Week 3 Quiz (staining lab)

Order the reagents used in the acid-fast staining procedure. Carbolfuchsin Methylene blue Acid-alcohol

1. Carbolfuchsin 2.Acid-alcohol 3.Methylene blue

Please order the following choices to reflect the appropriate sequence of materials used in the Gram staining procedure. Safranin Crystal violet Gram's Iodine Alcohol

1. Crystal violet - primary stain 2. Gram's Iodine - mordant 3. Alcohol - decolorizer 4. Safranin - counterstain

Order these statements to indicate correct aseptic procedure for removing organisms from a culture for application to a slide.

1. Heat inoculating loop and wire to red-hot. 2. Remove the cap of the culture tube and flame the mouth of the tube. 3. Remove a loopful of organisms from the culture. 4. Flame the mouth of the culture tube. 5. Return the cap to the culture tube. 6. Remove a loopful of organisms from the culture. 7. Flame the loop red-hot before setting aside.

Move the descriptions into the correct boxes to assess your understanding of the differences between endospores and vegetative cells. 1. Gram-negative organisms might incorrectly stain purple. 2. Gram-negative organisms might not be visible. 3. Gram-positive organisms might incorrectly stain pink. 4. You may not be able to view any organisms on the slide.

1. You forgot the decolorization step 2. You forgot to apply safranin 3. You forgot the crystal violet step / You applied the decolorizer for too long / you forgot the grams iodine 4. You did not heat fix the smear correctly

Please match the cell types with the statements that most accurately describe them to test your understanding of cell walls. 1. gram positive cells 2. gram negative cells 3.Acid-fast cells

1. cells which contain a thick peptidoglycan cell wall and also have teichoic acid 2. cells that have a thin cell wall with an inner and outer membrane, also containing a periplasmic space 3. cells which contain a thick layer of mycolic acid or cord factor

Move the descriptions into the correct boxes to assess your understanding of the differential staining techniques, including Gram stain, acid-fast stain, and spore stain. 1. Spore Stain 2. gram stain 3.acid-fast strain

1. uses malachite green, and distinguishes between active metabolic cells and dormant structures 2. differentiates cells based on thickness of peptidoglycan, result in purple or red cells, uses mordant as a chemical 3. does NOT require heat to be used in the staining process, differentiates cells with high lipid content in cell walls, important diagnostic tool in mycobacterium infections, and uses basic fuschin, acid alcohol, and methyl blue

Please select all of the statements that are true about endospores.

Bacterial endospores are highly resistant to heat, drying and radiation. Endospores can exist in the environment for indefinite periods of time. Endospores resist boiling and therefore steam must be used to destroy endospores present in food.

The Gram stain is an example of a _______ staining procedure, which takes advantage of the fact that cells or parts of cells react differently and can be distinguished by the use of two different dyes.

Differential

T/F It is important that the smear is thick in order to ensure that the stain will be retained on the slide.

FALSE

Why is negative staining useful for accurately determining cell size?

Heat fixation is not performed so cells do not shrink.

Please choose the answer that best completes the blanks of this sentence in the correct order. _______ is used to stain the endospore, and _______ is the stain used to stain the vegetative cell in spore staining.

Malachite green; safranin

What is heat fixation

Passing the slide through the flame of a burner several times after the smear has completely dried.

Select the statements that represent goals in correct smear preparation.

The cells must be heat-fixed to the slide to prevent removal when the stain is washed off the slide. It is important to minimize any artifacts or distortion of the cells for accurate viewing after staining. Smears must be thin to allow for observation of single cells.

You make a smear of E. coli and then simple stain the slide with methylene blue. If you failed to use correct aseptic technique by not sterilizing the loop before picking up the bacterial sample for the smear, what results may be seen under the microscope?

There may be cells of different shapes, sizes, and arrangements.

How does smear preparation of cells from a liquid medium differ from preparation of cells from a solid medium?

Water is applied to the slide before emulsifying cells from a solid medium.

Before heat fixation, a wet smear of bacterial cells on a slide must first be

air-dried

A _______ stain is one that colors the background surrounding the cell, leaving the cell itself unstained.

negative staining

Please choose the answer that best fills in the blanks of this sentence in the correct order. Gram-________ cells stain purple whereas gram-_______ cells stain pink or red when using the Gram stain technique.

positive; negative

Move the descriptions into the correct boxes to assess your understanding of the differences between endospores and vegetative cells. Vegetative cells Endospores

vegetative cells: stained with safranin, actively metabolizing, and high water content endospores: highly resistant to heat and chemicals, stain with malachite green, require autoclave for destruction. formed when conditions are unfavorable, and heat is the mordant to facilitate staining of these