Prokaryotic Cells Flashcards

Vocabulary flashcards covering prokaryotic cell structures, morphology, cell wall types, transportation mechanisms, cellular appendages, and endospores based on Chapter 3.

Monomorphic

Having a single, constant cellular shape.

Pleomorphic

Having the ability to take on multiple cellular forms or shapes.

Bacilli

Rod-shaped bacterial cells.

Cocci

Spherical bacterial cells.

Spirochetes

Spiral-shaped bacterial cells that move using a corkscrew motion.

Diplococci

Paired spherical bacterial cells resulting from cell division.

Streptococci

Chains of spherical bacterial cells.

Staphylococci

Grapelike clusters of spherical bacterial cells.

Diplobacilli

Paired rod-shaped bacterial cells.

Streptobacilli

Chains of rod-shaped bacterial cells.

Binary Fission

An asexual reproduction process in prokaryotes where DNA replication occurs, the cell elongates, a septum forms, and the cell partitions into two identical daughter cells.

Plasma Membrane

A selectively permeable fluid mosaic phospholipid bilayer that surrounds the cell, serves as the main point of interaction with the environment, produces ATP, and contains receptors.

Peptidoglycan

A core mesh-like component of bacterial cell walls composed of glycan chains of alternating N-acetyl-D-glucosamine (NAG) and N-acetylmuramic acid (NAM) residues connected by peptide cross-links.

Gram-Negative Cell Wall

A bacterial cell wall structure containing a thin peptidoglycan layer ($10\text{--}20\text{\%}$ of wall), an outer membrane with lipopolysaccharide (LPS) and Lipid A, porins, and a periplasmic space; stains pink.

Gram-Positive Cell Wall

A bacterial cell wall structure containing a thick peptidoglycan layer ($70\text{--}80\text{\%}$ of wall) and teichoic acids, lacking an outer membrane; stains purple.

Lipid A

An endotoxin component found within the lipopolysaccharide (LPS) layer of the Gram-negative bacterial outer membrane.

Teichoic Acid

Acidic polymers found in Gram-positive cell walls that help stabilize the thick peptidoglycan cell wall structure.

Mycolic Acid

A waxy lipid substance present in acid-fast cell walls that restricts the passage of drugs, nutrients, and gases.

Mycoplasmas

Bacteria that naturally lack a cell wall, possess a sterol-enriched plasma membrane, and are highly pleomorphic.

L-Forms

Bacteria that previously possessed a cell wall but lost it, contributing to persistent infections and resistance to environmental stresses like boiling and autoclaving.

Simple Diffusion

Passive transport movement of small molecules, gases, and lipid-soluble substances across a membrane from an area of higher concentration to lower concentration without energy input.

Facilitated Diffusion

Passive movement of ions and larger substances down their concentration gradient using specific membrane transport proteins without requiring cellular energy.

Osmosis

The passive net movement of water across a selectively permeable membrane from an area of higher water (lower solute) concentration to lower water (higher solute) concentration.

Active Transport

Energy-requiring movement of substances across a membrane against their concentration gradient from an area of low concentration to high concentration using transport proteins.

Chemotaxis

Movement of a cell in response to a chemical stimulus.

Phototaxis

Movement of a cell in response to light signals.

Monotrichous

Describing a bacterial cell that has a single flagellum.

Lophotrichous

Describing a bacterial cell that has a tuft or cluster of flagella located at one end.

Amphitrichous

Describing a bacterial cell that has flagella located at both ends of the cell.

Peritrichous

Describing a bacterial cell that has flagella distributed across its entire outer surface.

Periplasmic Flagella (Axial Filaments)

Flagellar fibers located within the periplasmic space between the plasma membrane and cell wall that allow spirochetes to move in a characteristic corkscrew motion.

Fimbriae

Short, bristle-like protein surface structures that allow prokaryotes to adhere to surfaces or each other to establish biofilms.

Pili

Rigid, hair-like protein structures on bacterial surfaces that are longer and less numerous than fimbriae, involved in motility and conjugation.

Glycocalyx

A sticky, carbohydrate-enriched outer layer that promotes adhesion to host tissues and surfaces, offering protection against antibiotics and disinfection.

Slime Layer

An unorganized, loosely associated type of glycocalyx that is easily rinsed away from the bacterial cell surface.

Capsule

A well-organized, tightly attached glycocalyx structure that acts as a virulence factor by protecting cells against phagocytosis.

Nucleoid

The region in the cytoplasm of a prokaryotic cell where the single, circular double-stranded DNA chromosome is located.

70S Ribosome

The complete prokaryotic ribosome responsible for protein synthesis, composed of a $50\text{S}$ large subunit and a $30\text{S}$ small subunit.

Inclusion Bodies

Cytoplasmic storage structures within prokaryotic cells that store nutrients or specialized inclusions like carboxysomes and magnetosomes.

Endospores

Dormant, highly resistant structures formed by specific bacterial genera (such as Bacillus, Clostridium, and Clostridioides) to survive extreme environmental stresses.

Sporulation

The multi-step process by which a vegetative bacterial cell forms a dormant endospore in response to environmental stress.