Bacterial anatomy Flashcards by Kathleen Carlos

Shape of diplococci, streptococci, staphylococci?

2 associated cocci
chains of cocci
clusters of cocci

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What general type of bacteria are spherical?

-cocci

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What is a sarcinae?

Pack of 8 cocci arising from alternating cell division planes

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What general bacteria are rod shaped?

Bacilli

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Fusiform shape? Type?

Tapered end

Bacilli

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Clavate/coryneform shape? Type?

Club shaped

Bacilli

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Filamentous shape? Type?

Filamentous

Bacilli

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Vibrios shape? Type?

Comma shaped

Bacilli

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Spirilla shape? Type?

Snake-like

Bacilli

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Coccobacilli shape? Type?

Ovoid or ellipsoid

It is its own type

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Spirochetes shape?

Flexible envelopes and corkscrew appearance

It is its own type

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What are intracytoplasmic granules?

Inclusion bodies or metachromatic granules for storage of energy polymers (glycogen)

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What determines if a bacterium is gram + or - ?

Thickness of the cell wall, which is visualized with a gram stain

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How do you perform a gram stain?

stain with crystal violet (purple) and iodine
destain with acetone and ethanol
counterstain with safranin (red)

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What colors do they bacteria turn with a gram stain?

gram + purple

gram - red

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3 examples of gram + bacteria? Shapes?

Staphylococcus aureus (clusters of spheres)
Streptococcus pneumonia (chain of spheres)
Clostridium botulinum

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Cytoplasmic membrane of gram + bacteria: do they contain sterols?

No (unlike eukaryotes)

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Cytoplasmic membrane of gram + bacteria: do they have integral membrane proteins?

Yes (like eukaryotes)

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Gram + bacteria cell wall is important for which response?

Inflammatory response

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What makes up gram + cell wall? How many layers?

Peptidoglycans

40 layers

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Peptidoglycan synthesis is a target of what?

Antibiotics

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What are lipoteichoic acids? Toxic?

They promote negative surface charge (similar to lipopolysaccharides in gram - bacteria)
They are present in all gram + bacteria
They are nontoxic but contribute to virulence

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3 examples of gram - bacteria? Shapes?

Neisseria gonorrhea - rods
Escherichia coli - rods
Salmonella typhimurium

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Cytoplasmic membrane and cell wall of gram - bacteria?

Cytoplasmic membrane is similar to that of gram +

Cell wall is only 1 layer thick, which is why it doesn’t retain the gram stain

What is the periplasmic space in gram - bacteria?

It is between the inner and outer membranes It contains a peptidoglycan layer and hydrolytic enzymes It also contains detoxifying enzymes (beta-lactamase inactivates penicillin)

Is the outer membrane of gram - bacteria different from the cytoplasmic membrane? What gets through?

Yes, it is less permeable. | Some polar molecules get through, while others have to go through pores

What accounts for the native bacterial resistance of gram - ?

The antibiotics can't get through the outer membrane

What molecule, similar to lipoteichoic acid, do gram - outer membranes contain?

lipopolysaccharide (LPS or endotoxin)

Are gram + or gram - bacteria more resistant to antibiotics?

Gram -

What is responsible for the toxicity of lipopolysaccharide (LPS)?

Lipid A can cause endotoxic shock

What are the three major components of lipopolysaccharide (LPS)?

Lipid A Core oligosaccharide Repeating or O antigen - contains serologic determinants of endotoxin

Porins are major outer membrane proteins that are _____mers. | A porin mutation can create what?

Trimers | Bacterial resistance can result from a porin mutation.

Pores allow solutes less than ______ Daltons to pass through

~700 Daltons

Mycobacteria are what kind of bacteria? 2 examples?

Acid fast bacteria | Tuberculosis and leprae

Mycobacteria usually stain positively with the gram stain because?

They have a lot of waxes in their cell walls. The waxes are made up of mycolic acids. The wax prevents the stain from washing out.

Aside from mycolic acid, what 3 things make up mycobacteria?

Murein Polysaccharides Lipids

Acid fast stain?

1. Stain with carbol-fuchsin (red) and heat 2. Destain with 3% HCl and alcohol 3. Counterstain with methylene blue

What color do acid fast/gram +/- turn with the acid fast stain?

Acid fast turn red | Gram +/- turn blue

Whats an example of mollicutes, which are cell wall deficient bacteria? Is it easy to stain? Antibiotics?

Mycoplasma, which causes walking pneumonia. Difficult to stain Antibiotics won't work

When gram +/- bacteria lose their peptidoglycan coat, what are they called?

L-form/L-phase | They can be selected for clinically by use of antibiotics

Borrelia and treponema are what types of bacteria?

Spirochetes

Clostridium, listeria, bacillus, corynebacterium are what type of bacteria?

Gram + rods

Staphylococcus and streptococcus are what type of bacteria?

Gram + cocci

Myobacterium are what type of bacteria?

Acid fast

What is a capsule? Gram + or - ?

Polysaccharide coat | Both gram +/-

3 capsule types? Describe.

Slime is weakly adherent Microcapsule is a thin coat Biofilm is a growth within layers of polysaccharide, very high resistance that covers the entire colony

How are capsules visualized?

By the exclusion of India ink

What is the Quellung reaction?

Used to serotype bacteria

Do capsules contribute to virulence?

Yes

What 3 factors of capsules help the bacteria avoid host defenses?

Antiphagocytic Interferes with complement Growth in a biofilm prevents access of host cells or antibiotics

What are sex pili? They serve as receptors for what?

Facilitate transfer of DNA during conjugation (bt bacteria) | They serve as receptors for bacteriophages

What are fimbriae or somatic pili?

Allow bacteria to adhere to various surfaces | They are important in infection by some bacteria (neisseria gonorrhea)

Flagella are for what?

Movement (counter clockwise movement moves bacteria toward attractants, which is called positive chemotaxis)

Neisseria and moraxella are examples of what bacteria type?

Gram - cocci

What does -trichous describe?

Distribution of flagella

What are virulence factors?

They enhance the ability of the bacterium to cause infection

Loss of virulence factor can make bacteria what? What happens?

Non-pathogenic Colonization and infection without disease Carrier state

Can a virulence factor be restored?

Yep, can occur rapidly