anatomy of microorganism Flashcards
universal ancestor
Domain Eukarya
Domain Archae
Domain Bacteria
Domain Archae
E
C
N
K
Euryarchaeotes
Crenarchaeotes
Nanoarchaeotes
Korarchaeotes
Domain Bacteria
P
Cl
S
C
Gp
Proteobacteria
Chlamydias
Spirochetes
Cyanobacteria
Gram- Positive bacteria
any cells that defined a clearly nucleus and membrane bound organelles
Eukaryotic cells
an unicellular organism that does not contain nucleus, membrane or organelles.
Prokaryotic cells
can be found in animals, plants, fungi, and protist cells
eukaryotic cells
are bacteria and archae
prokaryotic cells
present in nucleus
eukaryotic cells
Absent in nucleus( nucleod region)
prokaryotic cells
large (10-100) in micrometer
eukaryotic cells
small (< 5 micometer)
prokaryotic cells
DNA replication
highly regulated with selective origins and sequences
eukaryotic cells
DNA replication
replicates entire genomes at once
prokaryoric cells
organism type
usually multicellular
eukaryotic cells
organism type
unicellular
prokaryotic cells
chromosomes
more than 1
eukaryotic cells
chomosomes:
one long single loop of DNA and plasmids
prokaryortic cells
ribosomes:
large
eukaryotic cells
ribosomes:
small
-prokaryotic cells
growth rate/ generation time of eukaryotic
slower
growth rate/ generation time of prokaryotic
faster
organelles
present
eukaryotic cells
organelles
absent
prokaryotic cells
common characteristics of eukaryotic and prokaryotic cells
ability to store hereditary information
plasma membrane
cytoplasm
ribosomes
cell division
flagella
chromosomes
Cell wall of eukaryotic cells
simple: present in plants and fungi
Cell wall of prokaryotic cells
complex: present in all prokaryotes
Binary fission
Prokaryotes
undergo mitosis
eukaryotes
cytoskeleton
eukaryotes
linear DNA with histones
eukaryotes
cicular DNA
prokaryotes
complex appendages
eukaryotes
simple appendages
prokaryotes
their name comes from
the Greek eu, “true” and karyon, “nut” or “kernel“.
Domain Eukaryota or eukarya
A typical eukaryotic cell is surrounded by a ______
and contains many different______with a variety of functions.
plasma membrane
structures and organelles
The major groups of EUKARYOTE
microorganisms
(fungi, protozoa, and algae),parasitic worms and mites, and all plants and animals up to
and including humans
Strengthen and give shape to the cell
Cell wall and pellicle (EC)
Photosynthesis—trapping light energy and formation of carbohydrate from CO2 and water
Chloroplasts (EC)
Cell movement
Cilia and flagella (EC)
Environment for other organelles, location of many metabolic processes
Cytoplasmic matrix (EC)
Transport of materials, protein and lipid synthesis
Endoplasmic reticulum (EC)
Packaging and secretion of materials for various purposes, lysosome information
Golgi apparatus (EC)
Intracellular digestion
Lysosomes (EC)
Cell structure and movements, form the cytoskeleton
MF
IF
MT
Microfilaments, intermediate
filaments, and microtubules (EC)
Energy production through use of the tricarboxylic acid
cycle, electron transport, oxidative phosphorylation, and
other pathways
Mitochondria (EC)`
Ribosomal RNA synthesis, ribosome construction
Nucleolus (EC)
Repository for genetic information, control centre for cell
Nucleus (EC)
Mechanical cell boundary, selectively permeable barrier with
transport systems, mediates cell-cell interactions and
adhesion to surfaces, secretion
Plasma membrane (EC)
Protein synthesis
Ribosomes (EC) (PC)
Temporary storage and transport, digestion (food vacuoles),
water balance (contractile vacuole)
Vacuole (EC)
is coined from two Greek
words pro, before, and karyon, nut or kernel.
Prokaryotes or Procaryotes
used to describe unicellular (single-celled) organisms that
lack true nucleus and membrane-bound cell organelles.
This means that the genetic material in _____is
not bound within a nucleus.
Prokaryotes or Procaryotes
divided into two domains,
Bacteria and Archaea.
Common prokaryotic cell types.
(a) cocci, or spherical
(b) bacilli, or rod-shaped
(c)spirilli, or spiral-shaped
archaebacteria
-methanospirillum hungatei
-methanobacterium thermoautotrophicum
-thermoacidophiles
-methanobacterium ruminantium
-methanospirillum bacteri
-methanogenium thermophilum
eubacteria
-Gleocapsa
-anabaena spiroides
-gram positive
-gram negative
Resistance to phagocytosis, adherence to surfaces
Capsules and slime layers (PC)
Gives bacteria shape and protection from lysis in dilute
solutions
Cell wall (PC)
Survival under harsh environmental conditions
Endospore (PC)
Attachment to surfaces, bacterial mating
Fimbriae and pili (PC)
Provides the power of motility or self-propulsion
Flagella (PC)
Buoyancy for floating in aquatic environments.
Gas vacuole (PC)
Storage of carbon, phosphate, and other substances
Inclusion bodies (PC)
Localization of genetic material (DNA)
Nucleoid (PC)
Contains hydrolytic enzymes and binding proteins for
nutrient processing and uptake’
Periplasmic space (PC)
Selectively permeable barrier, mechanical boundary of cell,
nutrient and waste transport, location of many metabolic
processes (respiration, photosynthesis), detection of
environmental cues for chemotaxis
Plasma membrane (PC)
- more standard
energy
production
EUBACTERIA
- less standard
energy
production
ARCHAEBACTERIA
is the biological conversion of one or more carbon-containing molecules
(usually carbon dioxide or methane) and nutrients into organic matter using
the oxidation of inorganic compounds
Chemosynthesis
is the biological conversion of one or more carbon-containing molecules
(usually carbon dioxide or methane) and nutrients into organic matter using
the oxidation of inorganic compounds
Chemosynthesis
Energy: Chemosynthesis*
Archaebacteria
- unicellular organisms without nuclei
- No organelles
- Have cell walls
- Lacks peptidoglycan
- DNA is more similar to eukaryotes, denotes lineage.
- Live in extreme environments
- No oxygen
- hot springs, deep ocean
Archaebacteria
*Protecting cell against ion & pH fluctuations, osmotic stress,
degrading enzymes or predacious bacteria.
helps in maintaining shape & envelope rigidity of the cell.
* it promotes cell adhesion to surfaces
* widely studied recently especially in connection with
nanotechnology due to their ability to self assemble protein
units without the aid of enzymes.
archaebacteria cell wall
- S-layer could be used technologies such as drug delivery
systems & novel detection systems for toxic chemicals.
Future Prospects: archaebacteria
Major Types of Archaebacteria Cell Wall
type 1,2,3,4,5
*The most common type of archaeal cell wall is an S layer composed of
either protein or glycoprotein.
* Thickness: 20-40nm thick
* S-layer cell walls are present in some Methanogens like Methanococcus,
Halophiles and Extreme Thermophiles like Sulpholobus and Pyrodictium
etc.
type 1 AB cellwall
- Additional layers of material are present outside the S-layer. In
Methanosprillum, there is a protein sheath external to the S-layer.
type 2 Ab cell wall
- In Methanosarcina, S-layer is covered by a chondroitin like material called as ________
type 3 AB cell wall
-methanochondroitin.
- In some Archae like Methanothermus and Methanopyrus, S-layer is
the outermost layer and is separated from the plasma membrane by
a peptidoglycan-like molecule called_________
type 4 AB cell wall
- psuedomurein.
differ from Peptidoglycan in having N-acetyltalosaminuronic acid instead of N-acetyl muramic acid, L-amino acids instead of D-amino acids that cross links and Beta (1->3) glycosidic linkage instead of Beta (1->4) glycosidic linkage.
Psuedomurein
- In this type, S layer is absent. Instead archeal cell wall is single
thick, homogenous layer resembling Gram positive bacteria. These
archaea often stain Gram positive. This type is present in
Methanobacterium, Halococcus etc.
type 5 AB cell wall
enable the cell to survive
and multiply
– essential structures
– “optional” structures
Prokaryotic Cell Structure
have important
consequences for human
health
Prokaryotic Cell Structure
important in identifying
bacteria
Prokaryotic Cell Structure
- Examination of a bacterial cell reveals
components of structures - Some external to cell wall
- Others internal to cell wall
Structure of a Bacterial Cell
(Bacterial Anatomy)
- It is a thin layer lining the inner surface of the cell wall.
- Semipermeable membrane controlling the flow of metabolites
- Chemically, consists of Lipoprotein and carbohydrates. Sterols are absent
Cell Membrane (bacterial cell)
- structure the same with other biological membranes
- about __nm thick
*______% phospholipid + _____ % protein - fluid-mosaic model
- no sterols (Archaea and Bacteria), with ________ (Bacteria)
Cell Membrane (Bacterial cell)
-8
-40%
-60%
-hopanoids
- members of Bacteria and Archaea have the same general
structure of their cytoplasmic membranes, but the lipid
compositions are distinctly different
Cell Membrane (bacterial cell)
– the glycerol used to make archaeal phospholipids is a stereoisomer of the
glycerol used to build bacterial and eukaryotic membranes
chirality of glycerol
Differences between bacterial and archaeal phospholipids:
CG
SC
L
BSC
- chirality of glycerol
- linkage
- side chains
- branching of side chains
linkage
ester- D-glycerol
vs.
ether linkage- L-glycerol
branched tail
ether linkage
unbranched tails
ester linkage
side chains
(fatty acids -unbranched
vs.
isoprenoid chains- branched)
– different physical structures; can form carbon rings
branching of side chains
in some species, the opposing phospholipid
tails are joined into a single tail, forming a monolayer
stabilize the membrane at high temperatures
lipid bilayer
bacteria and eukaryotes
lipid monolayer
some archae
embedded in or loosely attached to the cell membrane
Cell Membrane Proteins
Cell Membrane Proteins
C
C
R
R
E
-channel
-carrier
-recognition
- receptor
-enzymatic
Prokaryotic Cell membrane
Functions
- permeability barrier
- regulate movement of materials into and out of cell
- contains proteins that transport nutrients into the cells
and eliminate waste materials - synthesizes cell wall components
- assist with DNA replication (anchors DNA)
- secretes proteins
- carries on cell respiration (ATP synthesis)
- contains bases of flagella
- proteins respond to chemical substances in the
environment
– small molecules like water, oxygen, carbon dioxide, and
hydrophobic molecules can move freely (simple diffusion)
– large or charged molecules like proteins, sugars, and ions
can not (specific membrane proteins)
- selectively permeable
- semifluid substance inside the cell membrane
- 4/5 water + 1/5 dissolved substances (enzymes, proteins,
carbohydrates, lipids, salts, vitamins and various inorganic
ions) - where chemical reactions take place
Cytoplasm
- Colloidal system of variety of organic
and inorganic solutes in viscous watery
solution - No ER and Mitochondria
- Contains mesosomes, inclusions, and
vacuoles
Cytoplasm
- Vesicular, convoluted invaginations of the
plasma membrane - Prominent in GM+ bacteria
- Principal sites of Respiratory enzymes
- Analogous to mitochondria in Eukaryotes
Mesosomes
- Formed by extensions of the cell
membrane into the cell. - Help in respiration and secretion
processes. - Help to increase the surface area
of cell membrane as a result
increases the enzymatic content
of the cell.
MESOSOMES
- chromosome region
- gel-like region containing the chromosomes and
plasmids
nucleod
can be seen as an invagination of the cell membrane. it is made up of similar structural components.
mesosomes
- single, circular, double-stranded
DNA molecule that contains all
genetic information required by a
cell - 1 mm long
- 10% of cell’s total volume
– supercoiled chromosomal DNA
chromosomes
complexed with proteins
resembling histone proteins
*Archaea chromosome
width of Dna Fiber
250 nm
coil length
300 nm
histone size
11nm
coiles histone diameter
30 nm
dna double helix diameter
2 nm
chromosome size
1400 nm`
supercoil length
700 nm
- accessory genetic information
- circular, supercoiled, double stranded DNA molecules
- 0.1 – 10% of chromosome size
- contains hundreds of genes (5-100 genes)
Plasmids
- can be of many types per cell
- not required but may provide bacteria
with genetic advantage - may contain genes for antibiotic resistance
(R), disease production - can be transferred and spread to other
bacterial cells - replicate independently from chromosome
plasmids
- consist of ribonucleic acid (rRNA) and
protein (ribosomal protein) - <20,000
- nearly spherical, stain densely, and contain a
large and small subunits
ribosomes
2.56x10^6 D
70s (ribosomes)
0.93x10^6 D
30s (subunits)
1.59x10^6 D
50s (subunits)
16s RNA (30s)
1542 nucleotides
23s RNA(50s)
2904 nucleotides
30s proteins
21 proteins
50s proteins
31 proteins
- sites for protein synthesis
– protein –_____ % of bacterial cell dry weight
– _____ % of cell energy is for protein synthesis - the faster the cell is growing, the faster proteins are produced, the greater the number of ribosomes
- site for antibiotic action_______
ribosomes
-50%
-90%
-(streptomycin and
tetracycline)
prokaryotic ribosome
70s
70s RNAs
5s RNA
23s RNA
16s RNA
eukaryotic ribosome
80s
80s subunits
60s
40s
80s RNAs
5s RNA
5.8s RNA
28S RNA
18s RNA
– Chromatophores/ chlorosomes – contain the
pigments used to capture light energy for
synthesis of sugars
phototosynthetic bacteria and cyanobacteria
– convert nitrogen compounds into plant-useable
form
– house the enzymes used in deriving energy from
oxidation of nitrogen compounds
- nitrifying bacteria
- phototosynthetic bacteria and cyanobacteria
- nitrifying bacteria
Internal Membrane Systems
- variety of small bodies within
the cytoplasm - storage of materials that are
later use as source of nutrients - reservoir of structural building
blocks - granules; vesicles
Inclusion Bodies
– intracellular small storage bodies
– vary in size, number, and content
– bacterial cell can use them when environmental
sources are depleted
– i.e. glycogen, poly b-hydroxybutyrate, gas vesicles
for floating, sulfur and phosphate granules
(metachromatic granules), particles of iron oxide
Granules and vesicles
accumulations of high molecular weight polymers
synthesized from a nutrient in excess
Storage Granules
Storage Granules contain specific substances densely compacted that do not dissolve in
cytoplasm
Fly
Vol
Str fr ele sf
Mag
– glycogen
– volutin granules/polyphosphate granules
(metachromatic granules)
– others: storage for elemental sulfur, magnetosomes
stored glucose polymer; carbon and energy
source
glycogen
stored phosphate
volutin granules/polyphosphate granules
(metachromatic granules)
- small, rigid protein-bound compartments that provide buoyancy to the cell
- 300-1000 nm x 45-120 nm
- aquatic, photosynthetic bacteria; cyanobacteria
Gas Vesicles (vacuoles)
- Maintaining the cell’s characteristic shape-
- Countering the effects of osmotic pressure
- Important role in cell division
- Providing attachment sites for bacteriophages
- Providing a rigid platform for surface appendages
- Be the sites of major antigenic determinants of the cell surface。
- Resistance to Antibiotics
function of cell wall
the rigid wall
compensates for the flexibility of the phospholipid membrane and
keeps the cell from assuming a spherical shape
Maintaining the cell’s characteristic shape
(type of virus that
infects bacteria. It literally means “bacteria eater,” because
bacteriophages destroy their host cells)
bacteriophages
sphere, 1μm
cocci
rods , 0.5-1 μm in width -3 μm in
length
Bacilli:
curved forms, 1~3 μm in length and 0.3-0.6
μm in width
Spiral bacteria
spirillum/ spirochetes
cocci in pairs
diplococci
coffee- bean shape in pairs cocci
Neisseriae
cocci in packets of 4
Tetrads
cocci in packets of 8,16,32 cells
Sarcinae
cocci in chains
streptococci
large cocci in irregular cluster
Micrococci and Staphylococci
small rod coccus
coccobacilli
long thin rod shape
mycobacteria
palisades arrangement
Corynebacteria
spore like bacteria
spore-forming rods
mold-like, filamentous bacteia
streptomycetes
curved rods
Vibrios
small curved length with hairs end tail
spirilla
long curved bacteria
spirochetes
protects cell from mechanical damage
(rigidity)
helps cell withstand pressure and prevents it from osmotic rupture or lysis
Essential for bacterial viability
no net movement of water
isotonic solution
water moves into the cell and may cause the cell to burst if the wall is weak or damaged (osmotic lysis)
Hypotonic solution
water moves out of the cell causing cytoplasm to shrink ( plasmolysis)
Hypertonic solution
provides structural integrity to the
cell.
Bacterial cell wall
The bacterial cell wall differs from that of all other
organisms by the presence of
Peptidoglycan.
Peptidoglycan (Mucopeptide) is composed of
alternating chains of
- N -Acetyl Glucosamine and N-Acetyl Muramic
Acid, which is cross linked by Peptide chains
is responsible
for the rigidity of the
bacterial cell wall and for
the determination of cell
shape
Peptidoglycan
Based on the composition of
cell wall & Staining
bacteria are classified into
“Gram positive” and “Gram Negative”
- peptide + glycan
- murein
- macromolecule found only in bacteria
- molecules of N-acetylglucosamine (NAG) alternate with
molecules of N-acetylmuramic acid (NAM) crosslinked by
peptides - structure varies in Gram-positive and Gram-negative bacteria
Peptidoglycan
- NAG and NAM subunits are covalently joined to
one another to form a glycan chain - high molecular weight linear chain
- serves as backbone of the peptidoglycan molecule
B-1-4-glycosidic bond
polysaccharide chains ( the glycan portion)
NAG
pept protion
peptide cross link
tetrapeptide
L-ala
D-glu
MDA
D-ala
L-alanine
D-glutamic acid
Meso Diaminopimelic acid
D-alanine
Pentapeptide
L-ala
D-glu
MDA
Two D-ala
L-Alanine
D- glutamic acid
Meso Diaminopimelic acid
2D- Alanine
different bacterial species, different amino
acid composition
Tetrapeptide
- The______is characterized
by the presence of a very thick peptidoglycan
layer (≈30 layers) - 20-80 nm thick
- Cell wall contains 90% Peptidoglycan and
10%Teichoic acid - fully permeable to many substances (sugars, amino acids, ions)
- gram-positive cell wall
- anionic glycopolymers
- These polymers play crucial roles in cell shape determination, regulation of cell division, and other fundamental aspects of Gram-
positive bacterial physiology.
gram-positive cell wall
Interwoven in the cell wall of Gram-positive are
Teichoic acids and lipoteichoic acids (covalently bonded to NAM)
composed of polymers of glycerol,
phosphates, and the sugar alcohol- ribitol.
Teichoic acids
-contains a thin
peptidoglycan layer adjacent to the
cytoplasmic membrane
-also contains an additional outer membrane composed by phospholipids and lipopolysaccharide (LPS) which face into the external environment and periplasmic space
Gram Negative Cell Wall
- a bilayer membrane
- composed of phospholipids,
polysaccharides, and proteins - contains lipopolysaccharide
(LPS) - attached to the peptidoglycan by
almost continuous layer of
lipoproteins
Outer Membrane
embedded in the
outer membrane and
covalently bonded to the
peptidoglycan
liporoteins
“coarse sieve”
* barrier to passage of most molecules
* excludes compounds that are damaging to cell
* has porins
* secretion systems
Outer Membrane
– specialized channel-forming proteins
– channels for low molecular weight substances
porins
– translocate proteins produced to the
outside of outer membrane
secetion system
The LPS (in outer membrane) present on the Gram
negative cell wall consists of 3 regions:
- Polysaccharide determining O antigen
- Core Polysaccharide
- Glycolipid portion /Lipid A
causes a form of Septic shock for which there is no
direct treatment.
LPS or endotoxin
Lipopolysaccharide (LPS) PARTS
- Lipid A – responsible for toxic properties of G-
bacteria (endotoxin) - O-specific polysaccharide (O-antigen)
– anchors the LPS in the bilayer
– composition recognizable by body as
presence of invading bacteria
– small amounts may elicit defense system
response enough to effectively eliminate the
pathogen
Lipid A – responsible for toxic properties of G-
bacteria (endotoxin)
– side chain portion of LPS directed away from
the membrane
– chains of sugar molecules with varying
composition and lengths
– used to identify certain species or strains
– i.e. E. coli O157:H7
O-specific polysaccharide (O-antigen)
- most observed among G- bacteria, rarely in G+ bacteria
- gel-like fluid (periplasm) and protein-filled (secreted proteins)
- very active area of cell metabolism (i.e. nutrient degradation and transport)
- contains digestive enzymes and transport proteins
Periplasmic Space
(destroy potentially harmful
substances
digestive enzymes
(transport metabolites into the
bacterial cytoplasm)
transport proteins
In Streptococcus pneumoniae (Gram positive) Teichoic acid bears the antigenic determinants called
“Forssman antigen”
constitute for the major surface antigens.
Teichoic acids
one of the most important sites for attack by antibiotics
- penicillin
- compounds that interfere with the synthesis of
peptidoglycan or alters its structural integrity
compounds that interfere with the synthesis of
peptidoglycan or alters its structural integrity
– penicillin
– enzyme lysozyme
– interfere with peptidoglycan synthesis
– binds to proteins involved in cell wall synthesis
– prevents cross-linking of glycan chains
– more effective against G+ bacteria
– modified to create derivatives that can pass through
porin channels
penicillin
– found in many body fluids
– breaks bond between the NAM and NAG molecules
lysozyme
Targeting the Peptidoglycan
lysozyme
thickness of peptidoglycan in gram-positive and gram-negative
G-P _ 16-80 nm
G-N_ 2nm
retain dye color and dark
gram-positive
can be decolorized
Gram- Negative
LONG PPT
Lipopolysaccharide
Outer membrane
Negative
Gram
Positive
Peptidoglycan (thick)
Teichoic acid
The Gram staining method, named
after the Danish bacteriologist who
originally devised it in 1882
(published 1884)
Hans Christian
Gram
is one of the most important
staining techniques in microbiology.
Hans Christian
Gram
- most frequently used differential stain
- devised by Hans Christian Gram in 1884
Gram Stain
primary stain
crystal violet
mordant
iodine
95% ethanol
decolorizer
counterstain
safranin –
all bacteria will be stain
bluish or bluish purple
stain will be fixed due to formation of a complex of
crystal violet and KI (mordant)
destaining will be done by
water and alcohol
- Mycoplasma species
- variable shape
- have sterols in their cell membranes (stability)
Cell Wall-Less Bacteria
cell wall appendages
Glycocalyx
S-layer
Flagella
Fimbriae
Pilli
capsule
slime layer
-is a general term for any network of
polysaccharide (and small proteins) lying outside the
cell
Glycocalyx
less discrete structure or matrix which
embeds the cell ; diffuse and irregular
slime layer
discrete detectable layer of
polysaccharides deposited outside the cell wall; distinct and gelatinous (thicker and more rigid)
capsule (true capsule)
consists largely of water an content of solids 2%
capsule and slime layer
in most species, the solid material is
in some
complex polysaccharide
polypeptide or protein
There are two types of Glycocalyx
capsule
slime layer
When glycocalyx is tightly bound to the cell wall of
bacteria, it is referred to as _____. It is gelatinous in nature and cannot be easily stained and removed from the bacterial cell wall
CAPSULE
The glycocalyx is called “_____ if it is loosely bound to the cell wall of bacteria. ____is irregular and can easily be removed from the bacterial cell wall.
SLIME LAYER
Functions of Capsules
- Antiphagocytic,thus contribute “Virulence”.
- protects against “Lysozyme”
- Promote attachment of bacteria to surface
(e.g. Streptococcus mutans) - Permits bacteria to adhere to Medical
Implants & Catheters. - helps trap nutrients near the cell
- protect soil bacteria from desiccation
- reserves of carbohydrates
- mediate adherence of cells to surfaces
- protect bacterial cells from engulfment
- capsules protect soil bacteria from desiccation
- when overproduced may become reserves of
carbohydrate - helps trap nutrients near the cell
- bind cells together and float themselves as colonial
masses in their environments
Functions of Glycocalyx
Disease:
Protection:
Adherence to surfaces:
Avoidance of desication:
In cell-cell recognition:
Functions of Glycocalyx
Disease:
Protection:
Adherence to surfaces:
Avoidance of desiccation:
In cell-cell recognition:
It is a virulence factor in most bacteria, and it contributes to their ability to cause diseases in their host.
disease
Glycocalyx protects bacteria from antibiotics, chemicals and against the lytic and phagocytic activities of host’s white blood cells.
protection
The sticky nature of the glycocalyx enables
bacteria to attach themselves firmly to the surface of their host. Streptococcus mutans, the causal agent of tooth decay adheres to the surface of decaying teeth with the help of glycocalyx.
Adherence to surfaces
Glycocalyx (especially capsule) contains
water as its constituent. This help to prevent dryness of the bacterial cell.
Avoidance of desiccation
The glycocalyx carries receptors on their
surface that allows them to bind to other cells of close species.
In cell-cell recognition
The slime layer of Gram+ ______allows it to accumulate on tooth enamel and one of the causes of cavities.
Streptococcus
- some enables bacteria to adhere to specific surfaces and grow as a BIOFILM
- prevents host defense mechanism from destroying the
bacteria (i.e. Streptococcus pneumoniae) - only some bacteria and some members of a species are
capable of producing capsule (i.e. Bacillus anthracis)
Capsule and Slime Layer
polysaccharide-encased mass of bacteria coating a surface
(i.e. Streptococcus mutans and dental plaque)
Biofilm
-Forms a biofilm of 300-500
cells in thickness (10μm)
-Cleaves sucrose to glucose
and fructose
-Production of dextran or lactic
acid within the biofilm
Dental plaque by
Streptococcus mutans
- is a sharply defined, organized structure
(e.g.: Pneumococcus)
Colorless capsule surrounding the
bacterial cell - Most bacterial capsules
are composed of
Polysaccharides
e.g.: Klebsiella pneumoniae - A few capsules are
Polypeptides
e.g.: Bacillus anthracis
capsule
unencapsulated S. pneumoniae are harmless
Streptococcus pneumoniae
-Some bacterial species are
mobile and possess
locomotory organelles
-consist of
a number of proteins
including flagellin
Flagella
The diameter of a flagellum
is thin
20 nm, and long with
some having a length 10
times the diameter of cell.
*helical; corkscrew-shaped
*10-20 μm long and 10-20 nm thick and come in a number of distinct arrangements
* responsible for bacterial motility/locomotion (pushes
bacterium through liquid)
* spins like a propeller (rotates both clockwise and
counterclockwise)
* uses proton motive force as energy (1000 protons per
movement)
* Rotation: >1500 rpm; Rate: 10 body
lengths/second
flagella
- Unbranched, long, filaments, made up of protein “Flagellin”
- Organs of locomotion
- Found in all motile bacteria except Spirochetes
- Flagella are highly antigenic,
- Termed as the ‘H’ Antigen.
- Some of the immune responses are directed against these
proteins.
flagella
- may be important in the ability of an
organism to cause disease (i.e. Helicobacter
pylori have powerful multiple flagella)
Flagella
Structure and Arrangement
of Flagella
* has three basic parts
– filament (flagellin)
– basal body (motor)
– hook
twisted but with hollow core
filament
anchored in cell membrane and cell wall;
rings and rod
basal body
wide region at the base
of flagella; connects the two
parts
hook
bacteria that have the powerful multiple flagella
helicobacter pylori
type of flagellar arrangement
M L A P A
polar/monotrichous
Lophotrichous
Amphitrichous
Peritrichous
Amphilophotrichous
Single flagellum at one pole
polar/Monotrichous
Tuft of flagela at one pole
- spirillum
Lophotrichous
flagella at both poles
-Alkaligenes faecalis
Amphitrichous
Flagella all over
- E.Coli
-Salmonella
-Bacillus spp.
peritrichous
tuft of flagella at both ends
Amphilophotrichous
Kinds of Motility:
DM
TM
CSM
SM
SeM
- Darting motility :
V.cholerae - Tumbling motility:
L.monocyctogenes - Cork &screw motility:
T.pallidum - Stately motile :
Clostridium spp. - Serpentine motility:
Salmonella
(Except
S.gallonarum pullorum)
bacterial behavior in seeking out favorable
environments and avoiding harmful ones
Taxis
types of Taxis
- chemotaxis
- aerotaxis
- phototaxis
- magnetotaxis
– sense chemicals and move toward regions that contain more nutrients (attractant) and away from regions with toxic materials (repellant)
chemotaxis
– swim to regions that contain favorable concentrations of dissolved oxygen
aerotaxis
– movement to regions of optimal light intensity and quality
phototaxis
– response to Earth’s magnetic field
magnetotaxis
_________ of a monotrichous polar flagellum pushes the cell forward with the flagellum trailing behind, much like a corkscrew moving inside cork.
Counterclockwise rotation
Flagella are _______ and bundle and rotate together only when rotating counterclockwise.
Left-handed helices
When some of the rotors reverse direction, the flagella unwind and the
cell starts______________________________________
“tumbling”.
Even if all flagella would rotate clockwise, they likely _____
will not form a bundle.
may happen occasionally,
leading to the cell seemingly thrashing
about in place, resulting in the reorientation of the cell.
Tumbling
Detection of motility and presence of Flagella:
- Direct observation by hanging drop method
- Dark field microscopy
- Motility media (such as Sulfide Indole Motility Media)
- Flagellar staining
- Electron microscopy
- Immunological detection of “H” antigen
- tiny, hollow projections not involved in movement
- shorter, thinner, and straighter than flagella
pili
– helical structure around a central hollow core
pili protein
- two types of pili
– attachment pili (fimbriae)
* with adhesins
– conjugation pili/ sex pili/ F pili
* longer than attachment pili
* DNA transfer from one cell to another
- Hair like surface appendages
- 0.5-10 nm thick
- Shorter and thinner than flagella
- Formed of protein subunits – Pilin
Fimbriae
Special type of Fimbriae
Sex Pili
Clumping of RBCs
(Escherichia, Klebsiella)
Hemagglutination
- helps bacteria to adhere to surfaces (interface), to
other bacteria, or to other cells
– contains adhesin proteins - contributes to the pathogenicity by enhancing
colonization and attachment on cell surfaces (i.e.
Escherichia coli and diarrhea) - some species produce different types of fimbriae i.e. Neiserria gonorrheae on urogenital tract
Fimbriae
- similar in structure to fimbriae but are generally longer
- one or few per cell
- functions in gene transfer
- may serve as specific receptors for certain types ofvirus particles
- some are involved in attachment to human tissues
Conjugation Pilus
- resting (dormant) stages of vegetative cells of some bacterial species (Bacillus and Clostridium)
- very resistant to heat and harmful agents (drying, cold, radiation, acids, bases, chemical disinfectants)
- produced through sporulation
- spores may remain dormant for 100 years
Endospores (SPORES)
are protection for bacterial genome
not a form of production , only one new cell germinates from each spore
can be found in bacillus and clostridium
Endospore
- Dormant cell
- Resistant to adverse
conditions - high temperatures
- organic solvents
- Produced when starved
- Contain calcium
dipicolinate
DPA, Dipicolinic acid
Endospores
(spores)
⚫ Identification of
Bacteria
⚫ Pathogenesis
⚫ Resistance
Endospore
endospore contains
core, cortex, spore coat, exosporium (some)
– thin, delicate covering made of protein
exposporium
– composed of spore-specific proteins
– “sieve”
– excludes substances such as lysozyme
spore coat
– loosely cross-linked peptidoglyan
– maintains core in a dehydrated state
– protects core from effects of heat
cortex
– has small, acid-soluble proteins that bind DNA
– contains the core wall, cell membrane, cytoplasm, nucleoid, etc.
– rich in _____ and calcium ions; partially dehydrated (10-30% water)
-contains core-specific proteins (small acid-soluble spore proteins)
core (spore protoplast)
‘dipicolinic acid’
contains core-specific proteins (small acid-soluble spore proteins)
- bind tightly to core DNA and protect it from UV radiation, dessication, dry heat
- carbon and energy source during germination
metabolically inactive
Core
Location important in classification of endospore
– central, subterminal, terminal
– Used for quality control of heat
sterilization equipment
Bacillus stearothermophilus spores
Used in biological warfare
Bacillus anthracis spores
position of spores
nonbulging
SC
OC
OS
bulging
OS
OT
ST
NONBULGING
spherical central
Oval central
Oval Subterminal
BULGING
Oval Subterminal
Oval terminal
Spherical terminal
- complex, yet highly ordered sequence of changes that
initiates when cells are grown in low amounts of carbon or
nitrogen - ≈8 hours
sporulation
triggered by brief exposure to heat or certain chemicals
Germination
s differential staining technique is used to distinguish between the vegetative cells and the endospore.
the endospore staining
the procedure of staining was designed by on 1930’s also kknown as Wirtz-Conklin method
Alice B. Schaeffer and Mc Donald Fulton
contains genetic material
nucleus
this is the outer membrane
pellicle
many protoa can ingest small food particle
food particle
many protoa can ingest small food particle
food particle
this structure makes and transfer poteins
Endoplasmic reticulum
produce energy needed by the cell to function
Mitochondria
contains dissolve food and chemicals for addition waste products
cytoplasm
-produce energy needed by the cell to function
-envelopes the cell; fxns
as the locomotor apparatus for the procurement & ingestion of food, in respiration, discharge of metabolic wastes & protection of the org.
Ectoplasm
-and an inner, more watery grainy
mass containing structures called organelles.
-food synthesis takes place; & food is stored in the
form of glycogen or protein called
chromatoidal bodies.
endoplasm
- locomotory organelles arising from the ectoplasm may vary from:
a) Cilia
b) Pseudopodia
c) Flagella
in Ciliates; numerous short threads distributed over the surface of the body.
cilia
false feet; in Amoebae
(crawling movement)
Pseudopodia
in flagellates; hair-like projections
Flagella
Absorb liquid nutrients from the medium or ingest bacteria & cells at any site of the body surface.
Protozoan
Others have specialized cell mouth.
-located in anterior end of
the body.
CYTOSTOME
- Ciliates have in addition a cell anus at the posterior end of the body & through which particulate food wastes are discharged.
CYTOPYGE
-The typical life stages of protozoans:
Cyst
Trophozoite
The small productive nucleus of ciliate protozoa
smaller nucleus
less amount of DNA
responsible for reproduction for macronucleus
diploid
germline genome
silent
Micronucleus
large non-reproductive nucleus of ciliate protozoa
large nucleus
higher amount of DNA
responsible of normal activity and functioning oforganism
polyploid
somatic genome
active
macronucleus
are vegetative or feeding
forms
Trophozoites
A more or less central body in the vesicular nucleus of certain protozoa (for example, trypanosomes, parasitic
amebae), with the chromatin.
endosome/karyosome
-Usually the infective stage
- highly resistant
Cysts – non-motile
move by the help of flagella
the movement is whip like
flagellates
examples of flagellates
trypnosoma, leishmenia (blod pathogen)
giardia (INTESTINAL PARASITE)
Trichomonas ( reproductive tract pathogen)
Characteristic features of the stained trophozoite include:
1) two nuclei (Nu) with central karyosomes (k),
2) fibrils running the length of the parasite –axonemes (Ax), and
3) Median Bodies (MB)/ Parabasal bodies
are not known, but most believe they are somehow involved with the adhesive disk and its formation.
median bodies
found in south and central america,
kidney-shaped macronucleus .reproduction by binary fission.
Balintidium Coli
found in south and central america,
kidney-shaped macronucleus .reproduction by binary fission.
Balintidium Coli
an be single celled or very complex multicellular organisms.
They are found in just about any habitat but most live on the land, mainly in soil or on plant material
rather than in sea or fresh water.
Fungi
Fungi are subdivided on the basis of their life cycles, the presence or structure of their fruiting body and the arrangement of and type of spores __________they produce.
(reproductive or distributional cells)
The three major groups of fungi are:
- multicellular filamentous molds
- macroscopic filamentous fungi that form large fruiting bodies. Sometimes the group is referred to as ‘mushrooms’, but the mushroom is just the part of the fungus we see above ground
which is also known as the fruiting body. - single celled microscopic yeasts
structure that help fungi absorb and digest food
Hyphae
mycelium
body of typical fungus , consisting many tiny tubes
Hyphae
Hyphae tangled into a thick mass
Mycelium
is also known as Penicillium notatum,
the first Penicillium fungi
used for the isolation of penicillin antibiotics, which is used for the treatment of Gram-positive
bacteria. It is also used in the production of other β-lactam antibiotics.
Penicillium chrysogenum
Unicellular Fungi
eukaryotic
facultative anaerobes
capable of making colonies on culture media
occur worldwide
over 1,500 species described
yeast
protective shell of virus
capsid
made of many identical protein subunits
protect the genetic material
symmetrically oraganized
50% weight
virus
a lipid -containing membrane that surrounds some virus particles
outside capsid
required for viral maturation
Envelope
helical-
polyhedral-
spherical-
complex-
tobacco mosaic model
adenovirus
influenza
bacteriophage
