bacteria like Bacillus subtilis, their
flagellum lacks the L and P rings since they have no outer
membrane
*the rings of the basal body, through chemical reactions, rotate
the flagellum (proton motive force)
-the hooks positions the filament in such a way that the helical
filaments spins evenly about its long axis instead of
rotating off center
-the filament is composed of protein molecules called flagellin
(made within the cell and then passed along the hollow core of
flagellum to be added to the distal end of the filament.)
thus a flagellum grows at its tip rather than at its base

10. -flagella are usually several times longer than the cell
(15 to 20 um in length but diameter is 12 to 20 nm)
-cocci have no flagella but for bacteria that do, the pattern
of flagellar attachment and the number of flagella are used
to classify them into taxonomic groups

11. Pseudomonas
Some pseudomonads
spirilla
Escherichia

12. Periplasmic flagella
-also known as axial filament
-special flagella that arise at
the cell poles and wind
around the cell body or
protoplasmic cylinder
beneath the outer mem-
brane of the cell wall
-responsible for the corkscrew-
like motility of the
spirochetes

13. Chemotaxis
- the movement of bacteria in response to chemicals
in the environment
*attractant – towards
*repellant – away
Polar flagellated bacteria (swim in back- and- forth fashion)
-reverse their direction by reversing the direction of
flagellar rotation
Peritrichous flagellated bacteria swim in a very complicated
manner (the cell swims along a relatively straight
track called a run, when the flagellar motors reverse,
the bundle of flagella flies apart and the cell tumbles
wildly)

18. The following players are involved in chemotaxis:
MCP: methyl accepting chemotaxis proteins respond
to repellent in fully methylated state
CheW : Coupling protein between MCP and CheA
CheA : Is a sensor kinase autophosphorylates itself
and CheY apart from CheB
CheY: Acts as response regulator and in
phosphorylated state moves to motor of flagella and
rotates it clockwise.
CheB: Acts as demethylase in phosphorylated form
CheR: Acts as methyl transferase , transfers methyl
group to MCP
CheZ: Dephosphorylates CheY

20. Fig. 5 - Phosphorelay signaling. The flagellar motors of E. coli spin CCW by
default; the signaling pathway modulates the level of phospho-CheY, the signal for
CW rotation. Reactions and components that augment CW rotation are depicted in
green; those that augment CCW rotation are depicted in red.

21. Quiz

23. http://www.rowland.org/labs/bacteria/movi
es/rsphe_f_swim_1.mov
Movfluorescent ie of motile Rhodobacter
spheroides with labelled-flagella

24. Fimbriae and Pili
- found in gram-negative bacteria
-shorter, straighter and more numerous than
flagella
-not for motility
-are hollow like flagella but nonhelical
-thinner (3 to 10 nm in diam)
Fimbria
- belong to a class of proteins called lectins
which recognize and bind to specific sugar resi-
dues in cell surface polysaccharides)
-frequently called adhesins (bacteria
possessing fimbriae have a tendency to adhere
to each other as well as to animal cells)

26. N. gonorrhoeae and enterotoxigenic E.coli
-ability of certain organisms to cause
disease is associated with the possession
of fimbriae (loss of fimbriae is accompanied
by a loss of virulence)
Pilus or Pili
-morphologically and chemically similar to
fimbriae
-involved in sexual reproduction of bacteria
(F pilus)
*those with F pilus are donor cells and
those without it are recipient cells
(genetic materials are transferred during
bacterial conjugation)

27. Glycocalyx
- a layer of viscous material that surrounds
some bacterial cells
- special stains are used to show this layer
such as India ink (appears halo under a light
microscope)
-composed of polymers
a. Capsule – if the glycocalyx is organized
into a defined structure and is attached
firmly to the cell wall
b. Slime layer- if the glycocalyx is disorganized
and without any definite shape
-attached loosely to the wall
-tends to be soluble in water
-medium becomes highly viscous
-produce stringiness in milk

28. Capsules maybe:
1. Homopolysaccharide
-single kind of sugar
-synthesis of glucan from sucrose by
Streptococcus mutans
-to adhere firmly to smooth tooth
surfaces and cause dental caries or
cavities (without the sticky glucan, the
microorganisms might be swept away
by flowing saliva)
2. Heteropolysaccharide
-more than one kind of sugar
-capsule of S. pneumoniae , type VI,
consists of galactose, glucose &
rhamnose

29. *few capsules are made of polypeptides
(e.g. Capsule of Bacillus anthracis, made
entirely of a polymer of the amino acid glutamic
acid; more of the rare D optical isomer rather
than L isomer usually found in nature)
Glycocalyx
-serve a number of functions (depending on
the bacterial species)
1. adherence to various surfaces (major role)
such as rocks in fast-moving water,
plant roots and human teeth
2. capsules protect from temporary drying by
binding water molecules
3. serve as a reservoir of stored food

30. 4. Capsules may prevent attachment and
lysis of cells by bacteriophages(viruses
that attack bacteria)
5. Capsules protect pathogenic from being
engulfed by the white blood cells that
defend the mammalian body
6. Nuisance to industry (responsible for
accumulation of slime in manufacturing
equipment that can clog filters and coat
pipes affecting the quality of the final
product)

31. The Cell Wall of Prokaryotes:
Peptidoglycan and Related
Molecules

32. peptidoglycan
Cytoplasmic
membrane
Outer membrane
peptidoglycan
Gram + Gram -
Cytoplasmic
membrane
Cell wall
Cell wall
15-80 nm
7-8 nm
7-8 nm
2-3 nm
Schematic cross sections of bacterial cell wall
Typical lipid-protein bilayer

35. Bacterial cell wall
- fundamental differences in ultrastructure of
the cell wall are responsible for the reaction
(+ or -) of bacteria towards the Gram stain.
- In both types of cell, the cytoplasmic
membrane is surrounded and supported by
a cell wall, which provides strength, rigidity
and shape. (prevents cell from expanding
and eventually bursting bec of water
uptake)

36. -Usually essential for cells to grow and divide
(cells whose walls have been removed in the
laboratory are incapable of normal growth and
division)
-Account for as much as 10 to 40% of the dry
weight of the cell depending on the species
and the cultural conditions

37. • This material consists of strands of
alternating repeats of N-acetylglucosamine
and N-acetylmuramic acid, with the latter
cross-linked between strands by short
peptides. Many sheets of peptidoglycan can
be present, depending on the organism.

39. Each peptidoglycan repeating subunit is
composed of four amino acids (L-alanine, D-
alanine, D-glutamic acid, and either lysine or
diaminopimelic acid) and two N-acetyl-
glucose-like sugars

42. • Archaea lack peptidoglycan but contain walls
made of other polysaccharides or protein. The
enzyme lysozyme destroys peptidoglycan,
leading to cell lysis.

43. Peptidoglycans
• Alias murein or mucopeptide
• Present in almost all bacteria (exceptions: wall-
less mycoplasmas; archaebacteria)
• Unique to bacteria
• Essential function
(physical support of the
cytoplasmic membrane)
• Common architecture
but variations in
structural detail
• Ideal target for
selective toxicity
• contains 3 kinds of
building blocks
1 2
3
(tetrapeptide)

45. Gram-positive
• Relatively thick and featureless (electron
microscope)
• Major component (~50%) is peptidoglycan
• No lipid and often no protein
• Accessory polymers (teichoic acid and/or
teichuronic acid) covalently linked to
Peptidoglycan or to cell membrane

46. 2 major forms of teichoic acid
1. polymers of ribitol phosphates
2. polymers of glycerol
-aid in the transport of positive ions in
and out of cell
-aid in the storage of phosphorus
-highly antigenic(i.e. They will induce a
host to make specific antibodies); provide the
antigenic determinants used in the serological
identification of many groups and species of
gram-positive bacteria

48. Gram-negative
• The cell envelope consists of a pair of membranes
(cytoplasmic and outer) with a thin, intermediate
layer of peptidoglycan
• the outer membrane not the peptidoglycan that
distinguishes the Gram- bacteria
• The outer membrane contains lipopolysaccharide
(LPS) as well as lipids and proteins (lipoprotein). LPS
is located exclusively in the outer leaflet: lipid
embedded in the membrane, polysaccharide
protruding.

52. Lipopolysaccharides (LPSs)
-characteristic of gram negative bacteria
(gram+ bacteria ,cell wall has no LPS)
-composed of 3 covalently linked
segments:
1. Lipid A - firmly embedded in the
membrane
- extremely important bec of its
toxicity to animals (also)
known as an endotoxin and can
act as a poison-causing fever,

53. diarrhea, destruction of red blood cells and potentially
fatal shock.
- Unlike lipids in CM, lipid A is not composed of
phospholipids but of saturated fatty acids
2. Core polysaccharide
- located at the membrane surface
3. O antigens
- polysaccharides that extend like whiskers from
the membrane surface to the surrounding medium
-consists of repeating carbohydrate units
arranged in a variety of combinations

54. -carbohydrates include common hexoses(glu,gal,
mannose and rhamnose) and some unique sugars
(abequose)
-responsible for many of serological properties of LPS-
containing bacteria
-they also serve as sites for bacteriophage attachment
to bacterial cells

55. *the outer membrane is selectively permeable to
molecules on the basis of their electric charge
and molecular size
Porins –diffusion channels formed by special proteins
where molecules pass
•The general designation for outer –membrane
proteins including porins and receptors is
Omp.
Removal of peptidoglycan layer in the presence of 10-20% sucrose , the cell
with CM is
called: spheroplast - Gram-negative bacteria
protoplast – Gram-positive bacteria

56. Cell Wall

58. Cytoplasmic Membrane: Structure

60. Cytoplasmic Membranes
-immediately beneath the cell wall
- in aerobic organisms, it transports electrons and
protons released during oxidation of bacterial
“foodstuffs” to oxygen (to form water) & it converts
the energy liberated by such oxidations into
chemical E that can
be used by the cell
-it contains some of the enzymes necessary for
the synthesis and transport of peptidoglycan,
teichoic acids and outer membrane compts.

61. -it secretes extracellular hydrolytic
enzymes
- it ensures the segregation of nuclear matl
(DNA) to daughter cells during division
- it controls the transport of most
compounds entering and leaving the cell

63. Unlike Bacteria and Eukarya, in which ester linkages
bond fatty acids to glycerol, Archaea contain ether-
linked lipids.

64. Structure and Chemical Composition of CM
-approx 7.5 nm thick
-composed of phospholipid (20-30%) and
proteins (50-70%)
-fluid-mosaic model
-semipermeable
-contains specific proteins called permeases

68. -most prokaryotic CM do not contain sterols such as
cholesterol (less rigid than those of eucaryotes)
-an exception is the mycoplasmas (w/out cell walls),
Thus the cytoplasmic membrane is the outermost
structure of a mycoplasma cell and the sterols in mem-
brane help the cell to maintain its integrity
-since do not have membrane-bounded organelles, the
CM of many bacteria extend into the cytoplasm to form
tubules known as Mesosomes
-prominent in gram-positive bacteria
-consists of 2 types:
1. central –fd deeper, seem to be attached to cell’s nuclear
material (thought to be involved in DNA replication
and cell division)
2. peripheral- barely penetrate the CM; not restricted to
central location;not associated w/ nuclear material
- appear to be involved in the secretion of certain
enzymes such as penicillinases that destroy penicillin

70. -diffusion and osmosis occurs across the cytoplasmic
membrane
Internal Cell Structures
-material contained wiithin the cytoplasmic membrane
may be divided into:
1. the cytoplasmic area – the fluid portion contg. dissol-
ved substances and particles such as ribosomes
2. nuclear material or nucleoid –rich in the genetic
material DNA
Cytoplasmic area
-consists of of about 80% water
-aside from water, NA, proteins, CHO, lipids, inorganic
ions, many low-mol weight cpds and particles w/
various functions
- no evidence that it has cytoskeleton unlike in
eukaryotes

71. Ribosomes
-densely packed in the cytoplasm
-site of protein synthesis
-consist of two subunits:
a. 50S subunit
b. 30S subunit 70S ribosome
-targets of many antibiotics that inhibit protein
synthesis such as strptomycin, neomycin, tetracyclins
Inclusions
-chemical substances that accumulate and form
insoluble deposits in the cytoplasm
-these may be granules of various kinds:
a. Glycogen-look like dark granules
b. Polyhydroxybutyrate (PHB)droplets –acts a
reserve carbon and energy source (clear, round
areas)

72. Cytoplasmic inclusions Where found Composition Function
glycogen
many bacteria e.g. E.
coli
polyglucose
reserve carbon and
energy source
polybetahydroxyutyric
acid (PHB)
many bacteria e.g.
Pseudomonas
polymerized hydroxy
butyrate
reserve carbon and
energy source
polyphosphate (volutin
granules)
many bacteria e.g.
Corynebacterium
linear or cyclical
polymers of PO4
reserve phosphate;
possibly a reserve of
high energy phosphate
sulfur globules
phototrophic purple
and green sulfur
bacteria and
lithotrophic colorless
sulfur bacteria
elemental sulfur
reserve of electrons
(reducing source) in
phototrophs; reserve
energy source in
lithotrophs
gas vesicles
aquatic bacteria
especially
cyanobacteria
protein hulls or shells
inflated with gases
buoyancy (floatation)
in the vertical water
column
parasporal crystals
endospore-forming
bacilli (genus Bacillus)
protein
unknown but toxic to
certain insects
magnetosomes certain aquatic bacteria
magnetite (iron oxide)
Fe3O4
orienting and
migrating along geo-
magnetic field lines
carboxysomes
many autotrophic
bacteria
enzymes for
autotrophic CO2
fixation
site of CO2 fixation
phycobilisomes cyanobacteria phycobiliproteins
light-harvesting
pigments
chlorosomes Green bacteria
lipid and protein and
bacteriochlorophyll
light-harvesting
pigments and antennae
Table 8. Some inclusions in bacterial cells.

73. c. Sulfur globules – found in H2S-oxidizing bacteria
d. Volutin granules (metachromatic granules)-made of
polyphosphates
-reddish color when stained with methylene
blue
-appear round
Chromatophores
-special membrane system found in certain
photosyhnthetic bacteria and cyanobacteria
-lacks chloroplasts
Nuclear area
-lacks nucleus
-nuclear matl in a bacterial cell occupies a position
near the center of the cell

74. Sulfur globule

75. Figure 3. A variety of bacterial inclusions. a. PHB
granules; b. a parasporal BT crystal in the sporangium of
Bacillus thuringiensis; c. carboxysomes in Anabaena
viriabilis, showing their polyhedral shape; d. sulfur
globules in the cytoplasm of Beggiatoa.

76. -seems to be attached to the mesosome-cytoplasmic
membrane system
-total nuclear material called the nucleoid consists of a
single, circular chromosome
Plasmids
-relatively small, circular pieces of double-stranded
DNA which exist separately from the bacterial
chromosome
- capable of autonomous replication and encode
for many auxiliary functions (antibiotic resistance) not
necessary for bacterial growth
-can be transferred from 1 bacterium to another thru
conjugation or thru lab manipulation. (recombinant
DNA technology)

78. Dormant Forms of Prokaryotic Microorganisms
-some species of bacteria produce dormant forms
called: spores and cysts
-can survive unfavorable conditions such as drying
or heat
-resting forms (metabolically inactive) but in favora-
ble conditions they can germinate and become
metabolically active vegetative cells (grow and
multiply)
Spores
-only two genera of medical importance, Bacillus and
Clostridium have the ability to developed specialized struc-
tures called endospore.
-form within the cell
-thick-walled, highly refractile and highly resistant to
environmental changes

79. -when endospores are freed from the mother cell or
sporangium, they can survive extreme heat, drying,
and exposure to toxic chemicals such as disinfectants
eg. C. botulinum –cause of food poisoning (botulism)
can resist boiling for several hours
Vegetative cells-killed at 70C but most endospores w/stand
80C for at least 10 min
-endospores contain large amts of dipicolinic acid (DPA)
-a unique compound not found in vegetative cells that
may play a role in heat resistance
-5-10% dry weight of spore and occurs in combn w/
Ca
Conidium
-another type of spore produced by Actinomycetes

80. -not much more heat-resistant than vegetative cell tho
resistant to drying
-produce many of these conidia at the tip of a filament
-for reproduction not for protection
Cyst
-like endospores, they are dormant
-thick-walled forms that resist drying
-develop frm vegetative cell
-structure and composition different from
endospres and do not have high heat of resistance
eg. Cyst produced by Azotobacter

83. Endospore Formation

84. Gross Morphological Characteristics of
Eukaryotic Microorganisms

86. Morphology of Fungi
-yeasts and molds
- differ in their morphology
Yeast
-single yeast cells are generally larger than most
bacteria (size: 1-5 um in width and 5-30 um or
more in length)
-commonly oval, but some are elongated or
spherical
-each species has a characteristic shape
-variation in size and shape of individual cells
-lack flagella and other means of locomotion
-on agar medium, form smooth, glistening colonies
that resemble those of bacteria

89. Molds
-multicellular organisms that look like filaments under low
magnification
-with high magnification, they look like tiny jungles
-the body (thallus)
-consists of the mycelium (mycelia) and dormant
spores
-each mycelium is a mass of filaments called hyphae
Hypha
-about 5-10 um in width and is formed by joining to-
gether of many cells
-rigid walls of hyphae are made of chitins, celluloses
and glucans
-maybe classified as
1. coenocytic –do not have septa(crosswalls bet the
cells that make up a long filament)
-contains many nuclei

90. 2. septate – have septa that divide the filaments into
distinct cells containing nuclei
*there is a pore in each septum that allows cytoplasm and
nuclei to migrate between cells
•A hypha grows by elongation at its tip and each fragment
that contains nuclei is capable of growing into a new
organism
-some hyphae are embedded in solid media such as
bread or soil to give the thallus support and nourishment
(rhizoids-specialized hyphae since they are rootlike)
Reproductive hyphae may grow upward into the air to disse-
minate the spores they produce.
Vegetative hyphae- hyphae with no specialized division of
labor may simply grow along the surface of the substrate

91. Germ tube
-a short, hyphalike
extension that soon
Grows into a thallus

92. -other hyphae can become organized into large structures
to form the so called fleshy fungi, such as mushrooms,
puffballs, and bracket fungi.
•Many fungi exhibit dimorphism (existing either in a unice-
llular, yeastlike form or in a filamentous form)
Present when the
organism is parasite
When the organism is a
saprophyte in its natural
habitat (such as soil) or on
lab media incubated at rm T

94. Morphology of Algae
- are of many sizes and shapes
-species range from single microscopic cells to orgs
hundreds of feet long
-Single –celled species may be:
1. spherical
2. rod-shaped
3. club-shaped
4. spindle-shaped
-some maybe motile
-Multicellular
-some organized as filaments of cells attached end to end
-in some species these filaments intertwine into microscopic
plantlike bodies
-occur in colonies, some of which are simple aggregations of
single cells, while others contain different cell types with
special functions

97. Morphology of Protozoa
-some are oval or spherical, others are elongated
-others are polymorphic, w/ morphologically different
forms at diff. stages of life cycle
-cells can be as small as 1 um in diameter and as large
as 2000 um or 2 mm)
-like animals, protozoa lack cell walls
-able to move at some stage of their life cycle
-ingest particles of food
-each individual cell is a complete organism
*many protozooan cells are more complex than other
types of cells

98. Protist Cell
arrangement
Mode of
nutrition
Motility Miscellaneo
us
Fungi unicellular Chemoheterotr
ophic by
absorption of
soluble
nutrients
nonmotile Sexual and
asexual spores
Algae Unicellular or
multicellular
Photoautotrop
hic by
absorption of
soluble
nutrients
Mostly
nonmotile
Photosynthetic
pigments
Protozoa unicellular Chemoheterotr
ophic by
absorption or
ingestion of
particles of
food
Mostly motile Some form
cyst
Major Distinguishing Characteristics of the Eucaryotic Protists

99. Ultrastructure of Eucaryotic microorganisms
Flagella and Cilia
-thin structures for locomotion
-originate from a basal body lying beneath a mem-
brane that encloses the cell
-many single-celled protozoa and algae possess
flagella(beat with a whiplike motion and propel the
cell through fluid environments
*in some cases, only the presence of chlorophyll
distinguishes a motile alga from a protozoan
-both cilia and flagella are identical in structure but
cilia are usually shorter and numerous (arranged in
groups or rows on the cell surface)
-cilia beat in a coordinated rhythmic motion

100. -structurally and functionally more complex
than procaryotic flagella and cilia
-composed of thin, hairlike
microtubules: “9 + 2” arrangement (9 pairs
of these tubules encircle a central pair )
-shaft formed by the microtubules
Is wrapped in a membrane
Differences bet eucaryotic and procaryo
-tic flagella
1. movement is powered by the
hydrolysis of the chemical cpd
ATP for the eucaryotes while for
procaryotic flagella, the energy to
move it comes from the proton
motive force(the movement of
hydrogen ions across the CM)

101. 2. Differ also in the way they move the cell
*eucaryotic flagellum-propels the cell by acting
like a whip, bending and twisting against the
liquid environment
*procaryotic flagellum-moves the cell by rotating
like a corkscrew
Pseudopodia
-specialized structures as mode of locomotion by
some protozoans

102. Amoeba in motion - YouTube

103. -a pseudopodium is a temporary projection of part of
the cytoplasm and cytoplasmic membrane which is caused
by cytoplasmic streaming
-characteristics of amoebas
-maybe used to capture food particles
Cell Walls
-plants, algae and fungi have cell walls
-maintains the shape of cells and prevents them from
bursting through osmotic pressure
-cell walls of plants, algae, and fungi differ from one
another and from bacterial cell walls in chemical
composition and physical structure
-protozoa lack cell wall but some are surrounded by
a layer of shell-like matl (may fit tightly or form a
loose chamber in which the organism moves)
*scales or spines may be present

104. Organism Chem. composition
Plant Rigid; mainly polysaccharides
(cellulose and pectin)
Filamentous fungi Chitin and cellulose
Unicellular yeast Polysaccharide mannan (polymer of
the monosaccharide mannose)
algae Varying amounts of cellulose, other
polysaccharides and calcium
carbonate
Table 4. Differences in the cell wall compositions of eucaryotes
-the walls of diatoms (algae)
*impregnated with silica making them thick & rigid
*surfaces often delicately sculptured with intricate
designs characterictic of the species

105. Cytoplasmic membrane
-eucaryotes CM have sterols while that of
procaryotes generally does not
Cellular Organelles
-inside the the CM is the protoplasm
Protoplasm is divided into:
a. Karyoplasm- the material inside the nuclear
membrane
b. Cytoplasm- the material between the nuclear
membrane and CM.
-where organelles are found
-has cytoskeleton (network of microtubules
and proteins)
*provides shape and support
*serves as framework along which
organelles move thru the cytoplasm

106. Nucleus
- many protozoan have multiple nuclei thruout the
greater part of their life cyle.
- in ciliated microorganisms, there are two nuclei:
1. macronucleus- large nucleus
- controls metabolic activities, growth and
regeneration
2. micronucleus- small nucleus
- controls reproductive activities

107. Chloroplast
- algae have another energy-generating cytoplasmic
organelle
-site of photosynthetic reactions(light is used to con-
vert energy for the cell)
-a cucumber-shaped body (2 to 3 um wide, 5 to 10 um
long) surrounded by a double membrane
Stroma- the interior
- where DNA(circular, like procaryotic DNA)
codes for proteins on the chloroplast
ribosomes and for the enzymes needed
to use carbon dioxide from the air.
Thylakoids- stacks of disk-shaped or ribbonlike sacs
which contain the chlorophyll and caro-
tenoid pigments that function in photo-
synthesis
Grana- each stalk is called granum

109. Dormant Forms of Eucaryotic Microorganisms
-some microorganisms can produced dormant forms
called spores and cyts that can withstand unfavorable
conditions
-both fungi and protozoa use such resting structures
for protection and reproduction
-algae also form spores but their main function is for
reproduction. Algae do not form cyts.
Spores
-fungi produce both sexual and asexual spores
A. Sexual spores
-produced as a result of the fusion of two
specialized reproductive cells called gametes
into one fertilized cell.
-produced less frequently and in smaller numbers

113. B. Asexual spores
-does not involve the fusion of gametes
-each thallus can produce hundreds of thousands of
asexual spores, produced by aerial hyphae
-purpose is to dessiminate the species, and are
specially structured for dispersion from the mother
thallus
*spores of aquatic fungi-may be motile in water
*spores of soil fungi-may have thick coats to
withstand drying or may be light enough
to travel on air currents
-usually white when 1st produced but they turn a cha-
racteristic color with age.
-eg. Penicillium notatum-colonies blue-green
Aspergillus niger- black

115. Cysts
-resting forms produce by many protozoa
- 2 possible forms of protozoan cyts:
a. Protective cyst
b. Reproductive cyst
Trophozoites
-the vegetative forms of protozoa
-synthesize protective cysts that are resistant to drying,
lack of food, lack of oxygen, or acidity in the host’s
stomach. (when conditions once again become favora-
rable, cysts form trophozoites that feed and grow.
Reproductive cyst- not induced by adverse environmental
conditions
-often thin-walled and lack the resistance of protective
cysts

116. *parasitic species of protozoa often move from host to
host as cysts(mode of transmission)
-form in the intestinal tract and are excreted in
feces which contaminate water and food ingested
by next host.
*CYST is the only way to survive outside the host.
e.g. Giardia lamblia -causative agent of diarrhea
and abdominal cramps in humans
-transmitted to humans by cysts
in water supplies contaminated with feces

117. THANK YOU for listening!