Survey of Microorganisms
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6.
Virus
Bacteria
Cyanobacteria
Algae
Fungi
protozoa
VIRUS
– Obligated intracellular parasite.
– host specific:
 bacteriophage
 animal virus
 plant virus
– according to its genetic material
 DNA virus
 RNA virus
– Shape:
Most common shape is icosahedral , some are helical shape
– Structure:
Protein capsid and genetic material some animal virus have
envelope with glycoprotein spikes
– Life cycle: lytic infection lysogenic infection
– Some animal virus are closely associated with
certain cancers
Comparison of naked and
enveloped viruses
The replication cycle of
a bacterial virus(1)
The replication cycle of
a bacterial virus(2)
The replication cycle of
a bacterial virus(3)
Consequences of infection by
a temperate bacteriophage
Quantification of a bacterial
virus by plaque assay
Viral genomes
Plus/minus strand designation
Formation of mRNA
by different types of viruses
Rolling circle replication of
bacteriophage lambda
Shapes and relative sizes of
vertebrate viruses(1)
Shapes and relative sizes of
vertebrate viruses(2)
Possible effects of animals
virus infection on cells
Retrovirus structure and function(1)
Replication process of
a retroviruses(1)
Replication process of
a retroviruses(2)
Retrovirus structure and function(2)
Retrovirus Gene Structure
 Gag
: group antigens
 Pol : Reverse Transcriptase
 Env : Envelope
 Src : Code for Protein Kinase,
responsible for the malignant
transformation
Onc: Oncogen is analogous to the
Src gene - induce transformation
DNA tumor virus
1. Epstein Bar Virus – Burkitt’s
Lymphoma
Nasopharyngeal carcinoma
2. Herpes Simplex type 2 – carcinoma of
uterine cervix
3. Papilloma virus – uterine cervix
4. Hepatitis B – liver carcinoma
Taxonomy (1)

1. Species: Organism sharing a set of
biological traits and reproducing only their
exact kind. (Species is the fundamental unit
in taxonomy)
a. strain: organisms within the species varying
in a given quality
b. types: organisms within the species varying
immunologically.
2. Genus: closely related species
3. Family : closely related genera
Taxonomy (2)

4. Order: closely related families
 5. Class : closely related order
 6. Phylum: related classes
Use nutritional patterns, as well as structure ones
and biochemical properties, provide guidelines
for classification of microorganisms. E.g..
Autotrophy, heterotopy, oxygen requirement
etc.
Superkingdom
Kingdom
Prokaryotes
Monera
Bacteria
Cyanobacteria
Internal cell structure (1)
Superkingdom
Eukaryotes
Kingdom
Protista
Branch
protophyta
(Plant like protist)
algae
Branch
protomycota
(fungus like protists)
slime mold
Branch
Protozoa
(animal like protists)
amoeba
Internal cell structure (2)
The electron micrographs of
representatives
Kingdom
Fungi
Kingdom
Plantae
Kingdom
Animalia
Archaebacteria
It is a procaryotes, different from bacteria.
1.
2.
Cell Membrane
Form lipid monolayer instead of lipid bilayer (in
methanogens and thermophilic archaebacteria)
Cell Wall
Archaebacteria has no muramic acid and D-amino
acids.
Had pseudopeptidoglycan (use N-acetylglucosamine
and N-acetyltalosaminuronic acid).
Most of them are thermphile or halophilic, or
methanogens. Anaerobic.
Summary of major differentiating features between
eubacteria, archaebacteria and eucaryotes
Characteristics Eubacteria Archaebacteria
Eucaryotes
1.
Membranebound
nucleus
absent
absent
present
2.
Cell wall
Muramic acid
No Muramic acid
No Muramic acid
3.
Membrane lipids
ester linked
ether linked
ester linked
4.
Ribosome
70S
70S
80S
5.
RNA polymerase
One (4 sub)
Several (8-12 sub)
3 (12-14 sub)
BACTERIA
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Typical prokaryotes.
– Three shapes: cocci, bacilli and spiral
– Can be autotroph or heterotroph
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Autotroph: photoautotroph or chemoautotroph
Heterotroph: parasite or saprophyte
– According to Gram stain: G+ or G-
– Type of reproduction: binary fission
– Some genetic material transfer:
–
transformation, transduction and conjugation
Bacterial morphologies (1)
Bacterial morphologies (2)
Bacterial morphologies (3)
Bacterial morphologies (4)
The genetic map of the
F-plasmid
Cyanobacteria
– Blue green algae, in both fresh and marine water.
– A typical procayrotic living organism
– Autotroph, photosynthesis machinery is very similar to
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higher plants.
No chloroplast, have chlorophyll and other pigments
such as phycocyanin, phycoerythrin, carotene etc.
Three forms: unicellular, colonial and filaments.
Some filament cyanobacteria have heterocyst that can
fix N2 to ammonia.
e.g. Anacystis , Oscillatoria
Fungi
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Eucaryotic living organisms
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Heterotroph
(1) unicellular yeast
(2) muticellular molds
(1) Yeast
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Reproduction:
Budding processes (asexual reproduction) forming
buds on the mother cell when mature, punch off to
become new single yeast cells. sex spores (sexual
reproduction), produce sex spores following the
fusion of two separate cells.
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Many yeast convert carbohydrates to alcohol
for alcoholic beverages (e.g. Saccharomyces
cerevisiae)
Some are used to raise bread (produce CO2 in
the dough)
Multicellular fungi
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More complex than yeast, many of them
become visible as “mildew” in damp weather.
have hair like structure (mycelium)
Sexual and asexual reproduction
Some mold are responsible for the flavor of
fine cheeses.
Major sources of antibiotics
e.g. Penicillium chrysogenum for penicillin
Slim Mold (lower fungi)
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This is a lower fungi, in Protista and
protomycota.
It is similar to fungi, but distinct.
Heterotroph.
They live in cool, shady moist places in
nature - on decaying wood, dead leaves or
other damp organic matter.
Algae
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Eucaryotic living organisms
Autotroph:
Carry out a green plant type of photosynthesis
resulting in the photolysis of water and the evolution
of O2.
Mainly aquatic in nature.
Some of the primitive ones are classified in protista;
complex multicellular types are placed in plant
kingdom.
Three forms: unicellular, filaments and colonial.
7 classes on the basis of their cellular structure,
pigment composition. Only five will be discussed in
here and differentiate them using food storage
particles.
e.g. euglena, spirogyra and cladophora.
Algae
1.
Euglenoids
eg. Euglena
food storage is a lipoid polysaccharide - paramylum
2.
Green algae
eg. Chlamydomonas
food storage - starch
3.
Golden Brown algae
eg. Diatoms
food storage – oil and leucosin (a polysaccharide)
have fucoxanthin, a brownish pigment
4.
Brown Algae
Mainly marine water algae
food storage – laminarin, a polysaccharide and mannitol, a sugar alcohol
5.
Fire Algae
Dinoflagellate
eg. Peridinium
food storage – starch, fat, oils
Protozoa
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Unicellular, heterotroph
Animal like, move, they are either free
living or parasites.
A wide variety of shapes and sizes
some elongated, some are oval.
Sizes: from 5-10 um to 1-2 mm.
Sexual or asexual reproduction
e.g. amoebas, paramecium
Protozoa
Asexually some exhibit sexual reproduction. Cyst, enables them
to survive drought, heat and freezing.
Three Phyla:
1. Sarcomastigophora
subphyla Sarcodina
Pseudopods
eg. Amoeba
Mastigophora Zooflagellates eg. Heteronema
2. Ciliophora: most advanced and structurally complex of protozoa.
eg. Paramecium, Blepharisma, Stentor
3. Sporazoa
internal parasites eg. Plasmodium, the malarial parasite.