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bacterial cytology
bacterial cytology
55
Microbiology
Professional
03/01/2013

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Term
Prokaryotes
Definition

no nuclear membrane

single circular chromosome (haploid)

transcription and translation occur simultaneously (coupled)

respiration is via the cytoplasmic membrane

no cytoplasmic membrane bound organelles

 

Term
eukaryotes
Definition

nucleus is bound by nuclear membrane

multiple chromosomes-DNA associated with histones (diploid)

transcription occurs in nucleus and mRNA moves into cytoplasm for translation

respiration via mito

cytoplasmic membrane bound organelles

Term
whats in the cell envelope
Definition

cytoplasmic membrane

cell wall (peptidoglycan)

capsule

outer membrane

Term
cytoplasmic membrane
Definition

lipid bilayer

semi-permeable

70% protein

30% phospholipids

No sterols -exception is mycoplasma

 

Term
membrane function
Definition

transport

site of attachment for enzymes

DNA replication

Electron Transport (energy generation)

Oxidative phosphorylation

Cell wall biosynthesis

Term
periplasmic space
Definition

found only in gram negative bacteria

space between outer and cytoplasmic membrane

contains degrative enzymes, nucleases, phosphatases, penicillinases

Term
cell wall
Definition

rigid

give bacteria its shape

protects from osmotic lysis

target for antibiotics

Term
glycocalyx
Definition

viscous material extending from the bacterial cell

adhesive polymer

secreted by bacteria

 

Term
slime layer (S)
Definition
glycocalyx loosely attached to the cell wall
Term
capsule
Definition

glycocalyx bound tightly to the cell wall

covers cell surface

composed of polysaccharide polymers except for Bacillus subtilis; used in certain vaccines

has K antigens

 considered a virulence factor

Term
what is Bacillus subtilis capsule made of?
Definition
poly-D-glutamic acid
Term
capsule function
Definition

antiphagocytic

hinders opsonization

mediates adhesion of bacteria to human tissues

helps in lab id via Quellung reaction

Term
k antigens
Definition
determines serological types
Term
Pili
Definition

hairlike structures on the surface of bacteria

smaller diameter than flagella

 composed of pilin (pilE)

Term
Capsules are considered virulence factors in what bacteria
Definition

pneumococci

meningococci

Term
Pili are important virulence factors in what bacteria
Definition

E. Coli

N. gonorrhoeae

Term
F- pili
Definition
involved in bacterial conjugation
Term
common pili
Definition
involved in cell adherence/attachment
Term
Pili in Neisseria
Definition

undergo phase and antigenic variation

tips may have lectins tha bind to specific sugars

Term
where is the antigenic variation found in Neisseria pili
Definition
variable C terminus
Term
What is the mechanism of antigenic variation
Definition
evades host immune system by changing surface proteins: pilin outer membrane proteins by gene conversion
Term
Flagella
Definition

organelles for locomotion

composed of 3 parts

composed of flagellin

has H antigen

used in id of Salmonella/Enterobacteriacea

undergo phase variation

Term
what are the three parts of flagella
Definition

basal body

hook

filament

Term
what is flagellin
Definition
helically coiled protein subunits
Term
what does flagella do and what is the energy for this action
Definition

propel cells by rotation motion

proton motive force

Term
what are flagella's four arrangements
Definition

monotrichous

lophotrichous

ampitrichous

peritrichous

Term
what two species of bacteria undergo the swarming phenomena
Definition

Proteas

Bacillus

Term
what is bacterial chemotaxis
Definition

process of moving in specific direction in response to environmental stimuli

swim counterclockwise toward an chemoattractant

swim clockwise away from repellents

Term
chemotaxis signaling pathway
Definition

terminates at flagella motor

starts with the binding of chemoattractancts/repellants to chemoreceptors in the membrane

either methylation or demethylation of methyl accepting chemotaxis proteins that triggers the rotation of flagellum and tumbling

Term
cytoplasmic inclusions
Definition

storage granules (metachromatic)

storage mechanism when nutrients are low

id feature in Corynebacterium diphtheriae

Term
different types of cytoplasmic inclusions
Definition

polymetaphosphates-volutin granules (babes ernst)

glycogen- like polymers

poly beta hydroxybutyric acid

Term
ribosomes
Definition

protein synthesis

70S= 50S +30S

60% RNA and 40% protein

30S subunit (16S RNA and 21 proteins)

50S subunit (23S RNA, 5S RNA and 34 proteins)

 

Term
Spores
Definition

found in gram-positive bacteria

are dormant and dehydrated

resistant to heat, chemicals, drying, freezing

contains chromosome, proteins, ribosomes, and high concentrations of calcium dipicolinic acid

Term
when are spores formed
Definition
in response to nutritional deprivation
Term
sporogenesis
Definition

spore mRNA transcribed

chromosome is duplicated

core is formed along with the cortex

protein coat is formed

exosporium is formed

 

Term
germination
Definition

conversion of spores to vegeatative cells

outgrowth

Term
what stimulates germination
Definition
disruption of outer coat: stress, pH, heat
Term
what does germination require
Definition
water, triggering nutrient (alanine)
Term
teichoic acid
Definition

rich in glycerol phosphate/ribitol phosphate

attached via phosphate groups to muramic acid in PG

found in gram positive bacteria

Term
teichoic acids function
Definition

activate alternative pathway of complement

adhesion of bacteria to host cells

involved in the antigencity of the cell wall

Term
what is lipoteichoic acid function
Definition
anchors wall to cell membrane and function as an epithelial cell adhesion
Term
outer membrane
Definition
covalently attached to PG through lipoprotein layer
Term
cell envelope-gram negative bacteria
Definition

reinforced cell shape

provided protection

excludes hydrophobic protein

an asymmetric bilayer

external layer composed of LPS

Term
what penetrates outer membrane slowly
Definition
antibiotics
Term
porins
Definition

outer membrane proteins

trimeric proteins

has a pore that allows chemicals and nutrients traverse the outer membrane along with hydrophilic solutes

Term
what are the three regions of LPS
Definition

lipid a

core polysaccharide

o antigen

Term
somatic o antigens
Definition

repeating carbohydrate units

attached to the core and extends away from the cell

distinguishes serotypes of a species

accounts for antigenic diversity among serotypes

if its missing there is sensitivity to bile salts and antibiotics

Term
core polysaccharide
Definition

has an outer (structural variability) and inner (low structural variability) core

has 2-keto-3-deoxyoctulosonis acid (KDO)

associated with serologic specificity

branched 9-12 sugars

Term
lipid a
Definition

responsible for toxicity of endotoxin  pyrogenic

consist of a chain of phosphorylated D-glucosamine disaccharide units with fatty acids attached

 

Term
Beta hydroxymyristic acid
Definition
most commonly observed lipid a in fatty acids
Term
synthesis of LPS
Definition

lipid a and core portion synthesized on inner surface of cytoplasmic membrane

repeat units of the O antigen are assembled on a bactoprenol molecule

finished o antigen chain transferred to core lipid a structure

Term
lipooligosaccharide (LOS)
Definition

present in Neisseria gonorrheae, N. meninigitidis

lacks o antigen portion of lps

readily shed from the bacteria

important virulence factor

Term
pathophysiology of LPS
Definition

stimulate innate immune responses

activates B cell and induces macrophages release cytokines (interleukin 1,6 and TNF)

complement and coagulation cascades are activated

fever and shock

DIC

death from massive organ dsyfunction

Term
lysozyme/penicillin
Definition

hydrolyzes the band between N acetyl glucosamine and N-acetylmuramic acid

treatment of gram positive bacteria produce protoplasts

"" of gram negactive bacteria produce spheroplasts

Term
mycoplasma
Definition

no cell wall

variable morphology

sterols in cytoplasmic membrane

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