Microbiology Part 1

Microbiology Part 1

DOMAINS
1.    Archaea	Include prokaryotes with cell walls that are biochemically different from the bacteria Inhabit extreme environments of heat, cold ph or salts NOT MEDICALLY IMPORTANT
2.    Eukarya E.g. FUNGI, PROTOZOA, ALGAE etc I. LIVING   A.   FUNGI- classified: type of reproductive structures or lack of it 1.    Ascomycota (ascus)- Candida, histoplasma 2.    Basidiomycota (basidium)Cryptococcus 3.    Zygomycota (zygote) Rhizopus 4.    Deuteromycota (asexual, fungi imperfecti) Coccidioides   B. PROTOZOA- unicellular, NON-PHOTOSYNTHETIC       Classified by: Motility   1.    Mastigophora (flagellates) – Giardia 2.    Sarcodina (amoeba) – Entamoeba 3.    Ciliophora ( ciliates)- Balantidium 4.    Sporozoa (nonmotile) – Plasmodium     C. Bacteria – contain variety of PROKARYOTES include G+ and Gram -     II. NON-LIVING A.   Viruses     Classified by: 1.    Capsid structure 2.    Type and strandedness (DNA or RNA; single or double) B.   PRIONS- infectious proteins  are implicated in some spongiform encephalopathies      Ex: mad cow disease, Creutzfeldt- Jakob and kuru

 

 

STAINING of Bacteria
1.    Simple Stain	Single dye Ex, safranin, gentian violet
2.    Gram stain	Differential staining Gram +(purple) and Gram – (pink)
3.    Acid Fast Stain	Stains cells that have OUTER LAYER OF A WAXY LIPID acidfast (but not the cells that lack that layer or those non-acid fast)
4.    Spore stain	Uses HEAT for dye to enter the SPORE
5.    Capsule stain	Two(2) dyes  are used to stain the cell and the background, ALLOWING THE VISUALIZATION OF the unstained capsular material

 

Bacterial CELL SHAPE AND ARRANGEMENT
1.    Cocci	Spherical In chains Streptococcus pyogenes In pairs or diplococcic Sterptococcus pneumonia                  Neisseria gonorrheae In clusters or sptahylococci Packets of four or eight Sarcinae
2.    Bacilli	Cylindrical , rod-shaped Pseudomonas Escherichia
3.    Coccobacilli	Short, rounded rods Brucella
4.    Spirochetes and spirilla	Helical, corkscrew Treponema pallidum NOTE: Spirochetesàflexible helicals Spirilla à rigid
5.    Fusobacteria
6.    Filamentous , branching	Mold like bacteria Actinomyces bovis
7.    Vibrios	Comma shaped Vibrio cholerae
8.    PLEOMORPHIC	EXIST IN VARIED FORMS Haemophilus Legionella Corynebacterium

 

STRUCTURE OF PROKAYOTES
1.    NO internal membrane bound organelles		2.    YES Binary FISSION
3.    NO True Nucleus		4.    70s PROTEIN SYNTHESIS
		5.    YES Double stranded DNA, nucleoid is the area
External Structures
1.    Capsule and slime layer		Capsule- adherent surface coat Made up of long chains of peptides or carbs Antigenic differences among capsules can e used to identify strains. ( Sterptococcus pneumonia) 1.     Polysaccharide in nature, but Bacillus is a     POLYPEPTIDE   If the polysaccharide is NOT ADHERENT—called SLIME LAYER   If smooth colonies become roughà CAPSULE LOSS, loss of virulence. Capsular material is IMMUNOGENIC, induce prdoction of antibodiesà act as OPSONINS to enhance PHAGOCYTOSIS (opsonisation)
2.    Flagella		-          Proteinaceous, helically coiled organs used for movement that extend outward from the cytoplasm through the cell wall into the environment. -          COMPOSED OF FLAGELLIN—a protein called  HANTIGEN
3.    PILI (fimbriae)		Proteinaceous, shorter than flagella Hair like extensions -          COMPOSED OF: protein called PILIN or FIMBRILIN -          More common in GRAM NEGAtive
1.    Cell wall	Rigid General shape provider COMPOSED OF: BASIC PEPTIDOGLYCAN LAYER Which in turn repeating disaccharide units (a polymer of N-acetylglucosamine and Nacetylmuramic acid), Pept idoglycan is the basic layer of the cel l wall in both gram-posit ive and gramnegat ive organisms. I t provides a r igid f ramework that is suscept ible to the act ion of lysozyme. Gram-posi tive cel ls are def icient in l ipids; however , gram-negative cel ls are rich in complex l ipids (e.g. , l ipopolysacchar ide) . Both types of cell wal ls have cross-l inks between polysacchar ides.   BASIS OF GRAM POSITIVE OR GRAM NEGATIVE   GRAM POSITIVE (+) 1.    Thick wall 2.    90% peptidoglycan 3.    Has TEICHOIC ACID (glycerol or ribitol)   GRAM NEGATIVE (-) 1.    Thin peptidoglycan layer 2.    NO Teichoic acid 3.    Outer membrane - hydrophobic diffusion barrier n  Contains phospholipid with protein channel called PORINS n  LPS or ENDOTOXIN  or lipopolysaccharide- TOXIC and ANTIGENIC (O antigen) *3 parts 1. Lipid A- toxic portion ,cause non specific inflammation 2. Core polysaccharide 3. O- specific side chain
2.    Periplasmic Space	Area between cell wall and cytoplasmic membrane
3.    Cytoplasmic Membrane	Phospholipid bilayer matrix of fatty acid core (hydrophobic) and glycerol phosphate (hydrophilic) TRANSPORTATION of nutrients
INTERNAL STRUCTURES
1.    Storage granuoles
2.    Ribosomes	Cellular units that synthesize protein by the translation of the messenger RNA base sequences into amino acid protein sequences. 70s units unlike eukaryotic cells; not assoc with Rough ER and mitochondria
3.    Nucleoid	Double stranded , supercoild, circular DNA molecule
4.    Plasmids *some bacteria have	DNA pieces outside chromosome Contain info for heavy metal and antibiotic resistance Carry genetic elements called “TRANSPOSONS”   The chromosome carries all of the genes essential for growth, whereas plasmids are extrachromosomal, double-stranded, circular pieces of DNA that carry optional genes that add extra proper ties.

 

Microbial Physiology
Nutritional types
1.    AUTOTROPHS	Sole/ main energy source: CARBON DIOXIDE or CARBON   Photo-autotrophs: Light Source Chemo-autotrophs: Oxidize organic or inorganic compounds to produce energy
2.    Heterotrophs	ORGANIC COMPOUNDS:  main source   Photo-heterotrophs Chemo-heterotrophs
3.    Prototrophs	Parent cells that have no special nutritional requirements; same nutrients needed as the rest of their family
4.    AUXOtrophs	Mutated So that they cannot synthesize the same essential nutrients as their parent cell
5.    Subsets	1.    Holophytic- nutrients must be in SOLUBLE DIFFUSIBLE FORM 2.    Holozoic- NEED complex nutrients; 3.    Saprophytic- nutrients from dead or decaying organic matter 4.    Parasitic- obtain from and at expense of living organism (human pathogens)
NUTRITIONAL REQUIREMENTS SIX (6) MAIN ELEMENTS
1.    Carbs 2.    Lipid 3.    Protein 4.    Nucleic acids	P. S.- C,H,O,N

 

TEMPERATURE RELATIONS
1.    Psychrophile	Optimal growth at 15 C or less. Grows well at 0 C Max 20 C
2.    Mesophile	Optimal growth 20-45 C Minimum: 15 to 20 C Max 45 C (human pathogens)
3.    Thermophile	55 C or greater Minimum growth at approx. 45C
OXYGEN REQUIREMENTS
1.    Aerobes	Ability to grow with atmospheric Oxygen
	a.    Obligate AEROBES- depend completely for O to grow b.    Facultative AEROBE- may grow whether or not there is O
2.    AN-AEROBES	Ability to grow WITHOUT OXYGEN a.    Obligate ANAEROBE--DO NOT TOLERATE O…DIE with its presence Lack catalase and superoxide dismutase, which protect cells from the destructive oxidizing capabilities of H2O2 and superoxide ions , which are normally produced in aerobic conditions   b.    Facultative ANAEROBES—DO NOT REQUIRE O TO GROW but Grow BETTER with its presence PS. Facul tat ive organisms can grow wi thout ai r and make either a fermentative or a respi ratory set of enzymes, depending on the condi tions.
3.    MICROAEROPHILES	Require LESS O levels below normal atmospheric pressure for growth (e.g. Helicobacter pylori)
4.    Capnophiles	Reuire HIGHER LEVELS OF CARBON DIOXIDE than are found ar normal Atm. Pressures for growth e.g. Neisseria sp Streptococcus pneumoniae
Bacterial Growth Curve (binary Fission) y- log of cell number x- time
1.    Lag	Transition period -          Replicating DNA and enzyme -          Cells –increasing size not numbers -          @ this stage: CELLS MOST PERMEABLE
2.    Logarithmic  (LOG) phase	Division at constant and maximal rate No. of cell increase in GEOMETRIC PROGRESSSION Generation time: 15-20 minutes E.coli Hours Mycobacterium @this stage: since cell walls is being synthesized rapidly, bacterial cells are MOST SUSCEPTIBLE TO CELL WALL INHIBITORS
3.    Stationary Phase	Growth and death rates nearly EQUAL @ this stage: CELLULAR METABOLITES ARE POLLUTING the ENVIRONMENT
4.    Death Phase	Conc of viable cells decreases because of ACCUMULATION OF TOXIC WASTES AND AUTOLYTIC ENZYMES