Microbiology Sammartano Chapter 9

1. Growth- increase in size and complexity
2. Reproduction- production of new cells or of a new individual. sexual/asexual
3. Responsiveness- ability to detect changes in external or internal environment and respond to them.
4. Metabolism- all chemical reactions that occur within a cell

Both are surronded by a plasma membrane (phospholipid bilayer) that defines their boundaries.
Both encode genetic information in DNA molecules.

Pro: no nucleus/ one circular chromosome/ no nucleolus/ small ribosomes (70s)/ cell wall contains peptidoglycan/ pili present/ reproduce asexually only.
Eukaryotes: true nucleus/ multiple, linear chromosomes (46 pair from male and female) / Nucleolus/ Larger Ribosomes (80s) Cell wall contains cellulose (algae) or chitin (fungus) / no pili/ reproduce asexually or sexually

Glycocalyx (sugar Coat) allows bacteria to stick to host. Composed of Capsule - Appears as extensive, tightly bound accumulation of gelatinous material adhering to cell wall or as a Slime layer – unorganized and loosely attached.
Composed of polysaccharide or polypeptide subunits.

– Enables certain bacteria to resist phagocytic
engulfment by white blood cells
– Enables some bacteria to adhere to
environmental surfaces to colonize and resist
flushing (rocks, human teeth)
– Protects against dehydration (dessication)

Streptococcus pneumoniae
– Pathogenic with capsule
– Nonpathogenic without capsule

Long filamentous
appendages that
function in propelling
the bacterium

Filament – rigid, helical
structure extending from cell
surface (flagellin protein)
– Hook – flexible coupling
between filament and basal body
– Basal body – a rod and series
of rings that anchor the flagellum
and the cytoplasmic membrane
molecular motor that enables
flagellum rotation

Monotrichous – single flagellum, at one pole
Amphitrichous – single flagellum at both ends of the organism
Lophotrichous – two or more flagellum at one or both poles
Peritrichous – flagella over entire surface
Atrichous – bacteria
without flagella (cocci rarely have flagella)

• Locomotion (for most of bacteria capable of
motilityClockwise rotation – tumbling motion that
changes direction of bacterial movement
• Counterclockwise rotation – long, straight or
curved runs without change in direction

H pylori (the causative agent for some forms of gastric ulcers in humans.

positive chemotaxis: movement towards chemical.
negative chemotaxis: movement away from chemical
positive phototaxis: movement toward light
negative phototaxis: movement away from light
Movement towards is usually because of sex or food. Away from would be because of predators.

Hair-like, tubule,
projections found in many
gram-negative bacteria
(shorter and thinner than
flagella); made of Pilin
protein
• Used for attachment, not
movement
• Found at poles and help
bacteria adhere to surfaces
– Neisseria/mucous
membranes
• Contribute to pathogenicity
Clinically significant in N gonorrhoeae and E coli

Longer tubulescomposed of pilin
• 1 – 10 pili present/bacteria that have them
• Conjugation (sex) pili
– Found only in certain
groups of bacteria
– Attaches two cells to
provide a pathway to
transfer genetic material
(conjugation)
– Important mechanism of
transferring antibiotic
resistance. The extra gene is used for antibiotic resistance.

Internal flagella found
only in spirochetes
• Composed of two -
>100 axial fibrils
(endoflagella) that
extend from both
ends of bacterium
between outer
membrane and cell
wall. Clinically significant: can bore through tissue as in Treponema pallidum (causative agent of syphilis) and B burgdorferi (lyme disease)

• 10 – 65 NAM/NAG
molecules joined in chain
(glycan)
• Rows linked by
tetrapeptides (4 amino
acids joined to NAM)
• D-amino acids! (this is
unusual)
• Parallel chains held
together by peptide cross
bridges
sugars in the body are in D form/ amino acids are in L form

• Very thick
peptidoglycan layer
(very rigid) (9.4a)
• Teichoic acids (alcohol
and phosphates)
– Lipoteichoic acid (span
peptidoglycan layer and
link to plasma
membrane)
– Wall teichoic acid –
linked to peptidoglycan
layer

• Very few layers of
peptidoglycan (9.4b)
• Outer membrane – LPS,
lipoproteins, phopholipids
(barrier; protection)
• Periplasmic space
– Fluid-filled space between
outer and plasma membrane
– Contains peptidoglycan layer
– Active area of cell
metabolism
– Contains digestive enzymes
and transport proteins

Endotoxin

(toxicity or poisining to pt seen as flu symptoms/ DIC

• Mycoplasma (do not confuse with Mycobacterium)
– Do not have cell walls
– Unique plasma membranes (sterols)
• L-forms
– Bacteria that have cell walls and then lose their ability to
make them
– May play a role in recurrent chronic disease
– Sometimes results from treatment with antibiotics specific
for cell wall destruction (Mycobacterium paratuberculosis
– Chron’s disease)
• Archaea
– Lack cell walls OR
– Unique cell walls (no peptidoglycan)

they turn gene genesis off making it difficult to treat.

• Organized, layered systems of bacteria attached
to surface
• Bacteria organized in biofilms act differently than
individual ones
• Bacteria in biofilms ~ 2/3 of bacterial infections
in humans
• Important for health care
– Impede or inhibit antimicrobial drugs
– Allow bacteria to retain nutrients
– “Frustrated phagocytosis” impedes wound healing

• Phospholipid bilayer embedded
with proteins
• Barrier between the cytoplasm
and outside environment
• Selectively permeable conduit
• Defines the boundary of the
cell
• Amphipathic (both hydrophilic
and hydrophobic components)
Highly organized &
dynamic
• Location of variety of
critical metabolic
processes
(respiration, lipid
synthesis, etc.)

• Substance inside the plasma membrane
• 80% water; ~ 1000 different enzymes
• Proteins, carbohydrates, lipids
• Inorganic ions
Areas
• Nuclear area
• Many ribosomes
• Inclusions

****Sites of protein synthesis (translation)
• Two subunits
• Protein + rRNA
• Streptomycin inhibits protein synthesis by attaching to
30S subunit
• Eryhtromycin attaches to 50S (30S +50S=70S)

• Reserve deposits of lipids,
startch or compounds
containing nitrogen,
phosphate or sulfure
• Poly-β-hydroxybutyrate
• Glycogen
• Sulfur
• Polyphosphate
• Magnetosomes

– Single, continuous,
circular doublestranded
DNA
– Contains genetic
information for
structure and function
– Chromosome attached
to plasma membrane

– Extrachromosomal,
small, circular, ds DNA
– Drug resistance genes
– Heavy metal
resistance

• Endospore – unique type
of dormant cell
– Highly durable dehydrated
cells
– Formed internally
• Survive extreme heat,
dehydration, UV,
radiation, toxic chemicals
– Thermoactinomyces
vulgaris (Elk Lake, MN)

k

Protects the cell from the environment

Peptidoglycan

repeating NAG NAM molecules

Teichoic acids

go only halfway through the cell wall

go completely through the cell wall

are involved in respiratory infections

have an outer membrane

translocation proteins

has no cell wall

contribute to infections, are considered virulence factors, and are found on S pyogenes

is found only in certain Gram-positive bacteria

part of the endotoxins of gram-negative bacteria

used to identify certain bacteria

Phospholipid bilayers

the glycocalyx

causes bacteria to become more infective

staying in the host

All of the above

the same as flagella

Peritrichous flagella

a phospholipid bilayer

go all the way through the membranes

Extrachromosomal pieces of DNA

are involved in protein synthesis

are resistant to antibiotics

resistant to heat