Bacteria Flashcards
Unusual and chemically distinct cell wall that
lacks true peptidoglycan
Archaea
Part of the cell wall only found in bacteria
Peptidoglycan
Classifications of Archaea
MEPH
Methanogens - Convert CO2 and H2 into methane gas (CH4)
Extreme Halophiles - require salt to grow (uses red pigment eg. sunlight)
Psychrophiles - grow at very low temp/cold
hyperthermophiles - Grow at very high / hot temperature
Salt and acid tolerant
Characteristics used between bacteria and archaea in early years
shape, arrangement, growth,
characteristics, and habitats
Difference between bacteria and archaea in recent years
biochemistry, genetics, and
molecular traits
4 major divisions of taxonomic scheme
Gracilicutes - gram negative cell wall / thin skinned
Firmicutes - gram positive / thick and strong
Tenericutes - lack cell walls / soft
Mendosicutes - archaea
3 divisions of diagnostic scheme
Gram-positive
Gram-negative
Bacteria without cell walls
Subgroups of diagnostic scheme
• Cell shape
• Arrangements
• Oxygen usage
Aerobic – use oxygen in metabolism (aerobes)
Anaerobic – do not use oxygen in metabolism (anaerobes)
Facultative – may or may not use oxygen (facultative bacteria)
Activities of bacteria
Colonies- clusters
Biofilms – could cause some harmful effects to humans
What is bacteria capable of
- Reproduction
Binary fission – multiplication of single bacterium into millions
-Metabolism
-Nutrient processing
Average size of bacteria
1 micrometer
Size of nanobacteria
0.05 to 0.2 micrometer
100 to 750 μm
Largest bacterium
Found in South Africa
Can be seen by the naked eye
Thiomargarita namibiensis
Bacterial shapes
Coccus/cocci - oval (micrococcus luteus)
Bacillus/bacilli - rod/cylindrival streptobacillus sp.
Curved spiral vibrio cholera
Mo definitely shape or variation of bacteria
Pleomorphism
Types of cocci
Diplococci – pairs
- Neisseria sp. – causes gonorrhea and
meningitis in humans
- Streptococcus pneumoniae –
causes respiratory diseases
(pneumonia)
• Tetrads – groups of four
• Staphylococci and micrococci – irregular clusters
• Streptococci – chains of a few to hundreds
• Sarcina – cubical packet of 8, 16, or more cells
Types of bacilli
Diplobacilli – pairs of cells with their ends attached
o Klebsiella sp.
o Moraxella
o Coxiella burnetti
Streptobacilli – chains of cells
Streptobacillus moniliformis – responsible for causing the rat bite fever (present in saliva of rats)
• Coccobacilli – short and stumpy
Palisades – cells of a chain remain partially
attached and fold back, creating a side-by-side
row of cells (have picket-fence like shape)
Types of coccobacilli
Chlamydia trachomatis – causes chlamydia
Gardnerella vaginalis – cause
bacterial vaginosis among women
Haemophilus influenzae – cause respiratory diseases, especially in children
Type of palisades
Corynebacterium diphtheriae – causes diphtheria
Curved bacteria
Vibrio - comma shaped
Spirillium - helical and rigid
Spirochete - flexible and helical
Bacteria without cell walls
Pleumorphic
Mycoplasma species
Display extreme variations in shape due to lack of cell walls (can alter size and shape)
Their cell walls are softer
Mycoplasma
Two major appendages of bacteria
Flagella and axial filaments
- Provide motility / movement
Fimbriae, pili, and nanowires
- Provide attachment points or channels
Flagellar arrangements
Polar – flagella attached at one or both ends of the cell
- Monotrichous – single flagellum
- Lophotrichous – small bunches or tufts
- Amphitrichous – flagella at both poles of the cell
• Peritrichous – flagella are dispersed randomly over the surface of the cell
A special form of flagella for spirochetes
Periplasmic flagella
Two or more long coiled threads found in spirochetes
Axial filaments
Movement in response to chemical signals
Chemotaxis
Movement towards the light
Phototaxis
Appendages for attachement
Pili - adhesion but not locomotion
Fimbriae - adhesion but not locomotion
Flagella - also used for attachment
Small, bristle-like fibers sprouting off the surface
of certain species of bacteria
Composition varies, but most contain proteins
Fimbriae
use fimbriae to
adhere to epithelial cells
Escherichia coli
Long, rigid, tubular structure made of pilin protein
Only found in gram-negative bacteria
Used in conjugation
Pili
Surface coatings
S layer - produced in hostile environments / single protein linked
Glycocalyx - gelatinous
Slime layer - losee / prtects from loss of water
Capsule - tightly bound / denser thicker
Has a very thick
layer of cell wall /
peptidoglycans
Purple or blue stain
Crystal violet
Gram positive
Has a very thin
layer of peptidoglycans &
has an extra layer called the outer membrane layer
Pink or red
Safranin
Gram negative
Provides strong structural support to keep the cell from bursting or collapsing due to osmotic pressure
Primarily made up of peptidoglycans
Cell wall
Made up primarily of alternating chains of
proteins and sugars
Peptidoglycan
Gram positive cell wall
Teichoic and lipoteichoic acid
Lack cell wall structure of gram-positive or gram-
negative bacteria
Nontypical cell wall
Very long-chain fatty acid
Contributes to pathogenicity of these organisms
Provides stronger protection
Mycolic acid (cord factor)
used to diagnose tuberculosis and leprosy
Acid fast stain
Naturally lack cell wall
Membrane is stabilized by sterols / fatty acids
and is resistant to lysis
Mycoplasmas
Functions of cytoplasmic membrane
Energy reactions
Nutrient processing
Synthesis
Regulate transport
Stimulates fever and shock reactions
Endotoxins
Anchor the outer membrane to
peptidoglycan
Lipoproteins
Only allow relatively small molecules to
penetrate
Porin proteins
Prominent site for the cell’s biochemical and
synthetic activities
Cytoplasm
Single circular strand of DNA
Aggregated in a dense area called the nucleoid
DNA is tightly coiled around basic protein molecules to fit into the cell compartment
Bacterial chromosome
Nonessential pieces of DNA
Important for genetic engineering
Plasmids
Organelle that are not membrane bound
Made up of RNA and protein for protein synthesis
Ribosomes
Measurement of the relative size of cell parts through sedimentation during centrifugation
Svedberg units
Svedberg (S) units of bacterial And eukaryotic ribosomes
Bacterial - 70S
Eukaryotic - 80S
Storage site for nutrients during periods of abundance
Inclusion bodies
Long polymers of proteins similar to eukaryotic
actin
Potential target for antibiotic development
Cytoskeleton
Withstand hostile conditions and facilitate survival
• Can resist:
o Heating
o Drying
o Freezing
o Radiation
o Chemicals
Endospores
Two phase life cycle
- Vegetative cell - active
- Endospore - resting
Occurs when the bacteria has been exposed in
a hostile environment
Process of transformation from vegetative cell
to endospore
Sporulation
Process of transformation from endospore to
vegetative cell
Germination
Diseases to spore persistence
- Bacillus anthracis (cutaneous and inhalation anthrax)
- Clostridium tetani - tetanus
- Clostridium perfringens - infection of wounds
- Clostridium botulinum - botulism / infected cans or jars
Members cause boils, skin infections, sepsis
Staphylococcus
Species cause strep throat, dental caries, pneumonia
Streptococcus
Involved in wound infections
Peptococcus & Peptostreptococcus
Anthrax
Bacillus
Tetanus, gas gangrene, botulism
Clostridium
Erysipeloid
Lactobacillus, Listeria, and Erysipelothrix
Diphtheria
Corynebacterium
Tuberculosis, leprosy
Mycobacterium
Gonorrhea, meningitis
Neisseria
Dental disease
Veillonella
Pneumonia, burn infections
Pseudomonas
Pneumonia
Mycoplasma
Urinary infection
Ureplasma
