Microbiology Lecture Review: Chapters 1 to 6 - Prokaryotes, Eukaryotes, Cell Structure & Archaea

Comprehensive vocabulary flashcards covering prokaryotic and eukaryotic distinctions, cellular organelles, microbial taxonomy, historical experiments, cell membrane transport, cell wall structures, endospores, and archaeal biochemistry.

70S Ribosome

The prokaryotic ribosome composed of a $30\text{S}$ small subunit and a $50\text{S}$ large subunit, containing $16\text{S}$ rRNA.

80S Ribosome

The eukaryotic ribosome composed of a $40\text{S}$ small subunit and a $60\text{S}$ large subunit, containing $18\text{S}$ rRNA.

Three Domains of Life

The classification system categorizing all cellular life into Bacteria, Archaea, and Eukarya.

RNA World Hypothesis

The theory proposing that RNA was the original genetic material and catalyst of early life.

LUCA (Last Universal Common Ancestor)

The ancestral cell population from which cellular domains—Bacteria, Archaea, and Eukarya—originally evolved.

Endosymbiotic Hypothesis

The theory that organelles such as mitochondria and chloroplasts originated from free-living prokaryotes engulfed by larger host organisms.

Genomic Reduction

The evolutionary loss of genes in an endosymbiont when equivalent metabolic functions are performed by the host cell.

Horizontal Gene Transfer (HGT)

The non-genealogical movement of genetic information between organisms, occurring via conjugation, transduction, or transformation.

Conjugation

A mechanism of horizontal gene transfer mediated by direct cell-to-cell contact and a sex pilus.

Binomial Nomenclature

The formal system of naming species combining an italicized, capitalized Genus name followed by an italicized, lowercase species epithet.

Bergey's Manual of Systematic Bacteriology

The primary standard scientific reference used to identify and categorize bacterial taxa.

ATCC (American Type Culture Collection)

A major global nonprofit bioresource center used to store, maintain, and distribute authentic microbial strains.

Robert Hooke

The scientist who first coined the term cell while examining cork tissues.

Antoni van Leeuwenhoek

The first person to accurately observe and describe microscopic organisms using handcrafted single-lens microscopes.

Francesco Redi

The scientist who challenged spontaneous generation by demonstrating that maggots arise from fly eggs rather than decaying meat.

John Needham

A proponent of spontaneous generation who boiled nutrient broth before sealing flasks, resulting in microbial growth due to contamination.

Lazzaro Spallanzani

A scientist who disproved Needham's findings by sealing broth flasks prior to boiling, proving micro-organisms enter from the air.

Louis Pasteur

The scientist who definitively disproved spontaneous generation using swan-neck flasks, developed pasteurization, and discovered attenuation.

Pasteurization

A controlled heat treatment process designed to reduce pathogenic microbial loads without achieving total sterilization.

Sterilization

The absolute destruction or elimination of all viable microorganisms, including bacterial endospores.

Joseph Lister

The pioneer of antiseptic surgery who used phenol to kill microbes on surgical tools, leading to the naming of Listerine.

Koch's Postulates

A set of four criteria used to establish a direct causal link between a specific microorganism and a specific infectious disease.

Attenuation

The process of weakening a pathogen's virulence so that it remains alive but can no longer induce severe disease.

Tissue Tropism

The specific receptor requirement of a pathogen that limits its ability to infect only particular host cells or species.

Edward Jenner

The physician who created the first successful vaccine using cowpox material to grant immunity against smallpox.

Coccus

A bacterial cell exhibiting a spherical or circular shape.

Bacillus

A bacterial cell exhibiting a rod shape.

Vibrio

A bacterial cell displaying a curved, comma-like shape.

Pleomorphic

Bacteria that naturally variable in cell shape or lack a single defined morphology.

Staphylococcus

A cellular arrangement characterized by irregular, grape-like clusters of cocci.

Streptococcus

A cellular arrangement characterized by chains of connected cocci.

Palisades

A cellular arrangement where rod-shaped bacterial cells align parallel to one another in a fence-like distribution.

Surface Area-to-Volume Ratio (S/V Ratio)

A biological parameter calculated as $\text{S/V} = 3/r$ for spherical cells, where higher values enhance nutrient diffusion efficiency.

FtsZ

A bacterial cytoskeletal protein homologous to eukaryotic tubulin that forms a ring structure during cell division.

MreB

A bacterial cytoskeletal protein homologous to actin that determines rod shape in bacilli.

CreS (Crescentin)

A bacterial cytoskeletal protein homologous to intermediate filaments that induces cellular curvature in vibrio-shaped bacteria.

Magnetosomes

Non-storage intracellular inclusions containing iron oxides that allow aquatic bacteria to orient along Earth's magnetic lines.

Gas Vacuoles

Proteinaceous intracellular inclusions providing buoyancy to aquatic microorganisms without acting as storage repositories.

Extrachromosomal DNA (Plasmids)

Small, double-stranded, non-chromosomal DNA molecules that replicate independently within bacterial cytoplasm.

R Plasmids

Plasmids bearing resistance genes that protect host bacteria against antimicrobial agents or toxins.

Virulence Plasmids

Plasmids encoding structures or toxins that enhance a pathogen's ability to cause host disease.

Col Plasmids

Plasmids encoding bacteriocins used by host bacteria to eliminate competing bacterial strains.

Hopanoids

Pentacyclic sterol-like lipid molecules present in bacterial plasma membranes that provide structural rigidity.

Passive Diffusion

Unassisted movement of nonpolar or small molecules (such as $H_2O$, $O_2$, and $CO_2$) across membranes down a concentration gradient without displaying saturation kinetics.

Facilitated Diffusion

Carrier-assisted movement of solutes across plasma membranes down a gradient via permeases, exhibiting saturation kinetics.

ABC Transporters

Primary active transport systems utilizing ATP binding and hydrolysis to import or export specific solutes via uniporter mechanisms.

Major Facilitator Superfamily (MFS)

Secondary active transport systems driven by ion gradients operating through symport or antiport mechanisms.

Group Translocation (PTS System)

An active transport process where incoming sugars are chemically modified via phosphorylation using phosphoenolpyruvate (PEP) as a high-energy donor.

Peptidoglycan (Murein)

A rigid mesh-like polymer of repeating disaccharides (NAM and NAG) cross-linked by amino acids forming the bacterial cell wall.

Diaminopimelic Acid (DAP)

An amino acid present in the peptide side-chains of peptidoglycan unique to Gram-negative bacteria such as Escherichia coli.

Lysozyme

An enzyme present in animal secretions that cleaves the $\text{beta-1,4-glycosidic bonds}$ between NAM and NAG in peptidoglycan.

Penicillin

An antibiotic that targets bacterial cell wall synthesis by inhibiting transpeptidase enzymes responsible for cross-linking peptidoglycan side chains.

Vancomycin

A glycopeptide antibiotic that binds terminal D-alanine residues to prevent peptidoglycan cross-linking.

Teichoic Acids

Negatively charged acidic polymers embedded exclusively within Gram-positive cell walls.

Lipopolysaccharide (LPS)

A complex glycolipid in the outer membrane of Gram-negative bacteria composed of Lipid A, core polysaccharide, and O antigen.

Lipid A

The hydrophobic anchor component of LPS that acts as an endotoxin, potentially causing endotoxic shock upon release into host bloodstreams.

O Antigen

The outermost polysaccharide chain of LPS that exhibits high strain variability, defining distinct serovar lineages.

Mycolic Acids

Complex waxy hydroxy lipids found in the cell walls of Mycobacterium species that necessitate acid-fast staining procedures.

Mycoplasma

A genus of small bacterial pathogens naturally lacking a cell wall and incorporating environmental sterols to stabilize plasma membranes.

L-form Bacteria

Bacterial variants that temporarily lose peptidoglycan cell walls under stress but retain the ability to regenerate them.

Capsule

A structured, non-washable polysaccharide outer layer that protects bacteria against phagocytosis, desiccation, and viruses.

Type IV Pili

Extracellular protein filaments responsible for twitching motility via rapid extension and retraction.

Endospore

A dormant, highly resistant structure formed inside certain Gram-positive bacteria (Bacillus, Clostridium) possessing a dehydrated core and calcium dipicolinate.

Ether Linkages

Chemical bonds linking branched isoprenoid side chains to glycerol backbones in archaeal plasma membranes.

Pseudomurein

A cell wall polysaccharide found in certain methanogenic archaea consisting of NAT and NAG linked by $\text{beta-1,3-glycosidic bonds}$.