staining lab

in the capsular stain, what does the counterstain dye

the cytoplasm

place the steps of the endospore stain in the correct sequence

1. apply malachite green to smear 2. cover smear with small piece of paper towel 3. steam over water bath 4. rinse 5. apply safranin to smear 6. rinse and blot dry

place these reagents in the proper order of their use in the gram staining technique

1. crystal violet 2. gram's iodine 3. decolorizer 4. safranin

put the following steps in order for performing a smear preparation from a liquid culture

1. label the microscope slide 2. apply loopful of bacterial culture to slide 3. air dry 4. heat fix

why might it be important to perform a gram stain on bacterial cells

as part of the information used to choose an appropriate antibiotic treatment

put the following steps in order for performing a smear preparation from a solid culture

1. label the slide with the name of the organism 2. apply loopful of sterile water to slide 3. add very small amount of organisms to water on slide 4. disperse organisms evenly over the center of the slide 5. air dry 6. heat fix

place the following steps of the capsular stain in the proper sequence

1. place a drop of nigrosin on a clean slide 2. add bacteria to nigrosin and mix 3. spread the mixture over slide and air dry 4. apply crystal violet 5. rinse

match the general type of staining method with its description

1. simple : uses only a single dye to color the cells 2. differential stain : uses two dyes to discriminate between cell types or structures 3. structural stain : assists in the observation of structures external to the cell wall

place the following steps of the acid-fast stain in the proper sequence

1. stain with carbolfuchsin 2. rinse off excess primary stain 3. decolorize with acid alcohol 4. rinse with water to stop the decolorization process 5. counterstain with methylene blue 6. rinse off excess counterstain 7. bolt dry

which of the following can be determined by observing bacteria that have been stained through a light microscope

cellular arrangement, cellular morphology

staining can be used to identify which of the following

cellular structures, cellular arrangement, cell shape

if carbolfuchsin was omitted from the acid-fast stain, what color would acid-fast cells appear

clear

if malachite green was omitted from the endospore stain, the endospores would appear ___ in color

clear

if safranin was omitted from the endospore stain, the vegetative cells would appear ___ in color

clear (colorless)

what outcome could be expected if you forgot the crystal violet step while performing a gram stain

gram positive and gram negative organisms would stain pink

if you forget to use the decolorizer, which cell types will appear purple

gram positive and negative

if safranin was omitted from the endospore stain, what color would the endospores appear

green

in this image, the endospores are ___ in color

green

in order to ensure that dye penetrates the spore coat and stains the endospore, which of the following is needed

heat

when should heat fixation take place during the capsular stain

heat fixation is not required in the capsular stain

which of the following describes the correct sequence of the gram stain procedure

heat-fixed slide; use of crystal violet, iodine, decolorizer, and safranin

which of the following is true regarding proper heat fixation

heating too briefly may result in bacteria not adhering to the slide

which of the following is a significant lipid component of the cell walls of acid-fast bacteria

mycolic acid

gram-___ cell walls contain a thin layer of peptidoglycan whereas gram-___ cell walls contain a thick layer of peptidoglycan

negative, positive

this slide depicts a mixed culture of bacteria that were properly stained using the acid-fast stain. which are more numerous, acid-fast or non-acid-fast cells

non-acid-fast

this slide depicts bacteria that were properly stained using the acid-fast staining technique. the bacteria appear to be ___

non-acid-fast

which of the images depicts a slide that has been properly stained using a simple stain procedure

D

which of the following are functions of the bacterial capsule

adherence, protection

based on their cellular morphology, the red cells on this slide would be referred to as

bacilli

which of the following bacteria genera are capable of producing endospores

bacillus, clostridium

in a negative stain, which of the following is stained

background

which of the following stains do not require heat fixation

capsule stain

if methylene blue was omitted from the acid-fast stain, non-acid-fast cells would be ___ at the end of the staining process

clear

the capsule staining technique begins with a ___ stain

negative

what is used as the mordant in the gram staining technique

gram's iodine

if malachite green was omitted from the endospore stain, vegetative cells would appear ___ in color

pink

if you decolorize for more than 30 seconds, gram positive organisms will most likely appear ___ in color

pink

in this image, the figure on the left represents a gram ___ cell wall whereas the figure on the right represents a gram ___ cell wall

positive; negative

the name of the counterstain, or secondary stain, typically used in gram stain technique is

safranin

in a differential staining technique, the stain that is used after the decolorization step is called the counterstain, or ___ stain

secondary

which of the following provides a quick and effective method used to visualize and determine bacterial morphology and arrangement

simple stain

to prepare a ___, a sample of bacteria is taken from a culture and spread onto a clean microscope slide

smear

which occurs first in the endospore stain

staining of the endospore

the organism in the slide exhibit a cellular arrangement known as

staphylococcus

spherical cells arranged in a chain are called

streptococci

the morphology and arrangement of the organism represented in the image would be characteristic of the genus

streptococcus

what is stained by the initial dye in the capsular stain procedure

the background

you have just performed an acid-fast stain, and all of the cells appear to be blue. which of the following could explain your results

the bacteria are non-acid-fast

why is heat fixation not part of the protocol for the capsule stain

the capsule may be damaged

which of the following descriptions reflects observations of a capsular stain that may have been heat fixed

the capsules cannot be seen clearly on the slide

which of the following structures makes it difficult to stain endospores

the endospore coat

what could happen if heat fixation was performed prior to doing a capsular stain

the heat might alter the morphology of the bacteria

which of the following describes the correct method for heat fixation

the heating should be very brief . passing the slide through the flame for 3-5 seconds is enough

this image shows the results of an endospore stain performed on an endospore-producing strain of bacteria. identify which step in the endospore stain was omitted in order to get the results depicted in this slide

the primary stain, malachite green was not used

you are observing klebsiella pneumoniae on a slide that has been stained using the capsular staining method; however, you do not see capsules surrounding the cells as you expected. what is the likely reason for this

the slide was heat fixed

which of the following apply to endospores

they are used for surviving adverse environmental conditions

why is it important to air dry the bacteria before they are immobilized by heat fixation

this ensures the optimal preservation of the bacterial morphology

what is the purpose of the smear preparation

to allow for visualization of individual bacteria

what is the purpose of the gram staining technique

to characterize unknown bacteria

which of the following represent consequences of incorrect performance of the decolorization step

- decolorizing too briefly: false positive results - decolorizing for too long: false negative results - decolorizing for too long: removal of carbolfuchsin (primary stain) from all cells

endospores are difficult to stain due to which of the following

- endospores exclude dye - endospores have a thick spore coat

which of the following correctly describe how the gram stain works to color different type of cells

- gram positive cells retain the purple dye mordant complex because of their thick layer of peptidoglycan - gram negative cells are decolorized and stained by the pink/red secondary stain

if organism are washing off of the slide during rinsing of the stain, which step(s) in the smear preparation may have been excluded

- heat fixation - air drying

before bacteria from a solid culture are applied to a slide, a drop of sterile water is typically added to the slide in order to

- help the bacteria spread evenly - reduce the tendency of the bacteria to stick together

a smear preparation that is too light may result in which of the following

- inability to distinguish individual cell morphology - difficulty locating cells to observe

a smear that is too thick will result in which of the following

- inability to distinguish individual cell morphology - poor quality stain results

which of the following are diseases caused by an acid-fast bacterium

- leprosy - TB (tuberculosis)

which of the following clinically important organisms are considered acid-fast

- mycobacterium tuberculosis - mycobacterium leprae

which of the following would lead to an inability to identify the morphology of organisms using a simple stain

- no organisms in sample - the organism has an acid-fast cell wall - more than one organism in your sample

what might be the result of not allowing a slide to air dry sufficiently prior to heat fixation

- the shape and arrangement of the cells may be disrupted - the bacteria may rinse off of the slide - the bacteria could be aerosolized

which of the following would be appropriate for choosing a sample to perform a smear preparation

- use only a small amount of bacteria on the loop - use bacteria from an isolated colony

which of the following are characteristics of simple stains

- used to visualize morphology of bacteria - used to identify cellular arrangement of bacteria

how do you smear a bacterial colony onto the microscope slide

- using the loop, you disperse the bacteria into the water drop on the microscope slide

staining is a commonly used microbiological technique that is used for which of the following

- visualization of microorganisms - differentiation of microorganisms - identification of some bacterial structures

you just performed an acid-fast stain on an acid-fast organism, yet some of the bacteria appear blue and some appear red. which of the following could explain your results

- you have a mixed population of bacteria in which some organisms are acid-fast and some are not - the primary stain was not allowed to stain long enough

which would be the proper amount of time required for methylene blue dye to remain on the bacterial smear during a simple stain

30 seconds to 2 minutes

which of the images shows a simple stained slide that was prepared from the appropriate amount of microbial material

C

in the kinyoun acid-fast staining method, highly concentrated ___ is used to penetrate the cell wall and colorize acid-fast bacterial cells

carbolfuchsin

which of the following could be determined through simple staining of a microbial smear

cell morphology, cellular arrangement

which of the following are terms used to describe the colored dyes applied in the gram staining technique

counterstain, primary stain

what is the primary dye used to the gram staining technique

crystal violet

in a differential staining technique, a ___ is used to remove the primary stain from the bacterial cell

decolorizer

in order to withstand hostile conditions and facilitate survival, some bacteria produce resistant structures known as ___

endospores

omitting the steaming in an endospore stain would result in which of the following

endospores would not take up stain

the simple stain provides enough information about microbe to clearly identify its species

false

if decolorization was omitted from the acid-fast stain, what color would non acid-fast cells appear

pink/red

if methylene blue was omitted from the acid-fast stain, what color would acid-fast cells appear

pink/red

if decolorization was omitted from the acid-fast stain, what color would acid-fast cells appear

red

what is the most likely reason for the poor appearance of the bacteria on this slide

the slide was heat fixed for too long

what is thought to cause gram positive cells to retain the primary stain and the mordant complex whereas gram negative cells are decolorized

the thickness of the peptidoglycan layer

stains are commonly used for all the following except

the treatment of disease

this image likely depicts a gram stained slide

true

two clinically significant genera of bacteria that are capable of producing endospores are clostridium and bacillus

true

how do you smear a bacterial culture onto the microscope glass slide

using the loop, you spread the bacteria onto the center of the microscope slide

bacterial cells that are curved rods or comma-shaped are called ___ whereas helical bacteria are referred to as spirilla or spirochetes

vibrio

there are many types of staining techniques used in microbiology. which of the following is not a commonly used staining technique

wright's stain

___ is used to stain the vegetative cells in the endospore staining procedure

safranin

which of the following is/are the most appropriate way to correctly label the name of an organism on a glass slide

- E. coli

the purpose of heat fixation is to

- adhere the organisms to the slide - inactivate microorganisms placed on the slide

excessive heating during the fixation stage of preparing a smear can lead to which of the following outcomes upon staining

- bacterial cells may show altered morphology - bacterial arrangements may be disturbed

which of the following apply to bacterial smears

- bacterial smears provide scientists with the means to look at microorganisms - preparing smears disperses bacterial cells on a slide so that individual cells can be visualized under the microscope - preparation of bacterial smears is required for bacterial staining procedures

match the staining procedure with its description

- capsule stain : a stain that enables you to effectively visualize a bacterium's glycocalyx - gram stain : a stain that can differentiate between cells that have thick or thin layers of peptidoglycan in their cell walls - acid fast stain : a stain that would be appropriate for cells that contain mycolic acid in their cell walls

which three of the following terms all refer to a similar structure

- glycocalyx - slime layer - capsule

which of the following stains required heat fixation

- simple stain - endospore stain - gram stain - acid-fast stain

encapsulated organisms are difficult to directly stain because

- the capsule is not permeable to stains - the capsule does not react with most stains

what is the purpose of a simple stain

- to determine cell shape and arrangement of the specimen - to visualize bacteria

what is the purpose of a negative stain

- to determine morphological characteristics of the specimen - to visualize a capsule (if present) - to visualize the bacteria

this image depicts the results of an endospre stain performed on a smear of a known endospore-producing bacterial species. which of the following could have led to the results shown here

- too many organisms were used - the primary stain was omitted - the smear was performed from a young culture that was not yet forming endospores

which of the images depict a slide that was prepared from an excessive amount of microbial material

A

which slide shows both vegetative cells and endospores

A

which of the images depicts a slide that has not been properly heat fixed

B

which of the images represents bacilli

B

heat fixation should take place right after which step in a smear preparation

air drying of smeared bacterial cells

which of the following is not a common staining method used for visualization of bacteria

all of the above are commonly used

bacterial cells that are rod-shaped are called

bacillus

which of the following is stained during the first part of the capsule staining procedure

background of the slide

if carbolfuchsin was omitted from the acid-fast stain, what color would non-acid-fast cells appear

blue

which of the following illustrates a properly stained capsular stain

c

excessive heat fixation can cause damage to which of the following structures, lowering the quality of the stained preparation

capsule, cell wall, cell membrane

___ is the initial stain used in the acid-fast stain

carbolfuchsin

based on the image, what step of the capsular stain was omitted

crystal violet

which stain is used to stain the cytoplasm of the cells in the capsule stain

crystal violet

the type of stain designed to show differences between various organisms or cellular structures if referred to as a ___ stain, whereas a ___ stain uses only one dye to stain all cell types

differential, simple

the ___ stain provides critical information about the peptidoglycan structure of the cell wall

gram

what might happen if you omitted the safranin step while performing the gram stain on a mixed culture of gram positive and gram negative cells

gram negative organisms might not be visible

which stain is used to stain the background in the capsule stain

india ink or nigrosin

___ ___ is used to stain the endospore in the endospore staining procedure

malachite green

the counterstain used in the acid-fast stain is ___ ___

methylene blue

the first dye applied in a differential staining technique is referred to as the ___ stain

primary

if you omit the gram's iodine step while performing the gram stain, gram positive cells will most likely be ___ in color

red

gram negative cells appear ___ after gram staining whereas gram positive cells appear ___

red; purple

staining techniques do not provide information on which of the following structures

ribosomes, cell membrane

staining allows for the visualization of bacterial cells because it increases contrast during microscopic imaging

true

a capsule stain was performed, using crystal violet as a primary stain, followed by a water rinse and then nigrosin as a counterstain. as you observe the slide through the microscope, you suspect you made an error. which of the following is the most likely problem with your technique

you should have started with nigrosin as the primary stain and used crystal violet as a counterstain