MICROB 3200 Cell Structure and Function Vocabulary

Vocabulary flashcards covering key bacterial cell structures, envelopes, cytoskeleton proteins, morphology, and appendages from the MICROB 3200 Cell Structure and Function lecture.

Prokaryote

A unicellular organism with a nucleoid and no membrane-bound organelles.

Taxonomy

Classification of organisms largely based on evolutionary relationships, genetics, and shared ancestry.

Cell envelope

The multilayered barrier surrounding the bacterial cytoplasm that protects the bacterium from environmental assaults.

Cell wall

A rigid outer shell that protects the cell from osmotic stresses.

Cell membrane

A lipid, hydrophobic barrier containing proteins; contains the cytoplasm, mediates transport, and scaffolds cellular activities.

Cytoplasm

Gel-like network containing proteins, DNA, RNA, cytoskeletal-like elements, etc.

Nucleoid

Region containing bacterial DNA, expression machinery, DNA-binding proteins, and regulatory proteins.

Origin of replication

Central point associated with the organized loops of bacterial chromosomal DNA.

FtsZ

Cytoskeletal protein that polymerizes to form the Z-ring; involved in maintaining cell diameter.

Z-ring

Ring formed by polymerized FtsZ.

MreB

Cytoskeletal protein required for elongation of rod-shaped cells.

CreS (crescentin)

Shape-determining protein in crescent-shaped cells that polymerizes along the inner curve.

Endospore

A dormant, tough, non-reproductive structure that allows bacteria to survive harsh environmental conditions.

Clostridium botulinum

Gram-positive, rod-shaped, anaerobic, spore-forming, motile bacterium that produces a neurotoxin causing botulism.

Clostridium tetani

Gram-positive, rod-shaped, anaerobic, spore-forming, motile bacterium producing a neurotoxin causing tetanus.

Phospholipid

Molecule consisting of glycerol linked to two fatty acids and a phosphoryl polar head group.

Sacculus

Another name for the bacterial cell wall; a single-molecule cage-like structure surrounding the cell membrane.

Peptidoglycan (PG)

Cage-like cell-wall polymer surrounding the membrane and protecting bacteria from environmental stresses.

NAG

N-acetylglucosamine, one of the two repeating sugars in peptidoglycan.

NAM

N-acetylmuramic acid, one of the two repeating sugars in peptidoglycan.

Mycoplasma pneumoniae

Very small free-living bacterium associated with respiratory infections that lacks a cell wall and peptidoglycan.

Coccus

Spherical bacterial morphology.

Bacillus/rod

Rod-shaped bacterial morphology.

Vibrio

Curved bacterial morphology.

Spirochete

Spiral/corkscrew-like bacterial morphology.

Diplococcus

Cocci arranged in pairs.

Gram-positive envelope

Relatively simple bacterial envelope containing thick peptidoglycan and teichoic acids, with no outer membrane and no LPS.

Gram-negative envelope

Relatively complex bacterial envelope containing thin peptidoglycan, no wall teichoic acids, an outer membrane, and LPS.

LPS

Lipopolysaccharide, a component of the Gram-negative outer membrane; also called endotoxin.

O antigen

Repeating pattern of highly variable sugars in LPS; each bacterial species has a unique O antigen.

LPS core

Component of LPS that is highly conserved in Gram-negative bacteria and forms a barrier against detergents.

Lipid A

Highly hydrophobic portion that anchors LPS to the outer membrane.

Porins

Channels in the Gram-negative outer membrane that allow facilitated diffusion of small hydrophilic molecules into the periplasm.

Differential stain

A stain used to distinguish different bacterial groups; the Gram stain distinguishes Gram-positive and Gram-negative bacteria.

Mycomembrane

Specialized membrane of Mycobacterium tuberculosis that is distinct from the outer membrane of classical Gram-negative bacteria.

Capsule

Anchored extracellular layer, mainly composed of polysaccharides.

Slime layer

Loose extracellular layer, mainly composed of polysaccharides.

Flagellum

Long, whip-like helical propeller that drives bacterial movement.

Pilus / fimbria

Hair-like cell-surface appendage found on many bacteria and archaea.

Sex pilus

Specialized pilus capable of transferring DNA between bacterial cells.