CCBC Microbiology 230-Summer
2011-Questions #2 Study Set
Why do we heat fix the bacteria to the slide before staining? - Answer So the bacteria
will hold the stain better.
A basic dye has the color in the
_____________ ion - Answer Positive
All bacteria have a slight negative charge; a basic dye has the color in the positive ion.
Opposite charges attract. This is the principle behind: - Answer direct staining
Why do gram positive bacteria appear purple after staining? - Answer The alcohol and
acetone dehydrates
the many layers of peptidoglycan
A bacterial that has one flagella is called what? - Answer Monotrichis.
A bacteria that has flagella all around its outside coat (surrounded by flagella) is called
what? - Answer Peritrichas.
A bacteria that has a flagella that is coming out both ends is called what? - Answer
Lophotricus.
A bacteria that has a single flagella at both poles is called what? - Answer
Amphitrichous.
What are the steps for staining a capsul? - Answer 1) put five loops of bacteria on a slide
from a broth mixture
2) Let mixture dry on slide.
3) add two drops of crystal violet, spread on slide.
4) let slide dry for 1-2 min.
5) flood slide with copper sulfate let sit for 20 seconds.
6) Shake off excess copper sulfate.
7) Blot slide dry.
What are the characteristics of a gram positive cell wall? - Answer 1) Thick dense wall
, 2) contains high levels of peptidogylcan.
3) Wall is composed of teichoic acids
What are the characteristics of a gram negative cell wall? - Answer 1) The cell wall only
contains 2-3 layers of peptidogylcan.
2) Phospholipids are found mainly in the inner layer of the outer membrane
What are the steps to gram stain a bacteria? - Answer 1) Stain bacteria with crytal violet
2) Then treat bacteria with gram's iodine solution.
3) Add grams decolorizer
4) Add safranin.
What type of charge do bacteria have? - Answer Bacteria have a slightly negative
charge.
What are the basic dyes? - Answer the basic dyes are methylene blue, crystal violet and
safrain.
What is a direct stain? - Answer The bacteria will hold the stain inside of the cell.
What is an indirect stain? - Answer The bacteria will not let the stain come into its cell,
so the stain colors around the bacteria.
What are the steps to directly stain bacteria? - Answer 1) Put one drop of water on a
slide
2) aseptically remove some bacteria and mix it into the water.
3) Spread the mixture over the slide.
4) Let slide dry.
5) Pass slide through flame 12 times to heat fix bacteria.
6) Cover slide with safrain and let sit for 1 minute.
7) Wash slide.
8) Blot slide dry.
What are the steps to indirectly stain bacteria? - Answer 1) Put one drop of nigrosin on
slide.
2) Aseptically add a small amount of bacteria and mix with dye.
3) Use another slide to spread bacteria on slide.
2011-Questions #2 Study Set
Why do we heat fix the bacteria to the slide before staining? - Answer So the bacteria
will hold the stain better.
A basic dye has the color in the
_____________ ion - Answer Positive
All bacteria have a slight negative charge; a basic dye has the color in the positive ion.
Opposite charges attract. This is the principle behind: - Answer direct staining
Why do gram positive bacteria appear purple after staining? - Answer The alcohol and
acetone dehydrates
the many layers of peptidoglycan
A bacterial that has one flagella is called what? - Answer Monotrichis.
A bacteria that has flagella all around its outside coat (surrounded by flagella) is called
what? - Answer Peritrichas.
A bacteria that has a flagella that is coming out both ends is called what? - Answer
Lophotricus.
A bacteria that has a single flagella at both poles is called what? - Answer
Amphitrichous.
What are the steps for staining a capsul? - Answer 1) put five loops of bacteria on a slide
from a broth mixture
2) Let mixture dry on slide.
3) add two drops of crystal violet, spread on slide.
4) let slide dry for 1-2 min.
5) flood slide with copper sulfate let sit for 20 seconds.
6) Shake off excess copper sulfate.
7) Blot slide dry.
What are the characteristics of a gram positive cell wall? - Answer 1) Thick dense wall
, 2) contains high levels of peptidogylcan.
3) Wall is composed of teichoic acids
What are the characteristics of a gram negative cell wall? - Answer 1) The cell wall only
contains 2-3 layers of peptidogylcan.
2) Phospholipids are found mainly in the inner layer of the outer membrane
What are the steps to gram stain a bacteria? - Answer 1) Stain bacteria with crytal violet
2) Then treat bacteria with gram's iodine solution.
3) Add grams decolorizer
4) Add safranin.
What type of charge do bacteria have? - Answer Bacteria have a slightly negative
charge.
What are the basic dyes? - Answer the basic dyes are methylene blue, crystal violet and
safrain.
What is a direct stain? - Answer The bacteria will hold the stain inside of the cell.
What is an indirect stain? - Answer The bacteria will not let the stain come into its cell,
so the stain colors around the bacteria.
What are the steps to directly stain bacteria? - Answer 1) Put one drop of water on a
slide
2) aseptically remove some bacteria and mix it into the water.
3) Spread the mixture over the slide.
4) Let slide dry.
5) Pass slide through flame 12 times to heat fix bacteria.
6) Cover slide with safrain and let sit for 1 minute.
7) Wash slide.
8) Blot slide dry.
What are the steps to indirectly stain bacteria? - Answer 1) Put one drop of nigrosin on
slide.
2) Aseptically add a small amount of bacteria and mix with dye.
3) Use another slide to spread bacteria on slide.
