Chapter 4 | Functional Anatomy of Prokaryotic and Eukaryotic Cells

Prokaryote

Cell lacking a membrane-bound nucleus; term means "prenucleus"

Eukaryote

Cell with a true membrane-bound nucleus; term means "true nucleus"

Binary fission

Asexual reproduction method used by prokaryotic cells

Monomorphic

Bacteria having a single, consistent shape

Pleomorphic

Bacteria capable of assuming several different shapes

Coccus

Spherical-shaped bacterial cell

Bacillus

Rod-shaped bacterial cell

Vibrio

Curved, comma-shaped rod bacterium

Spirillum

Rigid, helical-shaped bacterium

Spirochete

Flexible, helical bacterium that moves via axial filaments

Diplococci

Bacterial arrangement in pairs of cocci

Streptococci

Bacterial arrangement in chains of cocci

Staphylococci

Bacterial arrangement in clusters of cocci

Tetrads

Bacterial arrangement in groups of four

Sarcinae

Bacterial arrangement in cubelike groups of eight

Glycocalyx

Gelatinous polysaccharide/polypeptide covering external to the cell wall

Capsule

Neatly organized, firmly attached glycocalyx; protects against phagocytosis

Slime layer

Unorganized, loosely attached glycocalyx

Flagellin

Protein that makes up bacterial flagella

Flagellum filament

Outermost region of the flagellum

Flagellum hook

Structure attaching the filament to the basal body

Basal body

Flagellum structure anchoring it to the cell wall and membrane

Taxis

Movement of a motile bacterium toward or away from a stimulus

Positive taxis

Movement toward an attractant

Negative taxis

Movement away from a repellent

H antigen

Antigen formed by flagellar protein; used in bacterial serotyping

Axial filament

Endoflagellum wrapped around a spirochete cell, enabling motility

Fimbriae

Short hairlike appendages that allow bacterial attachment to surfaces

Pili

Longer appendages involved in twitching/gliding motility and DNA transfer

Conjugation

DNA transfer between bacterial cells via pili

Peptidoglycan

Polymer of NAG and NAM cross-linked by peptides; forms the bacterial cell wall

NAG

N-acetylglucosamine; sugar subunit of peptidoglycan

NAM

N-acetylmuramic acid; sugar subunit of peptidoglycan

Teichoic acid

Negatively charged polymer in Gram-positive cell walls that regulates cations

Lipoteichoic acid

Teichoic acid that anchors the cell wall to the plasma membrane

Wall teichoic acid

Teichoic acid that links to the peptidoglycan layer

Periplasmic space

Region between the outer membrane and plasma membrane in Gram-negative bacteria

Outer membrane

Lipopolysaccharide-containing membrane found only in Gram-negative bacteria

Lipopolysaccharide (LPS)

Outer membrane component made of O polysaccharide and Lipid A

O polysaccharide

Sugar component of LPS that functions as an antigen

Lipid A

Endotoxin component of the Gram-negative outer membrane

Porins

Proteins forming channels through the outer membrane for small molecules

Gram-positive cell wall

Thick peptidoglycan layer with teichoic acids, no outer membrane

Gram-negative cell wall

Thin peptidoglycan layer with an outer membrane and periplasmic space

Gram stain decolorization step

Alcohol step that dehydrates Gram-positive walls but dissolves Gram-negative outer membranes

Mycoplasma

Bacterial genus that naturally lacks a cell wall; has sterols in its membrane

Pseudomurein

Cell wall polymer found in Archaea, lacking NAM and D-amino acids

Acid-fast cell wall

Wall containing mycolic acid over a thin peptidoglycan layer

Protoplast

Gram-positive cell remnant after lysozyme fully destroys the cell wall

Spheroplast

Gram-negative cell remnant after lysozyme partially destroys the cell wall

L forms

Bacteria that survive without producing a cell wall

Penicillin mechanism

Antibiotic that interferes with peptidoglycan (cell wall) synthesis

Fluid mosaic model

Model describing the plasma membrane as a dynamic phospholipid bilayer with mobile proteins

Peripheral proteins

Membrane proteins located on the membrane surface

Integral proteins

Membrane proteins that penetrate through the membrane

Mesosome

Irregular infolding of the plasma membrane; considered an artifact, not a true structure

Simple diffusion

Passive movement of molecules from high to low concentration until equilibrium

Facilitated diffusion

Passive transport of substances via a transporter protein, following the gradient

Osmosis

Movement of water across a selectively permeable membrane from high to low water concentration

Osmotic pressure

Pressure required to stop the osmotic movement of water

Isotonic solution

Solution with equal solute concentration inside and outside the cell

Hypotonic solution

Solution with lower solute concentration outside the cell; water moves into the cell

Hypertonic solution

Solution with higher solute concentration outside the cell; water moves out of the cell

Active transport

Transport of substances against the concentration gradient using a transporter protein and ATP

Group translocation

Active transport process that chemically alters a substance as it crosses the membrane, using PEP

Nucleoid

Region containing the bacterial chromosome

Plasmid

Small circular extrachromosomal DNA molecule carrying non-essential genes

70S ribosome

Ribosome type found in prokaryotes and in mitochondria/chloroplasts; composed of 50S and 30S subunits

Metachromatic granules

Bacterial inclusion storing inorganic phosphate

Polysaccharide granules

Bacterial inclusion storing glycogen or starch

Carboxysomes

Bacterial inclusion containing ribulose 1,5-diphosphate carboxylase for CO2 fixation

Magnetosomes

Bacterial inclusion containing Fe3O4 (iron oxide)

Endospore

Highly resistant dormant structure formed by some bacteria under adverse conditions

Cilia

Numerous, short cell surface projections used for motility or moving substances

Chitin

Carbohydrate composing fungal cell walls

Glucan and mannan

Carbohydrates composing yeast cell walls

Cellulose

Carbohydrate composing plant and algal cell walls

Phagocytosis

Endocytosis process where pseudopods engulf particles

Pinocytosis

Endocytosis process where the membrane folds inward to bring in fluid

Cytoplasmic streaming

Movement of cytoplasm throughout a eukaryotic cell

80S ribosome

Ribosome type found in eukaryotic cytoplasm and rough ER; composed of 60S and 40S subunits

Nucleus

Double-membrane organelle containing the cell's DNA as chromatin

Chromatin

Complex of DNA and histone proteins in the eukaryotic nucleus

Rough endoplasmic reticulum

ER studded with ribosomes; site of protein synthesis

Smooth endoplasmic reticulum

ER lacking ribosomes; synthesizes lipids, membranes, and hormones

Golgi complex

Organelle that modifies and packages proteins from the ER for secretion

Lysosome

Organelle formed from the Golgi complex that stores digestive enzymes

Vacuole

Membrane-enclosed storage organelle, common in plant cells

Mitochondria

Double-membrane organelle with cristae and matrix; primary site of ATP production

Cristae

Inner folds of the mitochondrial membrane

Chloroplast

Organelle containing thylakoids and chlorophyll; site of photosynthesis

Thylakoid

Flattened membrane structure inside chloroplasts containing chlorophyll

Peroxisome

Organelle that oxidizes organic compounds and neutralizes H2O2 via catalase

Catalase

Enzyme in peroxisomes that destroys hydrogen peroxide

Centrosome

Organelle composed of pericentriolar material and centrioles; forms the mitotic spindle

Centriole

Structure made of 9 triplet microtubules involved in spindle formation

Endosymbiotic theory

Theory that eukaryotic organelles evolved from engulfed prokaryotic cells

Endosymbiotic evidence

Mitochondria and chloroplasts share prokaryote-like traits: own DNA, 70S ribosomes, binary fission