Ch.4 Functional Anatomy of Prokaryotic and Eukaryotic Cells

Vocabulary flashcards covering prokaryotic and eukaryotic cellular anatomy, bacterial shapes and arrangements, cell wall structures, motility appendages, ribosomes, and endospores.

Prokaryote

An organism whose cells lack a distinct nucleus and membrane-bound organelles, coming from the Greek words for prenucleus.

Eukaryote

An organism whose cells contain a true nucleus enclosed in a nuclear membrane and membrane-bound organelles, coming from the Greek words for true nucleus.

Coccus

A spherical-shaped bacterial cell (plural: cocci, meaning berries).

Bacillus

A rod-shaped bacterial cell (plural: bacilli, meaning little rods or walking sticks).

Vibrio

A comma-shaped spiral bacterial cell with less than one complete turn or twist.

Spirillum

A spiral bacterial cell that is corkscrew-shaped and rigid.

Spirochete

A spiral bacterial cell that is helical and flexible, moving via axial filaments.

Diplococci

Cocci that divide and remain attached in pairs.

Streptococci

Cocci that divide and remain attached in chainlike patterns.

Staphylococci

Cocci that divide in multiple planes and form grapelike clusters or broad sheets.

Tetrads

Cocci that divide in two planes and remain in groups of four.

Sarcinae

Cocci that divide in three planes and remain in cubelike groups of eight.

Streptobacilli

Bacilli that remain attached in chains after division.

Coccobacilli

Oval bacterial cells that closely resemble spherical cocci.

Glycocalyx

A viscous, gelatinous polymer surrounding the cell wall, composed of polysaccharide, polypeptide, or both.

Capsule

An organized type of glycocalyx that is firmly attached to the cell wall and contributes to bacterial virulence.

Slime Layer

An unorganized and loosely attached type of glycocalyx surrounding a bacterial cell.

Extracellular Polymeric Substance (EPS)

A glycocalyx that helps cells in a biofilm attach to target environments and to each other.

Flagella

Long filamentous appendages external to the cell wall that propel bacteria, composed of the protein flagellin.

Atrichous

Bacteria that lack flagella (without projections).

Arrangements of Bacterial Flagella

Includes peritrichous (over entire cell), monotrichous (single polar), lophotrichous (tuft at one pole), and amphitrichous (at both poles).

Basal Body

The structural part of a flagellum consisting of a central rod and pairs of rings that anchors the flagellum to the cell wall and plasma membrane.

Taxis

The movement of a bacterium toward or away from a particular stimulus.

H Antigen

A flagellar protein useful for distinguishing among serovars (variations within a species) of gram-negative bacteria.

Axial Filaments

Bundles of fibrils (also called endoflagella) anchored at one end of a spirochete whose rotation causes corkscrew movement of the cell.

Fimbriae

Short, thin, hairlike appendages found in many gram-negative bacteria that enable adherence to surfaces, host tissues, or other cells to form biofilms.

Pili

Hairlike appendages longer than fimbriae, numbering one or two per cell, involved in twitching motility and DNA transfer.

Conjugation (Sex) Pili

Specialized pili that bring bacteria together to facilitate the transfer of DNA from one cell to another.

Peptidoglycan

A macromolecular network forming the bacterial cell wall, consisting of a repeating disaccharide connected by polypeptide cross-bridges.

N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM)

The two alternating monosaccharide units that form the disaccharide backbone of peptidoglycan.

Gram-Positive Cell Wall

A bacterial cell wall characteristically composed of many thick, rigid layers of peptidoglycan containing teichoic acids.

Gram-Negative Cell Wall

A bacterial cell wall containing a thin peptidoglycan layer situated in a periplasm, surrounded by an outer membrane composed of lipopolysaccharides, lipoproteins, and phospholipids.

Teichoic Acids

Negatively charged alcohol phosphate compounds in gram-positive cell walls that regulate cation movement and provide antigenic specificity.

Periplasm

The gel-like fluid in the periplasmic space between the outer membrane and plasma membrane of gram-negative bacteria, containing degradative enzymes and transport proteins.

Lipopolysaccharide (LPS)

A complex molecule in the gram-negative outer membrane consisting of O polysaccharide, core polysaccharide, and Lipid A.

Lipid A

The lipid portion of lipopolysaccharide embedded in the top layer of the outer membrane in gram-negative bacteria, acting as an endotoxin.

Porins

Proteins in the outer membrane of gram-negative bacteria that form channels permitting the passage of molecules.

Mycoplasma

A genus of bacteria that lack cell walls and possess unique sterols in their plasma membranes to protect against lysis.

Pseudomurein

A peptidoglycan-like substance found in archaeal cell walls that contains N-acetyltalosaminuronic acid instead of NAM and lacks d-amino acids.

Mycolic Acid

A hydrophobic waxy lipid present in high concentrations (60%) in the cell walls of acid-fast bacteria like Mycobacterium and Nocardia.

Plasmids

Small, circular extrachromosomal DNA molecules in bacteria that carry non-essential genes, such as those for antibiotic resistance or toxin production.

70S Ribosomes

Prokaryotic ribosomes composed of a 50S large subunit and a 30S small subunit, functioning in protein synthesis.

Svedberg Units (S)

Units expressing the rate of sedimentation of particles during centrifugation, reflecting size and density.

Endospores

Durable, highly resistant resting structures formed inside bacteria such as Bacillus and Clostridium when nutrients are depleted.

Sporulation

The process of endospore formation within a vegetative bacterial cell.

Germination

The process by which an endospore returns to an active vegetative state.

Microtubules

Protein tubes composed of tubulin organized in a 9 + 2 array in eukaryotic flagella and cilia.

80S Ribosomes

Eukaryotic ribosomes composed of a 60S large subunit and a 40S small subunit, found free in cytoplasm or bound to endoplasmic reticulum.

Cristae

Infoldings of the inner membrane of mitochondria that house cellular respiration machinery.

Matrix

The fluid-filled inner cavity enclosed by the inner membrane of a mitochondrion.