Microbiology & Prokaryotic/Eukaryotic Microbes Flashcards

Vocabulary practice flashcards covering Lectures 1 through 4 on introductory microbiology, prokaryotic and eukaryotic microbes, and viruses.

Free-living microorganism

A microorganism that can obtain everything it needs from the nonliving environment.

Parasitic microorganism

A microorganism that depends on a host for survival or replication.

Obligate intracellular parasite

An organism, such as a virus, that must reside inside a host cell to replicate.

Binomial nomenclature

The system of naming organisms using a two-part scientific name consisting of the genus and species.

Coccus

A round-shaped bacterial cell.

Bacillus

A rod-shaped bacterial cell.

Vibrio

A curved rod-shaped bacterial cell.

Spirillum

A rigid, helix-shaped bacterial cell.

Spirochete

A flexible, longer helix-shaped bacterial cell.

Pleiomorphism

Variation in shape and size among cells of the same bacterial species.

Peptidoglycan (PG)

A mesh-like polymer of long glycan chains cross-linked by short peptide fragments that forms the bacterial cell wall.

Lysozyme

An enzyme that hydrolyzes bonds in the glycan chains of peptidoglycan.

Penicillin

An antibiotic that targets the peptide cross-links in peptidoglycan.

Gram-positive cell envelope

A bacterial cell envelope containing a thick peptidoglycan layer ($20\text{--}80\,nm$), teichoic acid, lipoteichoic acid, and a cell membrane, lacking an outer membrane.

Gram-negative cell envelope

A bacterial cell envelope containing an outer membrane with lipopolysaccharide (LPS) and porins, a periplasmic space, a thin peptidoglycan layer ($1\text{--}3\,nm$), and an inner cell membrane.

Lipopolysaccharide (LPS)

A component of the outer leaflet of Gram-negative outer membranes that provides structural support and acts as a strong antigen.

Porins

Proteins located in the outer membrane of Gram-negative bacteria that allow certain small molecules to pass through.

Periplasmic space

The fluid-filled region between the outer membrane and cell membrane in Gram-negative bacteria containing water, hydrolytic enzymes, detoxifying enzymes, and binding proteins.

Mycoplasma

A genus of bacteria that naturally lacks a cell wall.

Acid-fast bacteria

Bacteria, such as Mycobacterium, whose cell walls contain large amounts of unique lipids that contribute to drug resistance.

Gram stain

A differential staining procedure using crystal violet, iodine, alcohol, and safranin to distinguish Gram-positive (purple) from Gram-negative (pink) bacteria.

Flagellum

A bacterial appendage responsible for cell motility, composed of a basal body, hook, and filament made of the protein flagellin.

Chemotaxis

Cellular movement in response to chemical signals, characterized as positive (toward an attractant) or negative (away from a repellent).

Fimbriae

Short, flexible, hair-like bacterial structures that function in attachment to surfaces, host cells, and other bacteria.

Sex pilus

A rigid, hollow hair-like structure that mediates conjugation, enabling DNA transfer from a donor bacterium to a recipient bacterium.

Glycocalyx

A surface layer composed of polysaccharides and proteins surrounding certain bacterial cells, existing as either a loose slime layer or a tightly bound capsule.

Biofilm

A complex aggregation of microbes growing together attached to a surface.

Bacterial chromosome

A single, circular piece of double-stranded DNA located in the cytoplasm containing essential genes required for survival and growth.

Plasmids

Small, circular pieces of non-chromosomal DNA carrying nonessential protective genes, such as antibiotic resistance or virulence factors.

Endospores

Dormant structures produced by certain bacteria (such as Bacillus and Clostridium) that enable survival under harsh, unfavorable conditions.

Sporulation

The process of forming a dormant endospore triggered by unfavorable environmental conditions such as nutrient depletion, desiccation, or extreme heat.

Germination

The process where a dormant bacterial spore returns to an active vegetative cell state upon exposure to favorable conditions.

Eukaryotic flagella

Membrane-bound locomotor structures containing a $9 + 2$ arrangement of microtubules used for cellular propulsion.

Cilia

Short, numerous cell projections found in certain protozoa that move in coordinated waves for locomotion.

Rough endoplasmic reticulum (RER)

A membrane-bound organelle studded with ribosomes that performs protein synthesis.

Smooth endoplasmic reticulum (SER)

A membrane-bound organelle involved in lipid synthesis as well as lipid and carbohydrate metabolism.

Golgi apparatus

An organelle that modifies, packages, and ships cellular proteins.

Mitochondria

Double-membraned eukaryotic organelles with inner cristae and unique DNA that produce ATP through cellular respiration.

Lysosomes

Membrane-bound vesicles containing hydrolytic enzymes responsible for digesting cellular materials.

Yeasts

Unicellular fungi that exist primarily as single oval-shaped cells and reproduce by budding or fission.

Pseudohyphae

Chains of elongated yeast cells that remain attached after division, resembling true hyphae.

Hyphae

Long, thread-like fungal filaments classified as vegetative (growth/feeding) or reproductive (spore-producing).

Mycelium

The woven mass or network composed of interconnected fungal hyphae.

Mycosis

A fungal infection, frequently caused by opportunistic pathogens when host defenses are weakened.

Trophozoite

The active, feeding, and growing stage of a protozoan lifecycle.

Cyst

The dormant, resistant survival stage formed by a protozoan when environmental conditions become unfavorable.

Pseudopods

Temporary cytoplasmic extensions used by certain protozoa for cellular movement.

Capsid

The protein shell surrounding viral nucleic acid, composed of repeating protein subunits called capsomers.

Nucleocapsid

The structural unit consisting of the viral protein capsid together with its enclosed nucleic acid core.

Viral envelope

A lipid membrane outer layer surrounding the capsid in some animal viruses, acquired during budding.

Spikes

Surface protein projections on animal viruses that bind to specific host cell receptors during viral adsorption.

Reverse transcriptase

A viral enzyme that synthesizes DNA from a viral RNA template following the sequence: $\text{RNA} \rightarrow \text{DNA} \rightarrow \text{mRNA} \rightarrow \text{protein}$.

Adsorption

The initial stage of viral replication where viral spikes bind specifically to receptors on the host cell membrane.

Uncoating

The viral entry step in which the viral envelope or capsid is removed, releasing viral nucleic acid into the host cell.

Persistent infection

A viral infection in which the virus remains inside host cells for long durations without causing immediate cell destruction.

Provirus

Viral DNA that has integrated into the genomic DNA of a host eukaryotic cell.

Viral transformation

An alteration in a host cell caused by a virus that results in uncontrolled cell growth and potential cancer.

Bacteriophage

A virus that infects bacterial cells, typically possessing double-stranded DNA and a complex capsid shape.

Lytic cycle

A bacteriophage lifecycle consisting of adsorption, penetration, synthesis, assembly, maturation, and cell lysis, resulting in host cell destruction.

Lysogenic cycle

A bacteriophage lifecycle in which viral DNA integrates into the host chromosome as an inactive prophage and replicates alongside the host.

Prophage

Inactive bacteriophage DNA that is incorporated into the host bacterial chromosome.

Induction

The activation step in which an inactive prophage leaves the bacterial chromosome to enter the lytic cycle.

Lysogenic conversion

The acquisition of a new, inheritable trait by a bacterium from an integrated temperate bacteriophage.