Bacteria Form and Function

Bacteria are single-celled microorganisms that are among the most abundant and diverse life forms on Earth. They are prokaryotic, which means their cells lack a nucleus and other membrane-bound organelles found in more complex organisms like plants, animals, and fungi.

Bacteria are classified based on various characteristics, including their morphology (shape and structure), staining properties, biochemical properties, and genetic makeup.

1. Bacteria are classified into two kingdoms:

Eubacteria (true bacteria)
Archaebacteria (Ancient Bacteria).

2. BACTERIA are microscopic prokaryotes.  (“before nucleus”)

3. Adapted to living in all environments (even some extreme) – they exist everywhere

Bacterial Structure


II.  Reproduction in Prokaryotesfission

Binary fission is the splitting of a parent cell into two daughter cells; it is asexual reproduction in prokaryotes.

In bacteria, genetic recombination can occur in three ways.

1. Conjugation

2. Transformation

3. Transduction

III.  Prokaryotic Nutrition

Anaerobic / Aerobic

Autotroph ( Chemotroph or Photosynthetic ) / Heterotroph

Mutualists (symbiotic) nitrogen‑fixing Rhizobium bacteria / Gut bacteria in humans


1.  Three basic shapes: coccus / bacillus / spirillum


2. Those shapes can be organized into

staph = clusters / strep = chains


A. Bacillus B. Streptococcus C. Staphylococcus D. Diplococcus E. Spirllum F. Vibrio

3. Gram Stains

Used to identify bacteria / Gram Positve = dark purple / Gram Negative = pink

gram stain process

VI. Bacteria and Health

Streptococcus strep throat, related bacteria causes necrotizing fasciitis
Staphylococcus aureas

found on skin, responsible for minor infections, boils, pimples; MRSA is an antibiotic resistant form; some strains cause necrotizing fasciitis

Bacillus tetani causes tetanus (lockjaw), most people are vaccinated
Clostridium botulism causes botulism (food poisoning)
Yersinia (bacillus) pestis causes Black Plague
Bacillus anthracis anthrax
Mycoplasmas very tiny, cause of pneumonia
Salmonella Belongs to same family as E. coli, also causes food poisoning
STreponema pallidum Spiral shaped bacteria, syphilis
Escherichia coli E. coli - common bacteria of the digestive tract, causes food poisoning, GRAM NEGATIVE
Bacillus Subtilis Hay bacteria, easy to grow in lab, GRAM POSITIVE

Antibiotics and Antiseptics

Joseph Lister / Antiseptics

Alexander Fleming / Penicillin (1945, Nobel prize)