Ch4 P+1 & P+2: Prokaryote Structures and Bacterial Cell Walls

Vocabulary-style flashcards covering key concepts from Prokaryote Structures and Bacterial Cell Walls, including differences between eukaryotes and prokaryotes, glycocalyx, virulence factors, motility structures, genetic elements, ribosomes, cytoplasm, cell wall composition, Gram staining components, and endospore formation.

Eukaryote

Organisms with paired chromosomes in a nuclear membrane; histones; membrane-bound organelles; polysaccharide cell walls when present; divides by mitosis.

Prokaryote

Organisms with a single circular chromosome not enclosed by a membrane; no histones or organelles; divides by binary fission; bacteria have peptidoglycan cell walls; archaea have pseudomurein.

Nuclear membrane

Membrane surrounding the nucleus with pores; separates DNA from cytoplasm in eukaryotes.

Glycocalyx

External, viscous layer outside the cell wall made of polysaccharide and/or polypeptide; two types: capsule and slime layer.

Capsule

Neatly organized, firmly attached glycocalyx that can enhance virulence and protect against phagocytosis.

Slime layer

Unorganized, loose glycocalyx that can aid in adherence and biofilm formation.

Virulence

Severity or harmfulness of a disease; factors like capsules can increase virulence by helping evade the immune system.

Biofilm

A structured community of microorganisms embedded in a self-produced matrix attached to a surface; increased resistance to antibiotics.

Flagellum (Flagella)

Motility organelle; rotates to enable run/tumble; H antigens differentiate serovars.

H antigen

Flagellar antigen used to distinguish certain bacterial serovars (e.g., E. coli O157:H7).

Serovar

A group of closely related microorganisms distinguished by a characteristic set of antigens.

Fimbriae

Hair-like appendages used for attachment to surfaces.

Pili

Longer hair-like appendages involved in motility (gliding, twitching) and DNA transfer.

Conjugation pili

Pili that mediate DNA transfer between bacteria.

Nucleoid

Region containing the bacterial chromosome; circular chromosomal DNA.

Plasmid

Extrachromosomal DNA elements carrying non-essential genes (e.g., antibiotic resistance, toxins).

Ribosome

Protein-synthesizing organelles; in prokaryotes, 70S (subunits 50S and 30S).

Cytoplasm

Fluid inside the plasma membrane; ~80% water with enzymes, nutrients, and ions.

Cytoskeleton

Network of protein filaments providing shape and internal organization in bacteria.

Cell wall

Rigid layer that prevents osmotic lysis and contributes to pathogenicity; made of peptidoglycan in bacteria.

Peptidoglycan

Polymer of repeating disaccharides (NAG and NAM) cross-linked by polypeptides.

N-acetylglucosamine (NAG)

One sugar unit in the peptidoglycan disaccharide.

N-acetylmuramic acid (NAM)

The second sugar unit in the peptidoglycan disaccharide.

Gram-positive cell wall

Thick peptidoglycan layer with teichoic acids and lipoteichoic acid; negative charge; may aid attachment and antigenic specificity.

Teichoic acid

Polymers in Gram-positive cell walls contributing to charge and rigidity; includes wall teichoic acid.

Lipoteichoic acid

Teichoic acid anchored to the plasma membrane in Gram-positive cells.

Gram-negative cell wall

Thinner peptidoglycan layer and an outer membrane with LPS; contains porins and lipid A.

Lipopolysaccharide (LPS)

Outer membrane component of Gram-negative bacteria; contains O polysaccharide, lipid A (endotoxin).

O polysaccharide

O antigen part of LPS; used for antigenic serotyping.

Lipid A

Endotoxin component of LPS; release can trigger sepsis.

Porins

Protein channels in the outer membrane of Gram-negative bacteria for passage of molecules.

Endospore

Dormant, highly resistant structure produced under hostile conditions (e.g., nutrient depletion).

Sporulation

Formation of endospores in response to stress.

Germination

Return of an endospore to its vegetative, metabolically active state.