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What are the minimum requirements of a bacterial cell?
- Cytoplasm
- Ribosomes
- Nucleoid
- Plasma membrane
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What are MAMPs?
- Microbe associated molecular patterns
- Only found on bacterial cells
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Examples of MAMPs
- Teichoic acids
- Peptidoglycan
- LPS
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The cytoplasm of a bacterial cell is packed with __________________ because they are rapidly dividing
Ribosomes
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The _________________ in a bacterial cell contains its DNA
Nucleoid
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What membrane bound organelles do bacterial cells have?
None
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What is the chemical composition of Gr+ cell envelopes?
- Peptidoglycan
- Plasma membrane
- Teichoic acids/lipoteichoid acids
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What is the chemical composition of Gr- cell envelopes?
- Outer membrane
- Peptidoglycan
- Periplasmic space
- Plasma membrane
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What determines whether a bacterium will react to a gram stain or not?
The wall of the cell envelope
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Gram ________________ bacteria have thicker peptidoglycan walls compared to gram _________________ bacteria
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Teichoic acids are found only in gram ____________ bacteria
Positive
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Bacterial cell wall is made up of ________________
Peptidoglycan
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Teichoic acids are _____________ charged and contribute towards _______________
-
Peptidoglycan is _______________ charged and contribute towards ________________
- Negatively
- Stability and shape
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What are peptidoglycans composed of?
Repeating NAM-NAG crosslinked by amino acids
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Lysozymes target _______________ on a bacterium and penicillin targets _________________. These two combined causes…
- NAM-NAG bond
- Cross link of peptide chains
- Wall to fall apart
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Where is LPS located on a bacterial cell and which type of cells have it?
- Outer leaflet of outer membrane
- Gram negative bacteria
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Lipopolysaccharide causes gram-negative cells to be relatively _______________ because it is ________________
-
What is an example of a bacterial capsule former?
Streptococcus pneumoniae
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What are examples of endospore formers?
- Clostridium dificile
- Bacillus
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Porin proteins are found on _____________ bacteria and function to …
- Gram-negative
- Allow passage of hydrophilic solutes
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______________ in gram-_____________ bacteria is the most common cause for septic shock
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What are the 3 parts of a lipopolysaccharide (LPS) from external to internal?
- O-antigen
- Core oligosaccharide
- Lipid A
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Lipid A is aka ______________
Endotoxin
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Which of the cell envelopes provides a barrier to many hydrophobic antibiotics and detergents?
Gram-negative bacteria
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Which of the cell envelopes contains porins?
Gram-negative bacteria
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Which of the cell envelopes contains up to 40 layers of peptidoglycan?
Gram-positive bacteria
-
Which of the cell envelopes is most susceptible to penicillin?
Gram-positive bacteria
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What is the difference between a simple stain and a gram stain?
- A simple stain stains all bacteria
- A gram stain will tell you whether it is gram-positive or gram-negative, morphology, and arrangement
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What are the steps of staining using a gram stain?
- 1. Fixation
- 2. Crystal violet (simple stain)
- 3. Iodine treatment
- 4. Decolorization
- 5. Counter stain safranin
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In which steps of the gram stain process do gram-negative and gram-positive look different?
- Decolorization—gram-negative bacteria will become colorless (thin wall) and gram-positive bacteria will stay purple
- Counter stain safranin—gram-negative bacteria will become pink and gram-positive bacteria will stay purple
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A gram-negative bacterium is subjects to the gram-staining procedure by an inexperienced technician who forgets to decolorize. What color will the bacterial cells most likely be at the end of the Gram-staining protocol?
Purple
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What is special about mycoplasma?
Don’t have a cell wall
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What is the shape of mycoplasma?
Pleomorphic (many shapes)
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Since mycoplasma have no cell wall, how are they stable?
Have sterols in plasma membrane
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Does the gram stain work for mycoplasma?
No
-
Mycoplasma aka _______________
Ureaplasma
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What do lysozymes do to mycoplasma?
Nothing
-
What does penicillin do to mycoplasma?
Nothing
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What is special about chlamydia?
It is an obligate intracellular bacterium and can’t synthesize ATP
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What stain would you use for chlamydia? Is it gram-positive or gram-negative?
- Don’t gram-stain because small and intracellular
- Gram-negative
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Do gram-stains work for mycobacteria? Why or why not?
No, because they have mycolic acids which do not take the stain
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Are mycobacteria gram-positive or gram-negative?
Neither
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Instead of calling mycobacteria gram-positive, we call them __________________
Acid-fast
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______________ are very hydrophobic because of their _________________
- Mycobacteria
- Mycolic acids
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What are the steps in an acid-fast stain
- 1. Carbol fuchsin (turns both acid-fast and nonacid-fast fuschia)
- 2. Acid alcohol decolorizer (turns nonacid-fast light pink)
- 3. 2nd stain (turns nonacid-fast the color of that 2nd stain)
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Mycobacterium tuberculosis stains well with the acid-fast stain, but not with the Gram stain. What is the best explanation for this?
It has a large amount of lipid (mycolic acids) that prevents entry of crystal violet
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Are capsules found on gram-positive or gram-negative bacteria?
Can be found on both
-
Capsule found inside/outside of cell wall
Outside
-
What are capsules made of?
Polysaccharides
-
What is the structure that gives pathogenic bacteria protection from the immune system?
Capsules
-
What is the major role of a capsule?
It is antiphagocytic (protection against immune system)
-
What staining methods do you use for capsules?
- Stain background with acidic stain
- Stain cell with simple stain
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Endospores are gram _____________ and ______________ shaped
-
Endospores tend to live in ________________
Soil
-
Endospore activity when outside of host
They are dormant and inactive
-
Do endospores stain?
Very hard to stain, need heat to stain
-
Sporulation usually happens in __________________
Adverse growth conditions (no nutrients, dry conditions)
-
What is germination?
Endospore converts back to replicating cell (favorable growth conditions)
-
Endospore vs. vegetative cell
Vegetative cell is the actively replicating normal function bacterium
-
What is sporulation?
Bacteria --> endospore
-
What is germination?
Endospore --> bacteria
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What is the function of flagella?
Motility and penetration
-
Flagella is made of ______________
Flagellin
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How can you stain flagella?
You need lots of thick layers of stain to see it
-
What is the function of pili (fimbriae)?
Attachment to tissue
-
What are pili (fimbriae) made of?
Pilin
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The antigenic portion of LPS is __________________
O side chain
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Streptococcus is gram-positive. What color will it be at the end of the gram stain?
Purple
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How can you tell if a stain is an endospore?
Stains are within the bacteria
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Identify shape of bacteria
Bacilli
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Identify shape of bacteria
Coccus
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Identify shape of bacteria
Vibrio
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Identify shape of bacteria
Spirochete
-
Strept- means _____________
Chained
-
Staph- means ______________
Grape-like clusters
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