Bacteria and Gram Staining

These flashcards cover key concepts related to bacteria, gram staining, and specific pathogens.

Gram Staining

A method that correlates bacterial cell wall structure with sensitivity to antibiotics.

Gram-Positive Bacteria

Bacteria that retain the crystal violet stain and appear purple due to a thick peptidoglycan layer.

Gram-Negative Bacteria

Bacteria that do not retain the crystal violet stain and appear pink or red due to a thinner peptidoglycan layer and the presence of a safranin counterstain.

Peptidoglycan Layer

A polymer consisting of sugars and amino acids that forms a mesh-like layer outside the plasma membrane of bacteria.

Coccus

A type of bacteria that is spherical or round in shape.

Bacillus

A type of bacteria that is rod-like or cylindrical in shape.

Spirillum

A type of bacteria that is helical or spiral in shape.

Filamentous Bacteria

Bacteria that have long, thread-like structures and can form long chains or filaments.

Heterotrophic Bacteria

Bacteria that derive their energy from organic molecules.

Autotrophic Bacteria

Bacteria that derive their energy from photosynthesis or oxidation of inorganic molecules.

Bacteria vs. Archaebacteria

Bacteria typically have a cell wall made of peptidoglycan, while archaebacteria do not.

Bacterial Pathogen

Microorganisms that can cause disease in hosts; examples include anthrax and tuberculosis.

Yersinia pestis

The bacterium that causes bubonic plague; a rod-shaped, gram-negative bacterium.

Streptococcus pyogenes

The bacterium that causes strep throat; spherical and gram-positive.

Staphylococcus epidermidis

A coccus that commonly causes dermal infections; appears spherical and gram-positive.

Salmonella typhi

The bacterium that causes typhoid fever; rod-shaped and gram-negative.

The process of gram-staining

1. prep the smear, heat fix

2. add crystal violet, rinse

3. add iodine, rinse

4. add alcohol - decolorization, rinse

5. add safranin - counterstain, rinse

6. observe under a microscope

Bacillus Anthracis

The bacterium that causes anthrax, rod-shaped and gram positive

Mycobacterium Leprae

The bacterium that causes leprosy, rod-shaped and gram positive

Mycobacterium Tuberculosis

The bacterium that causes tuberculosis, rod-shaped (curved) and neither gram positive nor negative.

Streptococcus Pneumoniae

The bacterium that causes pneumonia, cocci-shaped and gram positive.

Streptococcus Mutans

The bacterium associated with tooth decay, cocci-shaped and gram positive.

Neisseria Meningitidis

The bacterium that causes bacterial meningitis, cocci-shaped and gram negative.

Staphylococcus Epidermis

A bacterium that causes dermal staph infection, coccus, and gram positive

E. coli

A bacterium commonly associated with food poisoning/salmonella, rod shaped, and gram negative