Microbiology: Bacterial Structures, Cell Walls, and Staining Techniques

Microbiology

The study of microbes (organisms and viruses usually only visible under a microscope)

virulence

how easily a pathogen can infect and cause disease in a host

avirulent

microbe is harmless due to loss of virulence

Monotrichous

single flagellum at one end

Lophotrichous

truft of flagella emerging from one side

Amphitrichous

flagella at both ends of cell

Peritrichous

flagella dispersed all over surface of cell

Periplasmic Flagella

flagella enclosed in the periplasmic space between the outer membrane and the cell wall peptidoglycan

Sex Pilus

Function to join bacterial cells for horizontal DNA transfer called conjugation

Hamus (plural = hami)

grappling hook

Glycocalyx

Coating of molecules external to the cell wall,made of sugars and/or proteins

Slime layer

type of glycocalyx that is loosely organized and attached

Capsule

type of gylocalyx that is highly organized, tightly attached

Functions of the Glycocalyx

Protect cells from dehydration and nutrient loss, Inhibit killing by white blood cells by phagocytosis,contributing to pathogenicity

Bacterial cell walls are composed of

peptidoglycan

1) N-acetylmuramic acid (M). 2) N-acetylglucosamine (G)

peptide cross-links hold adjacent N-acetylmuramic acid molecules togetheron parallel glycan chains)

Gram-Positive (G+) Cell Wall includes

teichoic acid and lipoteichoic acid: function in cell wall maintenance and enlargement during cell division; move cations across the cell envelope; stimulate a specific immune response

in gram - Outer membrane contains

lipopolysaccharides (LPS)• Lipid portion (endotoxin) may become toxic when released during infections

porin proteins

regulate molecules entering and leaving cell; TRANSPORT

mycolic acid

Gram-positive cell wall structure enriched with the waxy lipid

acid-fast stain

used for diagnosis of infections

caused by these microorganisms

Mycoplasma

no cell wall, Cell membrane is stabilized by sterols

Glycocalyx

"Sweet cup" composed of polysaccharides and/or polypeptides

flagella

Long whip, Made of tubulin in eukaryotes, Made of flagellin in bacteria

Axial filaments

Made of tubulin in eukaryotes

Fimbriae

Bristlelike projections found in quantities of 100 or more

Pili

fibril structures extended outwards from the cell, composed of proteins called pilins

The cell membrane is made up of

bilayer of phospholipids and proteins

Functions of prokaryotic cell membrane

selectively permeable barrier, allows secretion, enzymes, invaginations(infoldings), receptors

Bacterial flagella are

anchored to the cell by a basal body

Which cellular structure is important in classifying a bacterial species as Gram positive or Gram negative

cell wall

Dipicolinic acid is an important component of

endospores

Which of the following is smallest

nanometer

T/F A bacillus is a bacterium with a slightly curved rod shape

false ( vibrio)

T/F If you were to view staphylococci, you should expect to see clusters of cells

true

best describes stiff, spiral-shaped prokaryotic cells

spirilla

Endospores

remain alive for decades, can remain alive in boiling water, exist in a state of suspended animation, All of the above are correct.

Flexible spiral-shaped prokaryotes are

spirochetes

The presence of mycolic acid in the cell wall characterizes

Mycobacterium

Taxis

movement in response to an environmental signal

Non protruding flagella

perplasmic/endoflagella

Endoflagella form

axial filaments that produce a corkscrew motion

fimbriae(adhesive pili)

small bristle like fibers sprouting off the surface of cells that attach to mucus membranes

Biofilms

bacterial cells clump to form protective formation like plaque , implanted medical devices

Order of layers

1.glycocalyx 2. Cell wall 3. Periplasmic space 4. Cell membrane

lies directly below glycocalyx and also prevent osmotically induced cell lysis(death)

Cell wal

Outer leaflet

in gram neg, made up of lipopolysaccharides

Inner leaflet

in gram neg, made of phospholipids and protein

Mycobacterium and nocardia

contain peptidoglycan in cell walls and a waxy mycolic acid

Peptidoglycan is made up of

sugar and amino acids

L forms

bacteria that ordinarily contain a cell wall but have lost some or all of it at some point due to genetic mutation or exposure to chemicals

Protoplast

type of L form that is from G+ bacteria and has no peptidoglycan layer

Scheroplast

type of L form that is from G- bacteria and has a thin peptidoglycan layer but retaining outer membrane

Polar flagellation

the flagella are attached at one or both ends of the prokaryotic cell

Eukaryotic flagella are powered by

atp driven motor proteins that bend in a whip like manner

microtubules

Major internal structural components of eukaryotic flagella

shigella

Small abundance but still make a big impact

prochlorococcus

Big abundance

Microbiome

microbes associated with another organism at any given time in its life (live on you or in you)

pathogenic

Microbes that can cause disease via infection

Invasiveness

ability of a microbe to establish itself in/on a host

Toxigenicity

ability of a microbe to produce a toxin that weakens the host

Taxonomy

system of assigning formal scientific names and classification to organisms

Phylogeny

study of evolutionary relationships among living things

Binomial nomenclature

naming system that uses latinized genus and species

helical structure composed of a protein called flagellin. form protruding tail of flagellum

filament

curved tubular structure anchored to the cell by basel body

hook (sheath)

stack of rings fixed to hold the flagellum together

basal body

cell envelope

the external covering of the bacterial cell

polymers of glycerol and phosphate groups; anchored throughout peptidoglycan layer

teichoic acid

teichoic acids molecules bonded to lipids to anchor them in the phospholipid bilayer of underlying plasma membrane

lipoteichoic acid

cytoplasm

dense gelatinous intracellular region; composed of mostly water and has no nucleus

nucleoid

where prokaryotic cell genetic material is concentrated

plasmids

circular extra chromosomal molecules of dna

ribosomes

synthesize proteins

inclusions

aggregations of organic or inorganic material in a cell

Endospores

dormant round bodies produced by certain species of bacteria in response to adverse environmental conditions; provides protective covering around bacterial chromosome

core

innermost compartment of endospore; contains bacterial chromosomes

cortex

layer outside the core made of peptidoglycan in endospore

protein coat

several layers of protein that further help protect the spore and located exterior to the cortex

characteristics of spores

resistant to heat, light, chemicals, freezing

2 bacteria that form spores

bacillus and clostridium

metachromatic granules

phosphate reserves

Magnetosomes

magnetic fields

glycogen/PHB

carbon/ energy reservoirs

Gas vesicles

buoyancy control

spore locations within the cytoplasm

-central endospore(middle)

-subterminal endospore(off the edge)

-terminal endospore(end)

when favorable conditions arise for an exospore

germinate and reform a vegetative cell

diplococci

2 cocci together

tetracocci

group of 4 spherical cells

sarcina

eight spherical cells

staphylococci

grape cluster of spherical cells

streptococci

linear chain of spherical cells

diplobacilli

two rod shaped side by side

Streptobacilli

linear chain of rod shaped cells

palisade

picket fence of rod shaped cells