Transcript No Slide Title

THE MICROBIAL WORLD:
MONERA: BACTERIA & ARCHAEOBACTERIA
PROTISTA: UNICELLULAR OR COLONIAL
EUCARYOTES THAT LACK TRUE TISSUE.
FUNGI: EUKARYOTIC ORGANISMS WITH ABSORPTIVE
NUTRITION & OFTEN MULTI-CELLULAR.
ANIMALIA & PLANTAE ARE NOT STUDIED BY THE
MICROBIOLOGIST.
VIRUSES: ACELLULAR/ NON-LIVING
SIZE, SHAPE & ARRANGEMENT OF PROCARYOTIC CELL
BACTERIA VARY IN THEIR SIZE FROM:
MYCOPLASMA (LACK CELL WALLS AND ARE THE
SMALLEST ORGANISMS CAPABLE OF INDEPENDENT
REPRODUCTION) TO THOSE APPROX. THE SIZE OF THE
LARGEST VIRUS (POX VIRUS).
SIZE, SHAPE & ARRANGEMENT OF PROCARYOTIC CELLS
BACTERIA (PROCARYOTES) COME IN A VARIETY OF SHAPE:
SPHERES (COCCI),
RODS (BACILLI),
CURVED RODS (VIBRIOS),
RIGID HELICES (SPIRILLA),
FLEXIBLE HELICES (SPIROCHETES),
LACKING A SPECIFIC CHARACTERISTIC FORM
VARIABLE SHAPE (PLEOMORPHIC, E.G., CORYNEBACTERIUM).
Bacillus
anthrax
Diplococcus
S. pneumoniae
staphylococcus
Bacillus w/spore
Tetanus bacillus
Diplococcus
gonorrhea
Vibrio, e.g.,
cholera
Club-shaped bacillus
diphtheria
Streptococcus
Spirilla, Rigid + flagella
Streptobacillus
Sarcinae/packet of 8
Cube-like
Spirocheted
Rigid/ no
flagella
SIZE, SHAPE & ARRANGEMENT OF PROCARYOTIC CELL
ARRANGEMENT:
BY REMAINING ATTACHED AFTER REPRODUCTION BACTERIA MAY
HAVE CHARACTERISTIC ARRANGEMENTS:
CHAINS (E.G., STREPTOCOCCUS);
CLUSTERS (E.G., STAPHYLOCOCCUS);
SQUARE PLANAR CONFIGURATION (TETRADS);
CUBIC, PACKAGES OF EIGHT CELLS, CONFIGURATION (SARCINAE).
PROCARYOTIC CELL ORGANIZATION & STRUCTURE
PROCARYOTIC CELL ORGANIZATION & STRUCTURE
TO OBSERVE BACTERIA, THEY MUST BE STAINED
STAINING & FIXATION PRESERVE FINE STRUCTURE OF
ORGANISMS.
FIXATIES INCLUDE HEAT OR CHEMICALS (ETHANOL,
GLUTERALDEHYDE, MERCURIC ACIDS)
FIXATIVES BIND TO MACROMOLECULES TO RENDER
THEM INSOLUBLE, INACTIVE & IMMOBILE.
STAINS
ACIDIC: HAVE IONIZING GROUPS (COOH) NEGATIVE
CHARGES; BIND TO POSITIVELY CHARGED CELL
STRUCTURES.
BASIC: HAVE POSITIVE CHARGES; BIND TO NEGATIVELY
PROCARYOTIC CELL ORGANIZATION & STRUCTURE
OBSERVATION OF BACTERIA REQUIRE SEVERAL STAINING
TECHNIQUES :
SIMPLE STAINING TECHNIQUES
SINGLE DYE TO ENHANCE THE CONTRAST OF THE SPECIMEN AGAINST THE
BACKGROUND.
DIFFERENTIAL STAINING
DIVIDES BACTERIA INTO DIFFERENT GROUPS BASED ON STAINING
PROPERTIES, e.g.,
GRAM STAINING
ACID FAST STAINING
SPECIAL STAINING TECHNIQUES
STAINING FOR SPECIFIC STRUCTURES. STAINS HAVE AFFINITY FOR CELL STRUCTURES
THEY HIGHLIGHT STRUCTURES AS STAINED COMPONENTS (POSITIVE STAINS)
ENDOSPORE STAINING
GRANULE STAINING
VS.
NEGATIVE STAINING - CELLS ARE LIGHT AGAINST A DARK BACK- GROUND
(E.G., STAIN WITH INDIA INK) - CAPSULE STAINING FLAGELLA STAINING
PROCARYOTIC CELL ORGANIZATION & STRUCTURE
PROCARYOTIC CELL ORGANIZATION & STRUCTURE
NEGATIVE STAINING TO OBSERVE CAPSULE
PROCARYOTIC CELL ORGANIZATION & STRUCTURE
PROCARYOTIC CELL ORGANIZATION & STRUCTURE
PROCARYOTIC CELL ORGANIZATION & STRUCTURE
PROCARYOTIC CELL ORGANIZATION & STRUCTURE
THE CYTOPLASMIC MEMBRANE IS MADE UP OF
AMPHIPATHIC LIPIDS IN A BILAYER AND IS SIMILAR TO
THAT OF THE EUCARYOTIC CELL. IT IS:
A SELECTIVELY PERMEABLE MEMBRANE
LOCATION OF METABOLIC ENZYMES & TRANSPORT
PROTEINS
SITE OF RESPIRATION
LIPID SYNTHESIS AND PHOTOSYNTHESIS
PROTEINS THAT ALLOW CELLS TO DETECT AND RESPOND
TO CHEMICALS RESIDE IN THE MEMBRANE
PROCARYOTIC CELL ORGANIZATION & STRUCTURE
CELL ENVELOPE = OUTER COVERING OF PROCARYOTES &
MADE UP OF PLASMA MEMBRANE + CELL WALL + OUTER
MEMBRANES (GRAM NEGATIVES)
PLASMA MEMBRANE
- SELECTIVELY PERMEABLE BARRIER
- PROVIDES STRUCTURAL INTEGRITY TO BACTERIA LACKING CELL
WALL (E.G., MYCOPLASMA)
- SIMILAR IN COMPOSITION TO EUCARYOTIC MEMBRANE
PROCARYOTIC CELL ORGANIZATION & STRUCTURE
AMPHIPATHIC MOL: HYDROPHILIC POLAR GROUP + HYDROPHOBIC NON-POLAR CHAIN
PROCARYOTIC CELL ORGANIZATION & STRUCTURE
CELL WALL MAINTAINS CELL SHAPE AND CONFORMATION
- RIGID, COMPLEX INFLEXIBLE LYER EXTERNAL TO CELL MEMBRANE
- ENABLES CELLS TO SURVIVE IN HYPOTONIC ENVIRONMENTS
- CELLS LACKING CELL WALL (MYCOPLASMA) COMPENSATE WITH STEROL
CONTAINING PLASMA MEMBRANES
- CELL WALLS ARE NOT UNIQUE TO BACTERIA (PLANTS = CELLULOSE;
FUNGi=CHITIN). BACTERI CELL WALL MADE UP OF POLYSACCHARIDE
CALLED PEPTIDOGLYCAN OR MUREIN
- ONE TO SEVERAL LAYERS THICK
- MADE UP OF REPEATING UNITS OF TWO CARBOHYDRATE DERIVATIVES:
N-ACETYLGLUCOSAMINE (NAG)
N-ACETYLMURAMIC ACID (NAM) - FOUND NOWHER ELSE IN NATURE
PROCARYOTIC CELL ORGANIZATION & STRUCTURE
PROCARYOTIC CELL ORGANIZATION & STRUCTURE
PROCARYOTIC CELL ORGANIZATION & STRUCTURE
B(1,4)
FOUR AMINO ACIDS MAKE UP WHAT IS CALLED A TETRAPEPTIDE,
ATTACHED TO THE NAM.
MOST GRAM POSITIVES COCCI HAVE SIMILAR TETRAPEPTIDE EXCEPT
DAP IS REPLACED BY L-LYSINE
TETRAPEPTIDE MAY BE FURTHER MODIFIED IN OTHER BACTERIA
PROCARYOTIC CELL ORGANIZATION & STRUCTURE
MAJOR STRENGTH OF CELL
WALL COMES FROM
PERIODIC CROSS
LINKINGBETWEEN THE
THIRD & FOURTH AA ON
ADJACENT TETRAPEPTIDE
CROSS-LINKING MAY BE
EITHER DIRECTLY (AS IN
MOST GM NEGATIVE CELLS)
OR VIA A PENTA-GLYCINE
LINK (AS IN MANY GM
POSITIVE CELLS)
PROCARYOTIC CELL ORGANIZATION & STRUCTURE
CROSS-LINKING MAY BE EITHER DIRECTLY (AS IN MOST GM
NEGATIVE CELLS) OR VIA A PENTA-GLYCINE LINK (AS IN MANY GM
POSITIVE CELLS)
NOT ALL PROKARYOTES HAVE PEPTIDO- GLYCAN IN THEIR
CELL WALLS:
ARCHAEA INSTEAD HAVE CELL WALLS COMPOSED OF
POLYSACCHARIDES, GLYCOPROTEINS & PROTEINS. THEY
DO NOT HAVE NAM IN THEIR WALLS;
MYCOPLASMA, WITH NO CELL WALLS, HAVE CELL
MEMBRANES WITH STEROLS TO PROVIDE STRENGTH
PROCARYOTIC CELL ORGANIZATION & STRUCTURE
IN GM POSITIVES PEPTIDOGLYCAN MAY BE AS
MUCH AS 40 LAYERS THICK
MOST OF THE CELL WALL (90%) MAY BE MADE
UP OF PEPTIDOGLYCAN, BUT THE REMAINDER
MAY BE OF ACIDIC POLYSACCHARIDE CALLED
TEICHOIC ACID (THEY ARE NEGATIVELY
CHARGED MOLECULES)
PROCARYOTIC CELL ORGANIZATION & STRUCTURE
GM NEGATIVES HAVE
THINNER CELL WALLS (A FEW
LAYERS THICK AND APROX. 520% OF ENVELOPE). INSTEAD
THEY HAVE AN OUTER
MEMBRANE STRUCTURE
SIMILAR TO THE CELL
MEMBRANE, BUT THE
COMPOSITION IS SLIGHTLY
DIFFERENT:
LIPOPOLYSACCHARIDE (LPS)
MAKE UP ABOUT 40% OF THE
OUTER LIPID BI-LAYER.
PROCARYOTIC CELL ORGANIZATION & STRUCTURE
O-SIDE CHAIN
COREPOLYSACCHARIDE
LIPID A
O SIDE: CHAIN VARIES DEPENDING ON THE BACTERIUM
CORE POLYSACCHARIDE: RELATIVELY CONSTANT COMPOSITION
LIPID A COMPOSED: OF GLYCOLIPIDS ASSOCIATED WITH TOXIC ACTIVITY IN GRAMNEGATIVE BCTERIUM
PROCARYOTIC CELL ORGANIZATION & STRUCTURE
PROCARYOTIC CELL ORGANIZATION & STRUCTURE
CELL WALL OF THE ACID-FAST BACTERIA
MYCOBACTERIA
THICK WALL LIKE THAT OF GM
POSIIVES.
PEPTIDOGLYCAN IS LESS &
ABOUT 60% LIPID.
THE LIPID MAKES THE BACTERIA
IMPERMEABLE TO MOST STAINS
AND PROTECTS IT FROM ACIDS
AND ALKALIS
CARBOLFUCHSIN BINDS
CYTOPLASM & RESIST ACIDALCOHOL DESTAINING.
SLOW GROWTH OF BACTERIA
DUE TO INEFFICIENT ENTRY OF
NUTRIENTS INTO THE CELL;
LARGE AMOUNTS OF ENERGY
MUST BE EXPENDED TO TAKE UP
NUTRIENTS.
PROCARYOTIC CELL ORGANIZATION & STRUCTURE
THE IMPORTANCE OF CELL ENVELOPES IN PRESERVING THE
STRUCTURAL INTEGTITY OF BACTERIA IS ILLUSTRATED THROUGH
THE LABORATORY CONSTRUCTS PROTOPLASTS & SPHEROPLAST
(CELLS WITHOUT MUREIN).
PROTOPLAST= GRAM POSITIVE CELLS WITHOUT MUREIN
SPHEROPLAST= GRAMNEGATIVE CELLS WITHOUT MUREIN (RETAIN
OUTER MEMBRANE)
LYSOZYME OR PENICILLIN USED TO CREATE THESE CELLS. THEY
SURVIVE ONLY IN ISOTONIC SOLUTIONS
PROCARYOTIC CELL ORGANIZATION & STRUCTURE
THE CELL WALL OF THE ARCHAEA
THE PROCARYOTES SURVIVE IN EXTREME ENVIRONMENTS (HIGH
SALT, TEMPERATURES, AND pH EXTREMES)
CONSIST OF BOTH GRAM POSITIVE AND GRAM NEGATIVE CELLS
THEY DO NOT HAVE MURAMIC ACID OR D-AMINO ACIDS.
- SOME ARCHAE HAVE A MOLECULE CALLED
PSEUDOPEPTIDOGLYCAN (REPEATING UNITS OF NAG AND NACETYLTALOSAMINURONIC ACID AND L-AMINO ACIDS (NOT
THE D-AMINOACIDS FOUND IN TRADITIONAL PEPTIDOGLYCAN).
- OTHERS HAVE SURFACE MONOLAYER OF PROTEINS OR
GLYCOPROTEINS & LACK PSEUDOMUREIN.
-OTHERS HAVE NO WALLS; CYTOPLASMIC MEMBRANE IS THE ONLY
CONSTITUENT OF THE ENVELOPE
-BETWEEN THE ALTERNATING CARBOHYDRATES IS BETA(1,3) [NOT
BETA(1,4) OF PEPTIDOGLYCAN] AND IT IS RESISTAN TO LYSOZYME.
PROCARYOTIC CELL ORGANIZATION & STRUCTURE
PERIPLASMIC SPACE: GAP BETWEEN PLASMA MEMBRANE AND THE
CELL WALL.
MOST EASILY OBSERVED IN GM-NEGATIVES. LESS DEFINED IN GMPOSITIVES
ACTIVE AREA OF CELL METABOLISM WITH HYDROLYTIC ENZYMES,
TRANSPORT PROTEINS; AND CELL WALL BUILDING BLOCKS.
NOTE DIFFERENCES
IN THE SIZE OF THE
PERIPLASMIC SPACE
PROCARYOTIC CELL ORGANIZATION & STRUCTURE
GLYCOCALYX: REFERS TO ALL POLYSACCHARIDE-CONTAINING SUBSTANCES
FOUND OUTSIDE THE CELL WALL (I.E., CAPSULE OR SLIME LAYER OR
GLYCOCALYX)
THE CAPSULE:
EXTERNAL TO THE ENVELOPE & PRESENT IN SOME BACTERIA (NOT ALL
MEMBERS OF A SPECIES MAY HAVE CAPSULES)
A LOOSE GEL, COMPOSED OF POLYSACCHARIDE, PROTEIN, OR ONLY
GLYCOPROTEINS
PROTECTS CELL FROM DESSICATION, NUTRIENT LOSS AND PHAGOCYTOSIS
MAY BE VISUALIZED BY QUELLUNG RXN (SPECIFIC ANTIBODIES BIND TO
CAPSULE & INCREASE REFRACTIVITY & CAPSULE APPEARS SWOLEN)
SLIME LAYER (GLYCOCALYX):
THINNER THAN CAPSULE, AND WHEN PRESENT PREVENTS CELLS FROM
DRYING OUT & TRAPS NUTRIENT.
POLYSACCHARIDE ARRANGESD AS FIBROUS MATRIX
ALSO ALLOWS BACTERIA TO ADHERE TO EACH OTHER AND OTHER OBJECTS
(EG., BACTERIA IN DENTAL PLAQUE ON TOOTH SURFACE)
PROCARYOTIC CELL ORGANIZATION & STRUCTURE
PROCARYOTIC CELL ORGANIZATION & STRUCTURE
OTHER EXTERNAL STRUCTURES:
FLAGELLA
RESPONSIBLE FOR MOTILITY
USED IN CHEMOTAXIS (MOVEMENT TO OR AWAY FROM SUBSTANCES
IN THEIR ENVIRONMENT) OR PHOTOTAXIS
MAY BE ARRANGED DIFFERENTLY DEPENDING ON SPECIES
SINGLE FLAGELLUM = MONOTRICHOUS
ONE FLAGELLUM AT EACH POLE = AMPHITRICHOUS
TWO OR MORE FLAGELLA AT ONE OR BOTH POLES =
LOPHOTRICHOUS
FLAGELLA ALL OVER THE SURFACE = PERITRICHOUS
AMPHITRICHOUS
MONOTRICHOUS
LOPHOTRICHOUS
PERITRICHOUS
PROCARYOTIC CELL ORGANIZATION & STRUCTURE
FIMBRIA & PILI (SOMETIMES USED INTERCHANGBLY)
FIMBRIA
- SHORTER AND STRAIGHTER THAN FLAGELLUM
- FIMRAE MAY BE EVENLY DISTRIBUTED OVER ENTIRE SURFACE USED FOR
ATTACHMENT (EG., NEISSERIA GONORRHOEA USE THEM TO ATTACH TO
MUCOU MEMBRANES AND CAUSE DISEASE)
PILI
- USUALLY LONGER THAN FIMBRIAE; NUMBER ONLY 1 OR 2/CELL
- USUALLY USED IN DNA TRANSFER DURING CONJUGATION