Quiz 2 Flashcards by Rebekah Wielenga

What makes a cell gram-positive?

Thick peptidoglycan cell wall (~90%), and one cell membrane - not lipid rich

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Many gram positive cells have ________ acids attached to the cell wall.

teichoic

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Teichoic acids

polysaccharide derivatives of ribitol phosphate or glycerol phosphate linked via phosphodiester linkages: partially responsible for negative charge of the cell

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peptidoglycan composition

rigid layer of 2 sugar derivatives: N-acetylglucosamine and N-acetylmuramic acid, and some amino acids. Sugars bind to each other in chains in glycosidic linkages and cross-link with amino acids.

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gram negative

~10% peptidoglycan, with two membranes sandwiching it

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space in between the cell membranes of a gram negative bacteria is called

periplasm

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lipids are (soluble/insoluble) in alcohol

soluble

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how does the cell wall prevent decolorization

alcohol causes dehydration and the cell wall shrinks, trapping the crystal violet

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mordant in gram staining

iodine forms an insoluble compound with crystal violet in both types of cell walls

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Escherichia coli is gram ________

negative

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Staphylococcus epidermidis is gram _________

positive

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acid-fast staining detects the presence of

mycolic acid

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which genus has mycolic acid layer

Mycobacterium

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mycolic acid characteristics

binds to the peptidoglycan cell wall, creates a waxy/crusty layer, hydrophobic/resistant to dehydration, clump together when stained

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acid-fast primary stain and components

carbolfuchsin:
phenol: penetrate the waxy layer
basic fuchsin: lipid soluble, can enter waxy layer

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mordant for acid-fast staining

steam and heat

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decolorizer for acid-fast stain

acid-alcohol

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decolorizer for gram stain

alcohol

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color of acid fast and non acid fast bacteria

acid-fast: red due to carbolfuchsin
non-acid-fast: blue due to methylene blue

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examples of acid-fast bacteria

Mycobacterium tuberculosis, Mycobacterium leprae, Mycobacterium smegmatis

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Klebsiella pneumoniae characteristics

RG 2
Gram negative bacilli
Opportunistic pathogen
Associated with UTIs, blood infections, skin infections, etc
figure 8 shaped capsule

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capsules:

polysaccharide layer referred to as the glycocalyx
heat sensitive
water soluble
made of glycoproteins, polypeptides, and polysaccharides

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glycocalyx

polysaccharide containing material outside the cell

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capsules can

increase virulence (protect from phagocytosis)
prevent dehydration/desiccation
attach to host cells easily

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genera known to produce endospores

Bacillus and Clostridium

color of vegetative cell and endospore in spore stain

red/pink cell; green endospore

central, terminal, and subterminal

middle, end, middle-to-end

layers of a spore

exosporium, spore coat, cortex, core

Spore Core characteristics

dipicolinic acid and Ca+2 composes 10% of dry weight dehydrated, 10-25% water slightly acidic high levels of SASPs protect DNA and are important in germination

SASPs

small acid-soluble proteins

vegetative cell differences from spores:

low Ca+2 no dipicolinic acid 80-90% water

endospores are resistant to

heat drying UV radiation chemicals (dyes)

endospore resistance is due to

thick spore coat pH of the core(acidic) dehydrated nature

Bacillus anthracis spore effects

causes anthrax

Bacillus cereus spore effects

food poisoning

Clostridium tetani spore effects

tetanus

Clostridium perfringens spore effects

gas gangrene and food poisoning

Clostridium botulinum

causes botulism

Bacillus/Clostridium are anaerobic/aerobic

bacillus is aerobic clostridium is anaerobic

stains used is endospore stain

malachite green for endospores safranin as counter stain

what rotation direction causes flagella to bundle; "run"

counterclockwise

when the cell rotates clockwise,

it "tumbles"; turning or slowing

flagellin

the protein that flagella are made of

amphitrichous

flagella at both ends

peritrichous

flagella around perimeter

monotrichous

single flagella at one end

lophotrichous

tuft of flagella at one end

motility test medium contains TTC, which is

2,3,5-triphenyl tetrazolium chloride colorless and soluble when oxidized, red when reduced

semisolid media contains what percent agar

0.4-0.5%

solid media contains what percent agar

1.5%

flagella average length and diameter

10-20um length (up to 70um), 20nm diameter

good solidifying agents characteristics and examples

are not used by bacteria do not inhibit bacterial growth doesn't liquefy at room temp agar and silica gel

macronutrients vs micronutrients

needed in large amounts( C, N, P, S, K, Mg, Ca, Na) vs needed in small amounts (metals)

nutritional requirements in media

water, carbon, energy, nitrogen, minerals, growth factors, pH (H+)

autotrophs

utilize inorganic nitrogen, can use C in CO2 to synthesize materials

heterotrophs

must have organic compounds for C, can use organic or inorganic for energy, use amino acids and intermediate protein compounds for N

phototrophs

can use light as energy source

chemotrophs

can use chemicals for energy source

lithotrophs

use inorganic substances for energy (nitrate, nitrite, sulfate)

synthetic (defined) media

exact composition is known

non-synthetic (complex) media

exact chem. composition unknown

selective media

media that only allows certain organisms to grow

differential media

changes the appearance of a species to differentiate it from others

Eosin Methylene Blue (EMB) media

selective and differential methylene blue inhibits gram + eosin causes coliforms to turn green

minimal media

contains basic needs; salts, C, N

enriched media

basic needs plus amino acids, minerals and vitamins

methods of sterilization

autoclaving UV irradiation ethylene oxide gas

steam sterilization requirements for 1L media

15psi and 250F/121.6C

pure culture

contains only one type of organism

four streaking types

quadrant, t-streak, radiant, continuous

Escherichia coli characteristics

cream colored in environment and intestinal tract endotoxins can cause food poisoning, UTis, etc

Micrococcus luteus characteristics

yellow due to carotenoid pigments found everywhere, a common contaminant and indicates improper decontamination

Serratia marcescens

produces red pigment prodigiosin at 25-30C, white/cream at higher temp all over, biofilms nosocomial infection(infection from hospital)