Functional Anatomy of Prokaryotic and Eukaryotic Cells (Chapter 4)

Vocabulary flashcards covering key concepts from Prokaryotic and Eukaryotic cell structure, walls, membranes, organelles, and related processes from the lecture notes.

Prokaryote

An organism whose cells lack a true nucleus and membrane-bound organelles; typically has a single circular chromosome and divides by binary fission.

Eukaryote

An organism whose cells contain a true nucleus enclosed by a nuclear membrane, histones, organelles, and (when present) polysaccharide cell walls; divides by mitosis.

Nucleoid

Region in prokaryotic cells where the chromosome is located; not enclosed by a membrane and usually contains a single circular chromosome.

Histone

Protein around which eukaryotic DNA is wound; not present in most prokaryotes.

Peptidoglycan

Bacterial cell wall polymer of sugars and amino acids; cross-bridges are disrupted by penicillin.

Glycocalyx

External, sticky layer made of polysaccharide and/or polypeptide; contributes to virulence and biofilm formation.

Capsule

A neatly organized and firmly attached glycocalyx that helps prevent phagocytosis and aids adhesion.

Slime layer

An unorganized, loosely attached glycocalyx that aids adhesion and protects cells.

Flagellum

Long, filamentous organelle used for motility; composed of flagellin and consisting of filament, hook, and basal body.

Filament

The long, outermost part of the flagellum; extends from the cell.

Hook

Connector between the flagellar filament and the basal body.

Basal body

Anchors the flagellum in the cell wall/membrane and contains rings that rotate to drive motion.

H antigen

Flagellar protein antigen used to differentiate serovars (e.g., E. coli O157:H7).

Archaella

Motility structures in Archaea that rotate like flagella and are powered by ATP.

Archaellin

Protein that composes the archaellum in Archaea.

Axial filament (endoflagellum)

Motility structure of spirochetes, located at one end; rotation causes corkscrew movement.

Fimbriae

Hairlike appendages that enable attachment and biofilm formation.

Pili

Longer appendages used for attachment, DNA transfer (conjugation pili), and some forms of motility.

Bacterial cell wall

Rigid outer layer primarily composed of peptidoglycan; differences in structure contribute to Gram staining results.

Gram-positive cell wall

Thick, multi-layered peptidoglycan with teichoic/lipoteichoic acids; high susceptibility to penicillin.

Gram-negative cell wall

Thin peptidoglycan layer with an outer membrane containing LPS; periplasmic space; lower penicillin susceptibility.

Lipopolysaccharide (LPS)

Outer membrane component of Gram-negative bacteria; includes O antigen and lipid A (endotoxin).

NAG

N-acetylglucosamine; part of the peptidoglycan disaccharide unit.

NAM

N-acetylmuramic acid; part of the peptidoglycan disaccharide unit.

Penicillin

Antibiotic that inhibits peptide cross-bridges in peptidoglycan, weakening the cell wall.

Lysozyme

Enzyme that hydrolyzes bonds in the glycan portion of peptidoglycan.

Porin

Channel-forming proteins in the outer membrane of Gram-negative bacteria that allow molecule passage.

Gram stain mechanism

Crystal violet-iodine is retained by thick peptidoglycan in Gram-positive cells; Gram-negative cells are decolorized and counterstained with safranin.

Teichoic acids

Negatively charged polymers in Gram-positive walls that regulate cation movement and provide antigenic specificity.

Acid-fast cell walls

Waxy, mycolic-acid-containing walls (e.g., Mycobacterium) that retain carbolfuchsin stain despite acid-alcohol decolorization.

Mycoplasmas

Bacteria that lack a cell wall and have sterols in their membranes for protection.

Pseudomurein

Archaeal cell wall component similar to peptidoglycan but lacking NAM and D-amino acids.

L forms

Wall-less bacterial forms that can swell and assume irregular shapes; susceptible to osmotic lysis.

Protoplast

Wall-less Gram-positive cell.

Spheroplast

Wall-less Gram-negative cell.

Plasma (cytoplasmic) membrane

Phospholipid bilayer surrounding the cytoplasm; contains integral and peripheral proteins; fluid mosaic model.

Simple diffusion

Movement of solutes across the membrane without membrane proteins down the concentration gradient.

Facilitated diffusion

Passive transport via membrane channels or carriers; specific or nonspecific; along the concentration gradient.

Osmosis

Net movement of water across a selectively permeable membrane from higher to lower water concentration; may involve aquaporins.

Isotonic solution

Solute concentration is equal inside and outside the cell; no net water movement.

Hypotonic solution

Lower solute outside the cell; water influx causes cell swelling.

Hypertonic solution

Higher solute outside the cell; water efflux causes cell shrinkage.

Active transport

Transport against a concentration gradient using transporter proteins and ATP.

Group translocation

Active transport where the substance is chemically altered as it crosses the membrane; uses PEP.

Cytoplasm

Contents inside the cell membrane but outside the nucleus; includes cytosol, ribosomes, inclusions, and cytoskeleton.

Nucleoid

Region containing the bacterial chromosome; not membrane-bound.

Plasmid

Small extrachromosomal DNA circles carrying nonessential genes; replicate independently and can transfer between bacteria.

Ribosome (prokaryotic)

70S ribosome composed of 50S and 30S subunits; site of protein synthesis; targets of several antibiotics.

Endospore

Resting, highly resistant dormant cell produced by Bacillus and Clostridium; formed via sporulation; germinates back to vegetative cell.

Mitochondria

Double-membrane organelles with cristae; site of cellular respiration; contain 70S ribosomes and circular DNA; replicate independently.

Chloroplasts

Organelle of photosynthesis in plants/algae; contain thylakoids with chlorophyll; have 70S ribosomes and circular DNA.

Endoplasmic reticulum (ER)

Membrane network; rough ER has ribosomes for protein synthesis; smooth ER synthesizes lipids and membranes.

Golgi complex

Modifies and packages proteins from the ER; secretes proteins via secretory vesicles.

Lysosome

Vesicles containing digestive enzymes for macromolecule breakdown.

Vacuole

Storage organelle; formed from Golgi; involved in endocytosis and maintaining cell shape.

Peroxisome

Organelle that oxidizes fatty acids and detoxifies harmful substances.

Centrosome

Organizing center for the mitotic spindle; contains pericentriolar matrix and centrioles.

Nucleus

Double-membrane organelle enclosing the cell’s DNA; chromatin formed with histones; chromosomes condense during mitosis/meiosis.

The evolution of eukaryotes

Endosymbiotic theory posits that mitochondria and chloroplasts originated from engulfed bacteria; supported by circular DNA, 70S ribosomes, and double membranes.

9 + 2 arrangement

Structure of eukaryotic flagella and cilia: nine outer pairs of microtubules surrounding two central ones, enabling wave-like movement.

Endocytosis

Process by which cells engulf external material via membrane vesicles; includes phagocytosis, pinocytosis, and receptor-mediated endocytosis.