Transcript Unit2 classification microorganismsnotes

Classification of
microorganisms and
functional anatomy of
prokatyotic
and eukaroytic cells
CLASSIFICATION OF
ORGANISMS
• 1735 - Linnaeus-Established first classification
system for classifying living things.
• Established the binomial*" system of
nomenclature for_-naming organisms.
• This means that each living organism is given a *
genus and species name.
• This is called the scientific name and MUST
always be written with the genus name first and
the species name second.
• The genus name must be capitalized
and the species name written in
lower case letters.
• The entire scientific name must be
either italicized or underlined.
Linaeus's classification system
was composed of 2 Kingdoms
• . A plant kingdom and an animal
kingdom.
• Microorganisms were considered so
unimportant that they were grouped
under a heading of Vermes in a
catagory Chaos.
 1969.Robert Whittaker-devised a
five-kingdom classification system
based on the 'cellular organization
and nutritional patterns of
organisms.
• In 1969, R. H. Whittaker
developed a 5 kingdom system
which included:
1. Plants
2. Animals
3. Protist
4. Fungi
5. Monera/ Prokaryotes
ALL CELLS ARE CLASSIFIED AS EITHER
PROKARYOTES OR EUKARYOTES
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PROKARYOTES - pro means primitive
DNA contains no protein .lack nucleus
no organelles
single chromosome composed of DNA in loop.
chlorophyll, if present, is in cytoplasm.
ribosomes are smaller and free in the cytoplasm.
cell usually surrounded by a cell wall.
Reproduce by fission: no evidence of mitosis
EXAMPLES - bacteria, rickettsiae, chlamydiae,
mycoplasms, cyanobacteria
EUKARYOTES - eu means
true
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have nucleus
have organelles (ex. mitochondria, lysosomes,
Golgi apparatus,
endoplasmic reticulum.
have multiple chromosomes in nucleus with
protein around chromosome
ribosomes bound to membrane or free in
cytoplasm. Larger.
chlorophyll, if present, is in organelle.
cell wall absent or less complex chemistry
reproduce by mitosis
EXAMPLE - fungi, protozoa, plants, animals
Cellular Components:
• Plastids- contains pigment
NUCLEUS
• double membrane
bound
contains chromatin
disappears during
mitosis or meiosis
when the
chromosomes
divide and is
reformed after
cytoplasmic
organelle
NUCLEOLUS
• Aka “little nucleus”
• Found in the nucleus
• Contains RNA and
proteins for ribosome
synthesis
CYTOPLASM
• gelatin-like inside cell membrane
• constantly flows
• It contains the various
organelles of the cell
ENDOPLASMIC RETICULUM
• extensive convoluted
membrane continuous
with the outer nuclear
membrane and enclosing
a continuous internal
space involved in the
synthesis and transport
of membrane proteins
and lipids and of
proteins destined for
secretion from the cell
ENDOPLASMIC RETICULUM
• A series of folded
membranes that move
materials (proteins)
around in a cell like a
conveyor belt
• Smooth ER – ribosomes
not attached to ER,
functions in lipid
synthesis
• Rough ER – ribosomes
attached to ER,
functions in producing
proteins
RIBOSOMES
• Make proteins
• Float freely or
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attached to the
endoplasmic
reticulum (ER)
Ribosomes are made
in the nucleolus and
are small particles of
RNA
MITOCHONDRIA
• Organelles that
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release energy
from food (power
house of cell)
This energy is
released by AKA
the powerhouse
b/c they release
energy (ATP) from
food
Folds of mitochodria are called:
GOLGI BODIES (GAWL jee)
• Stacked flattened
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membranes
Sort and package
proteins
LYSOSOMES (LI suh sohmz)
• The word "lysosome" is Latin for "kill
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body."
The purpose of the lysosome is to
digest things. They might be used to
digest food or break down the cell
when it dies.
Break down food molecules, cell wastes
& worn out cell parts
VACUOLES
• Temporary
storage spaces
• Store food,
water, waste
• may contain air,
water, cell sap,
partially digested
food etc...
Centrioles
• Short cylinder near nuclear envelope
• There generally are 2 at right angles
to each other
• They control cell division
Peroxisome• small organelle bounded by a single
membrane and containing
• catalase and peroxidases
• important in detoxification reactions
Cell Wall
• located beneath the capsule and external
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to the cytoplasmic membrane. All bacteria
except for mycoplasms have cell walls.
Functions:
A. Maintain shape of bacteria
B. Prevent cell from rupturing - internal
pressure 20 times external
pressure.
C. Point of anchorage for flagella
• The cell wall is composed of
peptidoglycan which is present either
alone or in combination with other
substances.
• The peptidoglycan is composed of a
carbohydrate backbone linked
together by peptides.
• Gram positive cell walls are
composed of a thick layer of
peptidoglycan approximately 25 nm
in thickness.
• Teiochoic acid is also present in the
peptidoglycan layer.
• The peptidoglycan makes up about
50% of the dry weight.
• Gram negative cell walls are composed of
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a thin layer of peptidoglycan
approximately 3 nm in thickness.
There is no teiochoic acid in the
peptidoglycan layer but there are layers of
lipopolysaccharide, phospholipids, and
lipoproteins outside the peptidoglycan
layer.
The peptidoglycan layer makes up about
10% of the dry weight.
• Penicillin - antibiotic that functions in
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preventing the formation of cell walls.
Works best on Gram + bacteria.
• Lysozyme - an enzyme found in body secretions
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that breaks down cell walls. Protoplast - a Gram
+ bacterium that has had the cell wall removed.
Made by treating cell with Lysozyme.
Spheroplast - a Gram - bacterium that has had
the peptidoglycan layer of the cell wall removed.
Still has the cell membrane with the lipid layers of
the cell wall on the outside.
Both protoplast and spheroplast will be spherical
regardless of their original shape.
CELL MEMBRANE
• approximately 7.5 nm thick and composed
of a phospholipid bilayer with proteins
dispersed throughout.
• The phospholipid bilayer is composed of
phosphates and glycerol on the outside
with tails of fatty acids on the inside.
• The polar heads are on the 2 outside
surfaces and the non-polar tails are on the
inside.
• The arrangement of phospholipids
and proteins is referred to as the
fluid mosaic model due to the
continuous change in the
arrangement of the molecules.
• Ethyl alcohol and poly myxin
destroys the membrane.
Functions:
1. selective barrier - membrane is
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selectively permeable
serves as anchor for attachment of DNA
site of enzymes that function in cell wall
synthesis (permeases)
site of enzymes that function in energy
production
secretes exoenzymes that break down
large molecules
MAJOR GROUPS OF
MICROORGANISMS
1. BACTERIA –
• unicellular, prokaryotic organisms that
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are among the most abundant on earth.
May be aerobic (requires oxygen)
anaerobic (Needs no oxygen), or
facultative (indifferent to oxygen, can
survive either way).
Multiply by binary fission (single
chromosome duplicates and 2
chromosomes move to different areas
and membranes grow inward).
Bacteria have 3 basic shapes –
a) coccus-round
b) bacillus -rod
c) spiral-curved shape called spirillum
• Some form endospores-cell shrinks,
rounds up within old membrane and
forms new thicker walls.
• Average size is one micrometer.
• BACTERIOLOGY-study of bacteria
Types of Bacteria
• Rickettsiae
• -small bacteria, among the tiniest microorganisms, usually
transmitted by arthropods. Grow and multiply only within
living cells. .5 urn. in size. Ex. Rocky Mountain Spotted
Fever 1 micrometer = 1 thousandth of a millimeter
• Chlamydiae
• -subgroup of Rickettsiae, among smallest Rickettsiae, .25
urn. Grow and multiply only in living cells. Ex. disease of
eye, lung, and urogenital tract.
• Mycoplasms
• smaller than Chlamydiae, .1 urn. Pleomorphic, has no cell
wall, can grow on artificial media if certain steroids are
added. Ex. walking pneumonia.
Types of Bacteria
• Cyanobacteria
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Known as blue-green algae. Nore
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closely related to bacteria because of
structural and biochemical properties.
Not true bacteria. Possesses lighttrapping pigments, many are blue but
some are black, red, yellow, or green.
Inhabit both fresh and salt water. Ex
makes swimming pools green.
2. Protozoans:
• Single celled eukaryotes that are usually
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microscopic.
Can cause parasitic diseases such as
malaria.
Some are capable of photosynthesis but
most are not.
They are classified according to their
locomotion ( flagella, cilia, pseudopods)
Protozoa average about 100um.
• Protozoology is the study of protozoas
3. FUNGI•
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eukaryotic, non-photosynthetic, and
contain chitin in their cell walls. Plants do
not have chitin in the cell walls. Aid
bacteria in decomposition.
Include yeast, molds, and mushrooms.
Yeast are 8 urn and molds are 40 - 100
urn.
Mycology is the study of fungi.
4. ALGAE• eukaryotic, photosynthetic plants that
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range in size from a single cell to giant
kelp 30 m. in length.
One genus produces neurotoxins causing
shellfish poisoning.
Microbiologist are interested in the algae
classified in the kingdom Protista.
Extremely important in food chain in
oceans.
Phycology is the study of algae.'
5. VIRUSES
• -neither prokaryote or eukaryote.
• Viruses are obligate intracellular
parasites.
• This means that the virus depends on
the host'cell for reproduction and
growth.
• Viruses are non-cellular, infectious
agents composed of a nucleic acid
surrounded by a protein coat.
• Viruses are considered the link
between the living and the nonliving.
• Cause diseases such as herpes,
rabies, flu, hepatitis, polio, and
chickenpox.
• Only observable activity is
reproduction.
• Viruses are measured nanometers.
Smallpox largest ( 250nm) polio
smallest ( 20 nm)
• Virology is the study of viruses.
Bacteria Morphology: the size,
shape, structure and arrangement of
cells.
• SIZE - average one urn.
• Because of small size have high surface area to
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volume ratio. This explains the high rate of
growth and metabolism. Sphere has the smallest
surface area to volume ratio.
SHAPE - three basic shapes governed by cell wall.
coccus - spherical, may be oval, elongated, or
indented.
bacillus-rod
spiral-helically curved
a. vibrios-comma shaped
b. spirilia-rigid cell wall with flagella
c. spirochetes-flexible wall with no flagella
• diplococcus - cells divide in one plane and
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remain attached in pairs.
streptococcus - cells divide in one plane
and remain attached to form chains.
tetracoccus - cells divide in two planes and
form groups of 4 cells.
staphylococcus - cells divide in three
planes and produce grape like clusters of
bacteria.
sarcinae - cells divide in three planes in a
regular pattern producing cuboidal
arrangement of cells.
Occasionally bacterial cells may be star
shaped or square.
BACTERIAL SIRUCTURES
Structures External to Cell Wall
• 1. Glycocalyx-general term used for
substances that surround the cell.
• Viscous, gelatinous substance
composed of polysaccharide,
polypeptide, or both.
• A. Capsule-a glycocalyx that is organized and
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firmly attached to the cell wall. Forms in various
species of bacilli and cocci,
BUT NOT IN SPIRAL BACTERIA.
Functionsprovide protection against drying by binding
water molecules
blocks attachment by bacteriophages
may be antiphagocytic (enhibits engulfment of
pathogenic bacteria by white blood cells.
promotes attachment of bacteria to surfaces
5. if capsule has electrical charge may promote
stability of bacterial
suspension by preventing cells from settling
out.
• B. Slime layer - glycocalyx of looser
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consistency and less tightly bound to cell
wall.
Contains mass of tangled fibers of
polysaccharide called dextran.
Attaches bacteria to tissue. EX.
Alcaligenes viscolactis - ropy milk
Bacillus subtilis • ropy bread
Streptococcxis mutans - tooth decay
• 2. Flagella - Hairlike, helical
appendages composed of protein
that protrude through the cell wall
and are responsible for swimming
motility.
• They are much thinner and less
complex in structure than eukaryotic
flagella
Location of Flagella
• A. monotrichous - 1 flagellum at one
pole of cell.
• B. amphitrichous - 1 flagellum at
each pole of cell.
• C. lophotrichous - a tuff of flagella at
one pole.
• D. peritrichous - flagella
Composed of three parts:
• A. helical filament - usually several times
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as long as the cell. 20 nm.in diameter
B. short hook
C. Basal body-ring shaped bases (2 in
Gram negative and 1 in Gram positive
cells) associated with cell wall and cell
membrane.
Common in spiral and rod shaped bacteria
but Rare in cocci.
Taxis: movement toward or
away from a certain stimulus.
• Chemotaxis refers to movement
toward or away from a chemical.
• Phototaxis refers to movement
toward or away from light
• 3. Pili and fimbriae - hollow, non
helical, filamentous appendages that
are thinner, shorter, and more
numerous than flagella.
• Do not function in motility.
Composed of protein pilin.
• A. Fimbriae may be located all over
the bacteria and function in
attachment.
• B. Pili - one or two per cell and
function in the transfer of
DNA. Called sex pili.
• Fimbriae are found primarily on Gram
negative bacteria
• Endospores - a highly resistant,
metabolically dormant form which
under appropriate conditions can
germinate to form a new vegatative
cell. This is a survival mechanism for
the cell. Spores resistance due to:
• dehydration
• large amounts of dipicolinic acid
Endospore
• Spore formation is genetically determined.
• Spore formation is NOT a form of reproduction.
• Spore formation is found primarily in Gram
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positive organisms.
Spores can remain alive in boiling water for
hours, can survive
The genera Bacillus and Clostridium are the
best known spore formers.