Microbiology Lab Exam 3- 2023/ 125
Questions and Answers / Verified.
What is the purpose of a streak plate? - -1) To separate cells so that they grow to form
isolated colonies 2) To confirm if a culture is a pure colony or mixed 3) To confirm is
there is contamination in your culture
-What is a colony? - -Areas of growth that arise from a single cell.
-How do colonies form? - -They are formed by spreading out cells. Cells are spread and
reproduce over and over again through bionary fission until visable mass of cells appear.
-What is a pure culture? - -Culture containing only one type of organism
-What kind of media are colonies able to form on? - -agar slant, broth media, agar plate
-When is a agar slant used? Pros & cons - -1) Smaller amount of surface area prevents
the media from drying out too quickly 2) useful for medium term storage 3) viable for a
couple of months if stored properly
-What are the 4 criteria for labeling a microbial culture? - -1) initials or name AND
group number
2) date
3) growth media type
4) culture name or source of inoculum
-Describe bacillus (bacilli) morphology - -rod shaped cells, longer than wide, sausage
like, can use rod or bacillus
-describe coccus morphology - -cells are ball shaped or spherical
-Describe coccobacillus morphology - -elongated spheres- not quite spherical, but not
clearly a rod. Tends to occur in species which are normally rod-shaped during rapid
growth.
-Describe spirillum morphology - -Helical, loose or tight coils. Look like wavy lines -
morphology has no arrangement
, -Describe filamentous morphology - -Long elongated cells. Look like a tangled mass of
branched filaments- no arrangement
-Describe vibrio morphology - -A curved rod or comma shape
-What does No arrangement mean? - -Single cells, ungrouped. Not all cells have an
arrangement
-What is the cell arrangement Diplococci/Diplobacilli - -Pairs of cells. Diplococci are
pairs of cocci, diplobacilli are pairs of rods
-What is the cell arrangement Streptococci/Streptobacilli? - -Chains of cells.
Streptococci are chains of cocci, streptobacilli are chains of rods
-What is the call arrangement staphylococcus? - -Irregular clusters of cells- like
bunches of grapes.
-What is the cell arrangement of tetrads? - -Sets of 4 regularly arranged cells
-What is the cell arrangement of palisade? - -Bacilli (usually 2-4 cells) arranged side by
side. Columns or "V-forms"
-What genus is an acid fast bacteria? - -Mycobacterium tuberculosis
-What genus is an capsule former? - -Klebsiella pneumoniae
-What is a simple stain? - -Involves only one dye to make cells more visable. Involves
methylene blue or crystal voilet.
-What is a complex stain? - -Two or more stains. Allow the differentiation of cell types
or cell structures. (can be called differential stain)
-What is a differential stain? - -Another name for complex stain. Allow us to see the
differences between different cell types or cell structures. Uses at least two different
stains.
-What is a negative stain? - -Leaves cell or a cell structure unstained while the
background is stained. No heat fixing. Used to determine cell shapes more accurately or
to see structures which may be unable to accept dyes, or which are adversely affected by
heat fixation (capsules)
Questions and Answers / Verified.
What is the purpose of a streak plate? - -1) To separate cells so that they grow to form
isolated colonies 2) To confirm if a culture is a pure colony or mixed 3) To confirm is
there is contamination in your culture
-What is a colony? - -Areas of growth that arise from a single cell.
-How do colonies form? - -They are formed by spreading out cells. Cells are spread and
reproduce over and over again through bionary fission until visable mass of cells appear.
-What is a pure culture? - -Culture containing only one type of organism
-What kind of media are colonies able to form on? - -agar slant, broth media, agar plate
-When is a agar slant used? Pros & cons - -1) Smaller amount of surface area prevents
the media from drying out too quickly 2) useful for medium term storage 3) viable for a
couple of months if stored properly
-What are the 4 criteria for labeling a microbial culture? - -1) initials or name AND
group number
2) date
3) growth media type
4) culture name or source of inoculum
-Describe bacillus (bacilli) morphology - -rod shaped cells, longer than wide, sausage
like, can use rod or bacillus
-describe coccus morphology - -cells are ball shaped or spherical
-Describe coccobacillus morphology - -elongated spheres- not quite spherical, but not
clearly a rod. Tends to occur in species which are normally rod-shaped during rapid
growth.
-Describe spirillum morphology - -Helical, loose or tight coils. Look like wavy lines -
morphology has no arrangement
, -Describe filamentous morphology - -Long elongated cells. Look like a tangled mass of
branched filaments- no arrangement
-Describe vibrio morphology - -A curved rod or comma shape
-What does No arrangement mean? - -Single cells, ungrouped. Not all cells have an
arrangement
-What is the cell arrangement Diplococci/Diplobacilli - -Pairs of cells. Diplococci are
pairs of cocci, diplobacilli are pairs of rods
-What is the cell arrangement Streptococci/Streptobacilli? - -Chains of cells.
Streptococci are chains of cocci, streptobacilli are chains of rods
-What is the call arrangement staphylococcus? - -Irregular clusters of cells- like
bunches of grapes.
-What is the cell arrangement of tetrads? - -Sets of 4 regularly arranged cells
-What is the cell arrangement of palisade? - -Bacilli (usually 2-4 cells) arranged side by
side. Columns or "V-forms"
-What genus is an acid fast bacteria? - -Mycobacterium tuberculosis
-What genus is an capsule former? - -Klebsiella pneumoniae
-What is a simple stain? - -Involves only one dye to make cells more visable. Involves
methylene blue or crystal voilet.
-What is a complex stain? - -Two or more stains. Allow the differentiation of cell types
or cell structures. (can be called differential stain)
-What is a differential stain? - -Another name for complex stain. Allow us to see the
differences between different cell types or cell structures. Uses at least two different
stains.
-What is a negative stain? - -Leaves cell or a cell structure unstained while the
background is stained. No heat fixing. Used to determine cell shapes more accurately or
to see structures which may be unable to accept dyes, or which are adversely affected by
heat fixation (capsules)
