Microbio Lab 2 Exam

Ubiquitous

Ubiquitous

means found everywhere

pathogen(ic)

an agent (usually a virus, bacterium, fungus protozoan, or helminth) that causes disease

culture

the visible accumulation of microorganisms in or on a nutrient medium. Also the propagation of microorganisms w/ various media.

turbid

cloudy appearance of nutrient solution in a liquid test tube due to growth of microbe population

colony

a macroscopic cluster of cells appearing on a solid media like a petri dish, each arising from the multiplication of a single cell

3 rules to disern microbial growth on solid media

~you will usually have more bacterial colonies than fungal colonies

~bacterial colonies are usually smaller than fungal colonies

~fungal colonies usually look dry and cottony while bacterial look wet and shiny

bacterial cells and fungal spores may be found in…

food and drink

indoor air

outdoor air

microbes that are capable of causing disease are referred to as…

pathogens

laboratory disinfection is generally more stringent than hospital disinfection

true

When it said that microbes are ubiquitous, it means that…

microbes are found virtually everywhere

a tube containing growth media with microbes growing w/in is a…

culture

a visible mount of bacteria growing on a Petri dish and containing many thousands of cells all descended from a single cell is a…

colony

on a petri dish containing both bacterial and fungal colonies, the bacterial colonies would typically be…

smaller and wet in appearance

on the same petri dish, you would generally expect ______ colonies to be greater in number

bacterial

bacterial growth w/in a liquid medium can be recognized because the medium will be…

turbid

a visible bacterial colony growing on a plate generally contains hundreds of cells

true

pure culture

a container growing a single species of microbe whose identity is known

microorganisms are commonly found in soil, surfaces, and dust, but not on living surfaces like skin

false

microbes are generally…

~found everywhere

~invisible to the naked eye

when a sample is heavily populated w/ microbes, the microbes are generally visible to the naked eye

false

laboratory techniques that exclude unwanted microbes are called…

aseptic

isolation techniques are necessary in the microbiology lab because…

microbes are usually found as part of a mixed population

a tube of nutrient agar, upon which is growing a single species of bacteria is said to be a ___ culture

pure

a mound of hundreds of thousands of bacterial cells growing on a plate of agar, all descended from the same original cell is a …

colony

a loop is used to remove bacterial growth from a liquid culture and a needle is used to remove growth from a solid culture like a slant or plate

true

morphology

the study of organic structure

cocci (coccus)

a spherical shaped bacterial cell

bacilli (bacillus)

a cylindrical shaped bacterial cell

spirilla (spirillum)

a genus of spiral shaped bacteri a

pleomorphic (pleomorphism)

normal variability of cell shapes in a single species

diplococcus (diplococci)

spherical or oval shaped bacteria found in pairs

streptococcal

many cocci in a chain

tetrad

cocci in groups of four

sarcina

A cubical packet of 8, 16, or more cells; the cellular arrangement of the genus Sarcina in the family Micrococcaceae

staphylococcal

they appear spherical, and form in grape-like clusters

diplobacilli

rod-shaped cells found in pairs

streptobacilli

bacilli in a chain

palisades

the characteristic arrangement of Corynebacterium cells resembling a row of fence posts and created by snapping

chromophore

the color-bearing portion of a stain molecule

contrast

the degree of difference between the lightest and darkest parts of an image

negative staining

a staining technique that renders the background opaque or colored and leaves the object unstained so that it is outlined as a colorless area

simple staining

type of positive staining technique that uses a single dye to add color to cells so that they are easier to see. This technique tends to color all cells the same color

nigrosin and india ink

dyes or inks used in negative staining

methylene blue, crystal vio- let, malachite green, and safranin

dyes or inks used in positive staining

differential stain

allows the discrimination of one cell from another based on differential-staining properties

gram stain

this technique separates bacteria into two groups, Gram positive and Gram negative, based on differences in the structure of the cell wall

primary stain

the first stain used in a differential staining technique

mordant

a chemical that serves to fix a dye in a staining process

counterstain

an ink added to increase the contrast of the colorless Gram-negative cells, rendering them pink

gram positive

those cells staining purple

gram negative

those cells staining pink

a coccus that divides along two planes of symmetry would produce…

tetrad

the primary point of staining bacterial cells is to increase the contrast between the cells and the background

true

a staining technique that results in light organisms against a darkened background is a…

negative stain

which staining technique would provide the most accurate size of a bacterial cell

all staining techniques would give equivalent results

when preparing a bacterial smear growing on a Petri dish for staining you would…

use a needle to transfer a small amount of growth to a loop of water on the slide.

if you correctly stain a mixture of Gram-positive rods and Gram-positive cocci, you would expect to see…

purple rods and purple cocci

endospore

structural stain

staining method used to highlight a specific structure in the cell

endospores are produces by bacteria in the genera…

bacillus and clostridium

endospores are usually formed in response to…

a lack of carbon and nitrogen in the environment

in a properly done endospore stain, the endospore will appear the color…

green

the dye used in the first step of an endospore stain is…

malachite green

an endospore stain is an example of a…

structural stain

3 bacterial pathogens that form endospores and ds. associated with each

~Bacillus anthracis: anthrax

~Clostridium tetani: lockjaw, tetanus

~Clostridium botulinum: paralysis muscles, food poisoning

mycolic acid

A compound found in the cell walls of acid-fast bacteria

what genus contains acid fast bacteria

mycobacterium

what component of the cell wall is responsible for the manner in which acid fast bacteria absorb and release stain

mycolic acid

in a properly done acid fast stain. non acid fast bacteria will appear the color…

purple

the disease caused by members of the genus mycobacterium is

leprosy

an acid fast stain is an example of a

differential stain

differential stain

allows the discrimina- tion of one cell from another

motile

moving bacteria

chemotaxis

a complex movement of the cell toward nutrients or away from harmful substances.

wet mount

a procedure in which a small amount of a liq- uid culture is placed on a microscope slide and covered with a cover slip. The slide is then examined, and any rapidly swimming cells noted. Although quick and straightforward, wet mounts suf- fer from several problems, including a tendency to dry out, cur- rent movements that may mimic motility, and the potential for contamination of instruments and self with pathogenic microbes

hanging drop

technique, eliminates most problems with drying and water currents and reduces the chances of contamination. In this method, a cover glass is prepared with a small dab of petroleum jelly (Vaseline) on each corner and a single loopful of a liquid culture in the center. A special slide with a depression in the middle is then placed over the cover glass with the concavity in the slide centered over the drop. The petroleum jelly causes the cover slip to adhere to the slide as it is inverted. Revealing motile cells present.

brownian motion

The passive, erratic, nondirectional motion exhibited by microscopic particles. The jostling comes from being randomly bumped by submicroscopic particles, usually water molecules, in which the visible particles are suspended.

approximately what percentage of bacterial species are motile

50%

motility is usually determined by examining a gram stain for the presence of bacterial flagella

false

a wet mount is generally preferred to a hangaing drop to determine motility

false

brownian motion is

not a form of true motility regardless of cell type

both wet mounts and hanging drop slides should be allowed to sit for 30–60 minutes prior to being examined to allow the bacteria to recover from the transfer process and begin to display motility

false

motility medium is a

semisolid medium

Motility medium is solidified with gelatin to allow motile bacteria freedom of movement.

false

Motility medium is inoculated with a single loop of bacteria

false

A motility medium that appears cloudy after incubation would indicate that the bacterium in question is

motile

if, after incubation, a bacterium has grown along the stab line within the medium but has also spread across the surface of the medium, it should be classified as

motile

complex media

medium contains one or more ingredients that are not precisely known, often an extract of animals, plants, or yeast. Most media commonly used in the microbiology laboratory fall into this category with trypticase soy agar and nutrient broth being examples

defined media

media have a precisely known chemical composition, with each ingredient weighed and added to the media during preparation. Minimal agar serves as an example of this type of media

heterotrophs

bacteria that obtain carbon from organic compounds such as carbohydrates and proteins

autotrophs

a bacterium able to use carbon dioxide as its sole source of carbon

chemo

prefix that indicates that energy is derived through the breakdown of chemical substrates

photo

prefix that indicates that light is used to provide energy through photosynthesis

chemoorganotrophs

derive energy from the breaksown of organic molecules by fermentation or respirations

chemolithotrophs

rely on the inorganic ions as an energy source, oxidizing inorganic substrates such as iron to obtain energy

photoautotrophs

use photosynthetic pigments to convert sunlight into chemical energy through the process of photosynthesis

photoheterotrophs

use sunlight as a source of energy but carbon is obtained from the breakdown of organic molecules such as glutamate

nitrogen fixation

a process in which a small number of bacteria are even capable of using atmospheric nitrogen (N2)

growth factors

are complex organic compounds that are required for the growth of some fastidious organisms usually blood or serum

enriched media

when blood or serum are added to complete media to ensure the growth of certain bacteria on the medium