Chapter 4 Bacteria + Archaea Flashcards
Packaging of DNA in Bacteria and Archea
Nuclear material that is free in cytoplasm
Bacteria + Archaea Internal Structure
have no membrane-bound organelles
Bacteria cell appendages
Flagella, Pilus, Nanowires and Fimbriae
Bacteria Cell Surface Layers
S layer and Glycocalyx
Bacterial cell boundary
Cell wall and cytoplasmic membrane
Bacterial cell internal properties
cytoplasm, ribosomes, inclusions, nucleoid/chromosome, cytoskeleton, endospore, plasmid, Microcompartments
Nanowires/nanotubes
Membrane extensions that allow bacteria to transmit electrons or nutrients to other bacteria or onto environmental surfaces
Endospore formation
-triggered by lack of nutrients
-usually Gram-positive bacteria
-enables bacteria to lie dormant for extended periods
-bacterium divides within its cell wall
Bacteria carry out all life activities which are?
-Reproduction
-Metabolism
-Nutrient processing
bacteria acting as a group
-Colonies
-Biofilm
Bacterial shapes
-Coccus (round)
-Coccobacillus (round rod)
-Bacillus (rod)
- Vibrio (Curved)
-Spirillum (spiral)
-Spirochete (tight spiral)
Pleomorphism
-Variations in size and shape among cells of a single species
Cocci Grouping
-Coccus (single sphere)
-Diplococci (pairs)
-Tetrad (groups of four)
- Staphylococci (irregular clusters)
- Streptococci (chains)
- Sarcina (cubical packet of 8, 16 or more)
Bacilli Arrangements
-Bacillus (single)
- Diplobacilli (Pairs of cells w/ ends attached)
-Streptobacilli (chains of cells)
-Palisades (side by side row of cells)
Bacterial Appendages for motility
-Flagella: rotates 360 degrees
-Axial filaments
Bacterial appendages for attachment or channel formation
PIlus/pili
Fimbria/fimbriae
nanowires
Three distinct parts of flagella
-Filament :composed of protein inserted into hook
-Hook: curved and tubular, attached to basal body
-Basal body: composed a rod and rings anchored through the cell wall to the cytoplasmic membrane and the outer membrane.
Flagellar arrangement
-Polar: Monotrichous, Lophotrichous, Amphitrichous
-Peritrichous
Monotrichous Flagella
Single flagellum
Lophotrichous flagella
Small bunches or tufts of flagella
Amphitrichous flagella
Flagella at both poles of the cell
Peritrichous flagella
Dispersed randomly over the surface of the cell
Run and Tumbles
Run: counterclockwise movement of flagellum in a straight line
Tumble: reverses direction causing cell to stop and change course
Positive Chemotaxis
Movement of a cell toward a favorable chemicle stimulus
Negative Chemotaxis
Movement of a cell away from repellent or harmful compound
Phototaxis
Movement toward light
Axial filament
-Motility appendage for spirochetes
-They are internal flagellum enclosed between the cell wall and the cytoplasmic membrane
-Twisting or flexing movement
pili/pilus
-Mostly found in Gram neg bacteria
-Used in Conjugation (partial transfer of DNA from one cell to another
-production of Pilus is controlled genetically
Fimbriae
-Bristle like fibers sprouting off the surface of some bacteria
-Tendency to stick to each other and surfaces
-Responsible for biofilms
(E. Coli)
S layer on a bacteria
-Thousands of copies of a single protein linked together like armor.
-Provides protection from environment
-Only produced in hostile enviroments
Glycocalyx (key to biofilms)
Repeating polysaccharide units that may or may not include protein
-Aids in protection and adhesion
-Forms a slime layer or capsule
Slime layer
-Forms loosely around cell
-Protect cell from loss of water and nutrients.
Capsule
-More tightly bound to cell than a slime layer
-Denser and thicker than slime layer
-Protects pathogenic bacteria against phagocytic white blood cells
Phagocytes
White blood cells that engulf and destroy foreign cells
Biofilm
an assemblage of surface-associated microbial cells that is enclosed in an extracellular polymeric substance matrix
The cell envelope
-Made of peptidoglycan
-Provides strong structural support
-Cell wall
-Cytoplasmic membrane
-Outer membrane (Gram negative)
Gram Positive Cell Envelope
-Thick cell wall composed of peptidoglycan (20 to 80 nm thick)
-Contains teichoic and lipteichoic acid
-Inner cytoplasmic membrane
Gram Negative cell envelope
-Outer membrane: more rigid
-Thin cell wall: greater sensitivity to lysis, single thin sheet of peptidoglycan 1-3 nm thick
-Inner cytoplasmic membrane
Acid-fast bacteria
-Bulk of cell wall of Myocobacterium (waxy lipds)
-Contributes to pathogenicity of these organisms
-resistant to certain chemicals and dyes
Acid fast stain commonly used to diagnose
tuberculosis and leprosy
Mycoplasmas
-Lack a cell wall
-Membrane stabalized by sterols and resistant to lysis
-Pleomorphic shape
Cytoplasmic membrane structure
-5-10 nm flexible sheet molded around the cytoplasm
-Phospholipid bilayer embedded w/ proteins
-Contain sterols
Cytoplasmic membrane functions
-Energy reactions
-Nutrient processing
-Synthesis
-Regulate transport of nutrients and wastes in and out of cell
Outer membrane (Gram Neg)
-Outer phospholipid bilayer w/ proteins and polysaccharides
-Lipopolysaccharides (Contains endotoxins stimulates fever and shock reactions)
-Lipoproteins ( anchors outermembrane to peptidoglycan)
-Porin proteins (allows small molecules in, block entrance and act as defense against antibiotics)
Bacterial Chromosome
-Single circular strand of DNA
-Aggregated in a dense area called nucleoid
-DNA Tightly coiled around basic protein molecules to fit cell compartment
Plasmid
-Nonessential pieces of DNA
-Double stranded circles of DNA
-Duplicated and passed on to offspring during replication
-Confer protective traits
-Important agent in genetic engineering
Ribosomes
-Made of RNA and protein
-Is the site of protein synthesis
-Dispersed throughout the cytoplasm, often found in chains
-Size is measured in Svedburg (S) units
Size of Bacterial ribosomes
70S units (Svedburg)
Size of Eukaryotic ribosomes
80S units (Svedburg)
Inclusion bodies
-Storage site for nutrients during periods of abundance
-Bacteria take from stocks during low periods of nutrition
The Cytoskeleton
-Arranged around the cell just under the cytoplasmic membrane
-Contributes to cell shape
-Potential target for antibiotic development
Bacterial endospores
-Spore formation indused by environmental conditions (depletion of nutrients, carbon, nitrogen)
-Withstands hostile environments
-Inert, resting position
Bacterial two phase life cycle
-Vegetative cell : metabolically active
-Endospore: Resting
Diseases related to spore persistence
-Bacillus anthracis: anthrax
-Clostridium tetani : tetanus (lockjaw)
- C. botulinum: botulism
-C. difficile: colitis
Bacteria and archea similarities
-Unicellular, no defined nucleus, asexual reproduction
Bacteria and Archaea differences
Cell wall structure, cell membrane structure, enzymes, generation genetic material
The Archaea
Bergey’s Manual of Systmic Bacteriology
-Comprehensive view of bacterial and archaea relatedness
-Combines phenotypic information with rRNA sequensing for classification
Bergey’s Manual of Determinative Bacteriology
-Based on phenotypic characteristics only
-Used by microbiologists who need to identify bacteria but not know their evolutionary background
-Useful for students of medical microbiology
(Taxonomic scheme) 4 Major divisions of bacteria and archaea
-Gracilicutes: gram-neg cell walls, thin skinned
-Firmicutes: gram-pos cell walls, thick skinned
-Tenericutes: lack cell wall, soft
-Mendosicutes: archaea
Divisions in the Diagnostic scheme
-Gram pos
-Gram- neg
-Bacteria without a cell
Sub groups of the Diagnostic scheme
-Cell shape
-Arrangement
-Oxygen use
*Aerobic (use oxygen in metabolism)
*Anaerobic (don’t use oxygen in metabolism
*Facultative (may or may not use oxygen)
Staphylococcus
-Gram Positive
-Cocci in clusters or packets
-causes boils and skin infections
Streptococcus
-Gram Positive
-Cocci in pairs or chains
-Causes strep throat, dental caries
Bacillus
-Gram positive
-Endospore forming rods
-Anthrax
Clostridium
-Gram positive
-Endospore forming rods
-Tetanus
-Gas gangrene botulism
Mycobacterium
-Gram positive
-Tuberculosis
-Leprosy
Neisseria
-Gram Negative
-Aerobic cocci
-gonorrhea
-meningitis
Escherichia
-Gram neg
-faculative or anarobic rods and vibrios
-E coli
Salmonella
-Gram neg
-facultative or anaerobic rods and vibrios
-typhoid fever
Treponema
-Gram neg
-anaerobic rods
-syphilis
