UAMS MICROBIOLOGY EXAM 1
STUDY GUIDE COMPLETE
QUESTIONS
◉ Specimen collection. It is a tube closed on the bottom and open at
the top with swabs inserted into the culturette container. Answer:
What is a culturette used for?
◉ Collect the specimen with a culturette tube, plate it using either
an agar or broth medium, incubate the culture, and then ID.
Determine antimicrobial susceptibility and report results. Answer:
What is the complete procedure done by the lab for collecting and
then identifying an organism?
◉ Coccus, coccobacillus, vibrio, bacillus, spirillum, and spirochete.
Answer: What are the different morphologies of bacteria?
◉ Coccus (one single colony), diplococci (two colonies),
staphylococci (multiple colonies in a triangle shape), streptococci
(multiple colonies in a linear row), sarcina (multiple colonies that
can be on top of one another in a square shape), and tetrad (four
colonies in a square). Answer: What are the different bacterial
arrangements for cocci?
,◉ Rod shaped. The genus (Bacillus anthracis). Single bacillus,
diplobacilli, streptobacilli, and palisade (rods laid side by side,
forming a fence-like appearance; can also be V-shaped). Answer:
What does bacillus or bacilli refer to? What about Bacillus? What are
the bacilli arrangements?
◉ Bacteria that is capable of altering its morphology to take on
many different shapes. Answer: What does the term pleomorphic
refer to? Ex. Pleomorphic bacilli
◉ Spores are cells with very thick walls that can survive many
extremes, allowing a bacterium protection in order to preserve its
genetic material. Answer: What are spores and what do they allow a
bacterium, such as bacilli with spores?
◉ Filamentous and fusiform. Answer: What are the two different
forms of bacilli rods?
◉ Hans Christian Gram. Crystal violet, iodine, decolorizer, and
safranin. The cell wall structure of the bacteria is what determines if
it is gram pos or neg. The thick peptidoglycan layer on gram pos MOs
retains the crystal violet-iodine complex. On gram neg MOs, there is
only a thin layer of peptidoglycan under a layer of lipids. The lipid
layer retains the stain and the decolorizer then dissolves the lipid
layer, removing the crystal violet-iodine complex. Answer: Who
invented the Gram stain and staining method? What are the reagents
,involved? How is Gram stain able to work? What makes some
bacteria gram pos and others neg?
◉ Safranin. Once the decolorizer dissolves the lipid layer holding the
crystal violet-iodine complex, the safranin is able to stain the thin
peptidoglycan layer underneath, causing the bacteria to appear pink.
The pink bacteria can then be identified as Gram neg. Answer: What
is the counter stain that is used alongside Gram stain to identify the
Gram neg bacteria? How does this work?
◉ Cells from a culture are taken and spread over a thin area of a
slide and then heat fixed. The smear doesn't need to be too thin or
too thick, otherwise it will be unable to be read properly. Smears are
heat fixed using a bunsen burner, an electric incinerator, or
methanol. This is done to kill the bacteria on the slide, prevent
bacteria from washing off the slide, and allowing the smear to take
up stain better. Answer: What is smear? What is important when
preparing a smear? How are smears heat fixed and why?
◉ Place the slide on a staining rack and cover the smear with crystal
violet solution. Let stand for 30-60 seconds. Rinse with tap water to
remove the crystal violet, then shake off excess water. Cover the
smear with Gram's iodine and let stand for 30-60 seconds. Rinse
with water, then shale off excess. Decolorize the smear with acetone-
alcohol and rinse with water as soon as the purple/blue color no
longer runs off the slide. *Be careful to not over or under decolorize*
Shake off excess water and counterstain with safranin for 30
, seconds, rinse with water, and dry slide by air or by blotting.
Answer: What is the Gram staining procedure?
◉ Gram neg cells such as human cells will appear washed out and
gram pos bacteria will appear gram neg or partially stained. Gram
neg cells such as human cells will appear dark red / purple and
other gram neg bacteria appear gram pos. Answer: What will
happen is the decolorizer is left on too long? What about under-
decolorized?
◉ Damaged cells are a potential problem when looking at older
culture, they will not take up stain. This can be due to antibiotics.
Overheating a slide distorts cells from their normal shape, causing
them to look weird when viewing. Improper reagent use can be a
source of error when one is omitted or they are used in the wrong
order. Excessive rinsing can wash out the crystal violet or crystal
violent iodine complex away, Prolonged counterstaining might cause
the crystal violet complex to be leached from the Gram pos MOs.
Answer: How will damaged cells pose as a source of error when
staining? How does overheating a slide pose as a source of error?
What about improper reagent use? What about excessive rinsing
and prolonged counterstaining?
◉ Media is used to culture specimens, isolate bacteria, biochemicals
used for identification, and used for antibiotic susceptibility.
Liquid broth, semi-solid agar (0.3-0.5%), agar slants, and solid agar
(1-2%). Polysaccharide is the main component, melting at 100 C and
STUDY GUIDE COMPLETE
QUESTIONS
◉ Specimen collection. It is a tube closed on the bottom and open at
the top with swabs inserted into the culturette container. Answer:
What is a culturette used for?
◉ Collect the specimen with a culturette tube, plate it using either
an agar or broth medium, incubate the culture, and then ID.
Determine antimicrobial susceptibility and report results. Answer:
What is the complete procedure done by the lab for collecting and
then identifying an organism?
◉ Coccus, coccobacillus, vibrio, bacillus, spirillum, and spirochete.
Answer: What are the different morphologies of bacteria?
◉ Coccus (one single colony), diplococci (two colonies),
staphylococci (multiple colonies in a triangle shape), streptococci
(multiple colonies in a linear row), sarcina (multiple colonies that
can be on top of one another in a square shape), and tetrad (four
colonies in a square). Answer: What are the different bacterial
arrangements for cocci?
,◉ Rod shaped. The genus (Bacillus anthracis). Single bacillus,
diplobacilli, streptobacilli, and palisade (rods laid side by side,
forming a fence-like appearance; can also be V-shaped). Answer:
What does bacillus or bacilli refer to? What about Bacillus? What are
the bacilli arrangements?
◉ Bacteria that is capable of altering its morphology to take on
many different shapes. Answer: What does the term pleomorphic
refer to? Ex. Pleomorphic bacilli
◉ Spores are cells with very thick walls that can survive many
extremes, allowing a bacterium protection in order to preserve its
genetic material. Answer: What are spores and what do they allow a
bacterium, such as bacilli with spores?
◉ Filamentous and fusiform. Answer: What are the two different
forms of bacilli rods?
◉ Hans Christian Gram. Crystal violet, iodine, decolorizer, and
safranin. The cell wall structure of the bacteria is what determines if
it is gram pos or neg. The thick peptidoglycan layer on gram pos MOs
retains the crystal violet-iodine complex. On gram neg MOs, there is
only a thin layer of peptidoglycan under a layer of lipids. The lipid
layer retains the stain and the decolorizer then dissolves the lipid
layer, removing the crystal violet-iodine complex. Answer: Who
invented the Gram stain and staining method? What are the reagents
,involved? How is Gram stain able to work? What makes some
bacteria gram pos and others neg?
◉ Safranin. Once the decolorizer dissolves the lipid layer holding the
crystal violet-iodine complex, the safranin is able to stain the thin
peptidoglycan layer underneath, causing the bacteria to appear pink.
The pink bacteria can then be identified as Gram neg. Answer: What
is the counter stain that is used alongside Gram stain to identify the
Gram neg bacteria? How does this work?
◉ Cells from a culture are taken and spread over a thin area of a
slide and then heat fixed. The smear doesn't need to be too thin or
too thick, otherwise it will be unable to be read properly. Smears are
heat fixed using a bunsen burner, an electric incinerator, or
methanol. This is done to kill the bacteria on the slide, prevent
bacteria from washing off the slide, and allowing the smear to take
up stain better. Answer: What is smear? What is important when
preparing a smear? How are smears heat fixed and why?
◉ Place the slide on a staining rack and cover the smear with crystal
violet solution. Let stand for 30-60 seconds. Rinse with tap water to
remove the crystal violet, then shake off excess water. Cover the
smear with Gram's iodine and let stand for 30-60 seconds. Rinse
with water, then shale off excess. Decolorize the smear with acetone-
alcohol and rinse with water as soon as the purple/blue color no
longer runs off the slide. *Be careful to not over or under decolorize*
Shake off excess water and counterstain with safranin for 30
, seconds, rinse with water, and dry slide by air or by blotting.
Answer: What is the Gram staining procedure?
◉ Gram neg cells such as human cells will appear washed out and
gram pos bacteria will appear gram neg or partially stained. Gram
neg cells such as human cells will appear dark red / purple and
other gram neg bacteria appear gram pos. Answer: What will
happen is the decolorizer is left on too long? What about under-
decolorized?
◉ Damaged cells are a potential problem when looking at older
culture, they will not take up stain. This can be due to antibiotics.
Overheating a slide distorts cells from their normal shape, causing
them to look weird when viewing. Improper reagent use can be a
source of error when one is omitted or they are used in the wrong
order. Excessive rinsing can wash out the crystal violet or crystal
violent iodine complex away, Prolonged counterstaining might cause
the crystal violet complex to be leached from the Gram pos MOs.
Answer: How will damaged cells pose as a source of error when
staining? How does overheating a slide pose as a source of error?
What about improper reagent use? What about excessive rinsing
and prolonged counterstaining?
◉ Media is used to culture specimens, isolate bacteria, biochemicals
used for identification, and used for antibiotic susceptibility.
Liquid broth, semi-solid agar (0.3-0.5%), agar slants, and solid agar
(1-2%). Polysaccharide is the main component, melting at 100 C and
