Microbiology Basics – Bacteria, Viruses & Fungi

Vocabulary flashcards covering key terms from the lecture on microorganism characteristics, bacterial morphology, growth control, viral life cycle, and basic mycology.

Bacteria

Single-celled microorganisms whose species are distinguished by shape, size, nutrient needs and oxygen tolerance.

Gram Stain

Laboratory staining method that differentiates bacteria into Gram-positive or Gram-negative based on cell-wall properties.

Gram-Positive

Bacteria that retain crystal-violet stain and appear blue or purple under a microscope.

Gram-Negative

Bacteria that lose crystal-violet stain and take up safranin, appearing red or pink.

Morphology (of bacteria)

The study of bacterial cell shape and size used to classify species.

Cocci

Spherical (round) bacteria; name remembered by the many round letters in the word COCCI.

Bacilli

Rod-shaped bacteria; easy to recall by the rod-like letters ‘I’ and ‘l’ in the word.

Spirilla

Spiral-shaped bacteria; the word itself contains the hint ‘spiral.’

Growth Requirements

Specific physical or chemical conditions (oxygen, temperature, pH, nutrients, etc.) a bacterium needs to multiply.

Optimal pH for Human Bacteria

Around pH 7 (neutral), though most survive between pH 5.5 and 8.5.

Bacterial Doubling Time

The interval—sometimes as fast as 20 minutes—needed for bacteria to double in number under ideal conditions.

Control of Bacterial Growth

Preventing multiplication or killing bacteria through physical or chemical means.

Physical Agents (Control)

Methods such as heat or friction that destroy or inhibit bacteria.

Chemical Agents (Control)

Disinfectants or antiseptics that kill or inhibit bacteria depending on location and species.

Virus

Ultramicroscopic infectious agent that requires a living host cell to replicate.

Host (Virology)

The living cell or organism a virus attaches to and invades for replication.

Capsid

Protein coat of a virus that encloses its nucleic acid and is removed after entry into the host cell.

Lytic Cycle

Viral replication pathway that culminates in host-cell lysis and release of new virions.

Persistent Infection

Viral condition in which the virus remains within the host cell without immediate lysis, continually producing new particles.

Cell Transformation (Viral)

Change of a host cell’s properties—often toward uncontrolled growth—induced by viral nucleic acid.

Fungi

Kingdom of organisms including mushrooms, molds and yeasts; may become pathogenic when growth is unchecked.

Yeast

Unicellular fungi; normally present in the body but can overgrow and cause disease.

Opportunistic Infection

Disease caused when normally harmless microbes (e.g., yeasts) proliferate under favorable conditions.

Candida albicans

Common yeast species that can cause thrush and other candidiasis infections in humans.

Ringworm

Fungal (dermatophyte) skin infection characterized by ring-shaped lesions.

Athlete’s Foot

Fungal infection (tinea pedis) affecting the skin of the feet.