Unit 3 – Prokaryotes, Eukaryotes & Viruses: Vocabulary Flashcards

42 vocabulary flashcards covering key terms from prokaryote characteristics, classification, archaea, phototrophy, Gram positives & negatives, arthropod vectors, and viral structure, replication and prion biology.

Vibrio

A slightly curved, comma-shaped rod-like prokaryotic cell morphology.

Pleomorphic prokaryote

A prokaryote whose cell shape and size vary rather than remaining uniform.

Binary fission

Primary asexual reproductive process in prokaryotes in which one cell divides into two genetically identical cells.

Snapping division

A form of binary fission in some Gram-positive rods where tension in the cell wall causes the daughter cells to snap apart at a hinge.

Budding (bacterial)

Reproductive method where a daughter cell develops as an outgrowth of the parent cell before separating.

Spore (bacterial)

A reproductive structure produced by some bacteria for dissemination—not for dormancy or survival under stress.

Endospore

A highly resistant, non-reproductive resting structure formed inside certain bacteria for survival under harsh conditions.

Taxonomic domain

The highest rank in biological classification; the three recognized domains are Archaea, Bacteria and Eukarya.

Archaea

A domain of prokaryotes lacking peptidoglycan, possessing branched lipid membranes and unique rRNA sequences.

Bacteria

Domain of prokaryotes characterized by peptidoglycan cell walls and unbranched lipid membranes.

Eukarya

Domain that includes all organisms with membrane-bound nuclei (eukaryotes).

rRNA gene sequencing

Classification tool that uses conserved and variable regions of ribosomal RNA genes present in all bacteria.

Extremophile

A microbe that requires extreme temperature, pH and/or salinity to survive.

Thermophile

Organism that grows optimally between about 45 °C and 80 °C.

Hyperthermophile

Organism that requires temperatures above 80 °C for growth.

Halophile

Microbe that requires environments containing more than 9 % NaCl.

Methanogen

Obligate anaerobe that converts CO₂, H₂ and organic acids to CH₄ (methane).

Autotrophic bacterium

Bacterium that produces organic compounds from carbon dioxide.

Phototrophic bacteria

Bacteria classified by their photosynthetic pigments and electron sources used in photosynthesis.

Nitrogen fixation

Reduction of atmospheric nitrogen gas (N₂) to ammonia (NH₃) by certain microbes.

G + C content

Percentage of guanine and cytosine bases in an organism’s DNA; used to assess genetic relatedness.

Mycoplasma

Wall-less, pleomorphic, low-G + C Gram-positive bacteria that can colonize humans.

Corynebacterium

Gram-positive rods with metachromatic granules that reproduce by snapping division; high G + C content genus.

Lyme disease

Tick-borne illness caused by Borrelia burgdorferi.

Rocky Mountain spotted fever

Tick-borne disease caused by Rickettsia rickettsii.

Tularemia

Tick-borne (and other vector) disease caused by Francisella tularensis.

Malaria

Mosquito-borne protozoan disease; not transmitted by ticks.

Female mosquito

The sex of mosquito that feeds on blood and transmits pathogens.

Helminth

Parasitic worm studied in microbiology because its microscopic eggs and larvae aid clinical diagnosis.

Virion

Complete infectious virus particle consisting of a nucleic acid core enclosed in a protein capsid, with or without an envelope.

Capsomere

Protein subunit that assembles to form a viral capsid.

Capsid

Protein coat that surrounds and protects viral nucleic acid.

Lytic replication

Viral reproduction cycle that culminates in host-cell death and lysis, releasing progeny virions.

Prophage

Phage genome integrated into the host bacterial chromosome during lysogeny.

Induction (lysogeny)

Excision of prophage DNA from the host genome, triggering a switch to the lytic cycle.

Retrovirus

RNA virus that carries reverse transcriptase within its capsid to synthesize DNA from its RNA genome.

Plaque assay

Inexpensive method for estimating phage numbers by counting clear zones (plaques) on a bacterial lawn.

Diploid cell culture

Virus-propagation system derived from embryonic or other primary animal cells that undergo a limited number of divisions.

Viroid

Small circular single-stranded RNA molecule without a capsid that infects plants.

Prion

Infectious, misfolded protein capable of inducing normal cellular PrP to misfold.

Spongiform encephalopathy

Neurodegenerative disease caused by prions, producing sponge-like brain tissue.

Reverse transcriptase

Enzyme that synthesizes complementary DNA (cDNA) from an RNA template; carried by retroviruses.