Untitled Flashcards Set

Describe in order, the reagents used in the gram stain and state the purpose of each?

Crystal Violet - Used to stain organisms purple
Iodine - Used to fix stain
Alcohol-acetone - Used to wash away stain from gram-negative organisms
Safranin - Stains gram-negative organisms red

aerobic?

with oxygen

Anaerobic?

Without oxygen

Microaerophilic?

organisms that can tolerate or require environments containing levels of oxygen lower than that present in the atmosphere

Monotrichous?

Having only one flagellum

Atrichous?

Having no flagella

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Peritrichous?

Covered all over with uniformity distributed flagella

Amphitrichous?

Having a single flagellum at each end

Thermophilic?

heat loving organisms, with an optimum growth temperation of 50oC or more, a maximum of up to 70oC, and a minimum of about 20o C. They have been found in various geothermally heated regions of the Earth such as hot springs like those in Yellowstone National Park and deep sea hydrothermal vents

Mesophilic?

Organisms that grow in moderate temperatures ranges, from about 20o C (or lower) to 45oC. The habitats of these organisms include soil, the human body, animals, etc.

Psychrophilic?

Organisms that can grow at 0oC, and some even as low as -10oC; their upper limit is often about 25oC. They are present in alpine and arctic soils, high-latitude and deep ocean waters, arctic ice, glaciers, and snowfields

Neutophile?

grow best at neutral pH of 6.0-7.0, but mostly at 7.0

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Acidophile?

Any organism that grows best under acidic conditions (low pH)

Alkalophile?

Any organism that grows best under alkaline conditions

What is a halophilic organism? Give an example of where in nature this type of bacteria might grow

Extremophiles that thrive in environments with very high concentrations of salt. These are the primary inhabitants of salts lakes, inland seas and evaporating ponds of seawater, such as sea and solar salters

List the components of a bacterial cell?

Cell wall
Cell membrane
Chromosome
Nuclei
Cytoplasm
Plasmid
Pili
Ribosome
Flagella
Endospores

Cell wall?

-gives bacteria its shape
-site of action for many antibiotics
-determines gram reaction

Cell membrane?

-inside cell wall
-thin permeable membrane of lipids
-protein embedded in it
-regulates exchange of materials into and out of the cell

Chromosome?

closed circle of double stranded DNA which contains the genetic info. Of the cell

Nuclei?

area in the cytoplasm where the chromosome is located

Cytoplasm?

liquid matrix of the cell, made mostly of water, dissolved nutrients and wastes

Plasmid?

small piece of extra chromosomal DNA. It is much smaller than the Chromosome, and is double stranded. It may be transferred from one cell to another

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Pili?

hair-like structure extending from the surface of the cell for attachment to other cells(human/bacteria) or to other surfaces to exchange plasmids: sex pili used in process called conjugation

Ribosomes?

site of protein synthesis bacteria. Humans have 80s ribosome's (40s+60s)

Flagella?

responsible for bacteria motility polar or monotrichous-one flagella at one pole tuft or
ophotrichos- group of flagella at one pole peritrichous- flagella over entire surface of bacteria
amphitrichous- single or tuft at one or both poles
atrichous- w/o flagella

Endospores?

some bacteria have them, some don't. They are a resistant form of microorganism and form when environmental conditions are unfavorable. E.g.: Clostridium botulinum

What is the pressure, temperature, and time for autoclaving media?

15 LB above atmospheric pressure(psi), 121C, 15 minutes

List two purposes of heat fixing prior to staining a smear.

To make bacteria adhere to the slide and to prevent the bacterial cells from washing off the slide in subsequent staining operations

List three bacterial morphologies and describe their shape.

cocci-sperical or round bacteria
Bacilli- straight rod-shaped
Spirilla- spiral-rod shaped

antiseptic?

chemical used to control the growth of microorganisms on living tissues

Disinfectant?

chemical used to kill or control the growth of microorganisms

Bacteriocidal?

100% killing of microbes

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Bacteriostasis?

reduces growth

Sterillization?

100% killing of microbes in or on a surface

What substances or features does SIM's media test for?

Motility, H2S, and Indole production

What biochemical test is used to differentiate Staphylococci from Streptococci?

The catalase test is used to differentiate Streptococci from Staphylococci

What biochemical test is used to differentiate Pseudomonas from Enterobacteriacea?

The Biochemical test OxidaseProduction is used to differentiate Pseudomonas from Enterobacteriacea

What is the coagulase?
What organism is positive for the test?

The coagulate test is when in the presence of the enzyme coagulase, rabbit plasma will form a fibrin clot which is visible to the naked eye. Coagulase can form a bound to the cell wall of S. aureus and be detected by a slide test; free coagulase can be detected by a tube test. Staphylococcus aureus will be positive.

What are the two-petri plates that you can use to determine lactose fermentation?
Describe the color of lactose positive and a lactose negative organism on each type of plate.

In MacConkey Agar lactose fermenters are hot pink to red and non-lactose fermenters are colorless or very light pink colonies. Hektoen Enteric Agar shows lactose fermenters as yellow and non-lactose fermenters as green colonies

Which organism is positive for Bacitracin?
What illness does this organism causes?

A beta-hemolytic streptococcus for group A is a positive for Bacitracin. This organism causes streptococcal pharyngitis.

What organism is positive for Optochin?
What illness does this organism cause?

Streptococcus Pneumoniae is positive in an Optochin test. It can cause sinus in the ear and even lead to pneumonia or meningitis.

How does an increase in incubation temperature affect microbial growth?

The increase in temp would inhibit or slow the growth of all but the thermophiles

How does a decrease in incubation temperature affect microbial growth?

Decreasing the temp causes the psychrophiles to grow better.

Why are petri plates inverted prior to incubation?

To prevent the condensation from dropping down on to the inoculated media.

What substances does the indole test detect?
What reagents are used?

It test for bacteria that have the enzyme tryptophanase it uses Kovac's reagent

What do the initials MR stand for?

MR-Methyl Red

What substance does the MR test for?

test for bacteria that produce pH of 4.4 or less

What do the initials VP stand for?

VP -Vogues Prokauer

What substance does the VP test for?

tests ability to produce acetylmethyl carboninol

What reagents are used for VP?

uses Alpha napthol and Potassium Hyroxide

Which power of the microscope does one use to observe the gram stain and morphology?

100 X Oil submersion

Name six common bacterial arrangements

-Singles
-pairs
-clusters
-chains
-diplococci
-tetrads

What will the bacteria look like if the gram stain is completed, but the decolorizer is left on too long?

lose purple stain and end up staining red

What is the basic premise behind streak plating?

to let bacteria form a colony from a single organism

What is the purpose of streak plating?

to get good isolation of microorganism

List the three basic forms of media.

-liquid
-solid
-semi-solid

Differential media?

media that allows growth of groups of organisms and demonstrates certain characteristics. most differential media is also selective

Selective media?

media that contains chemicals or dyes that prevent or retard growth of certain organisms and select or allow growth of other organisms without necessarily differentiating them

Benrichment media?

basic media containing additives such as blood or serum which enhance the growth of many fastidious and non-fastidious organisms

What is a pure culture?

culture in which each colony is from a single isolated original bacterial cell

What is a mixed culture?

culture in which each colony contains many species

Pseudomonas aeruginosa?

causes respiratory & urogenital infections

Streptococcus pneumoniae?

causes pneumonia

Staphylococcus aureus?

causes boils, carbuncles, pneumonia, and septicemia

Escherichia coli?

causes urinary infections

Salmonella enteritis?

causes typhoid fever

Neisseria gonorrhea?

causes gonorrhea

Klebsiella pneumoniae?

causes pneumonia

Clostridium botulinum?

causes botulism