Chapter 4: Functional Anatomy of Prokaryotic and Eukaryotic Cells

Prokaryotic Cell

Cell with no membrane-bound nucleus and no membrane-bound organelles.

Eukaryotic Cell

Cell with chromosomes inside a membrane-bound nucleus and membrane-bound organelles.

Prokaryotic Chromosome

Usually one circular chromosome that is not enclosed by a membrane.

Eukaryotic Chromosomes

Chromosomes located inside a membrane-bound nucleus.

Prokaryotic Cell Division

Prokaryotic cells divide by binary fission.

Eukaryotic Cell Division

Eukaryotic cells divide by mitosis.

Bacterial Cell Wall

Bacterial cell wall containing peptidoglycan that protects the cell.

Monomorphic Bacteria

Bacteria that normally maintain one basic shape.

Bacillus Shape

Rod-shaped bacterium.

Coccus Shape

Spherical or round bacterium.

Vibrio

Curved rod-shaped bacterium.

Spirillum

Spiral or corkscrew-shaped bacterium.

Spirochete

Slender flexible helical bacterium that moves with a corkscrew motion.

Diplo Prefix

Indicates bacteria arranged in pairs.

Diplococci

Pairs of spherical bacterial cells.

Diplobacilli

Pairs of rod-shaped bacterial cells.

Strepto Prefix

Indicates bacteria arranged in chains.

Streptococci

Chains of spherical bacterial cells.

Streptobacilli

Chains of rod-shaped bacterial cells.

Staphylo Prefix

Indicates bacteria arranged in clusters.

Staphylococci

Clusters of spherical bacterial cells.

Tetrads

Groups of four cocci.

Sarcinae

Packets of cocci commonly arranged in groups of eight.

Bacillus vs bacillus

Capitalized Bacillus can be a genus name while lowercase bacillus describes a rod shape.

Structures Found in All Bacteria

Cytoplasm; plasma membrane; 70S ribosomes; and a nucleoid containing DNA.

Glycocalyx

Viscous gelatinous material located outside the bacterial cell wall.

Glycocalyx Composition

Made of polysaccharide and or polypeptide.

Capsule

Organized glycocalyx that is firmly attached to the bacterial cell.

Slime Layer

Unorganized glycocalyx that is loosely attached to the bacterial cell.

Capsule vs Slime Layer

Capsule is organized and firmly attached while slime layer is unorganized and loose.

Flagella

Filamentous appendages that propel bacterial cells.

Taxis

Movement of a bacterium toward or away from a stimulus.

Bacterial Flagellum Structure

Consists of a filament; hook; and basal body.

Flagellar Filament

Long external portion of a bacterial flagellum.

Flagellar Hook

Short connecting region between the filament and basal body that helps rotation.

Basal Body

Structure that anchors a bacterial flagellum to the cell.

Monotrichous Flagella

One flagellum located at one end of a bacterial cell.

Lophotrichous Flagella

Multiple flagella located at one end of a bacterial cell.

Amphitrichous Flagella

Flagella located at both ends of a bacterial cell.

Peritrichous Flagella

Flagella distributed around the entire bacterial cell.

Axial Filaments

Structures in spirochetes whose rotation produces corkscrew movement.

Fimbriae

Hairlike bacterial appendages mainly used for attachment.

Pili

Bacterial appendages involved in motility or DNA transfer.

Conjugation Pilus

Pilus involved in transferring DNA from one bacterial cell to another.

Fimbriae vs Pili

Fimbriae mainly provide attachment while pili can provide motility or DNA transfer.

Cell Wall Function

Protects the plasma membrane and helps prevent osmotic lysis.

Peptidoglycan

Strong structural polymer found in bacterial cell walls.

NAG

N-acetylglucosamine; one of the repeating sugars in peptidoglycan.

NAM

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

Peptidoglycan Structure

Alternating NAG and NAM rows linked together by polypeptides.

Gram-Positive Cell Wall

Cell wall containing a thick layer of peptidoglycan.

Gram-Negative Cell Wall

Cell wall with thin peptidoglycan; an outer membrane; and a periplasmic space.

Gram-Negative Outer Membrane

Additional membrane that helps protect bacteria from phagocytes and antibiotics.

Periplasmic Space

Space associated with the cell envelope of Gram-negative bacteria.

Lipopolysaccharide (LPS)

Major molecule found in the outer membrane of Gram-negative bacteria.

Lipid A

Portion of Gram-negative LPS that acts as an endotoxin.

Endotoxin

Toxic bacterial component associated with lipid A of Gram-negative bacteria.

Gram Stain

Staining method that distinguishes Gram-positive and Gram-negative bacteria by cell wall differences.

Gram-Positive Stain Result

Gram-positive bacteria appear purple after Gram staining.

Gram-Negative Stain Result

Gram-negative bacteria appear pink or red after Gram staining.

Gram-Positive vs Gram-Negative

Gram-positive has thick peptidoglycan while Gram-negative has thin peptidoglycan and an outer membrane.

Acid-Fast Cell Wall

Cell wall containing a waxy lipid called mycolic acid attached to peptidoglycan.

Mycolic Acid

Waxy lipid found in acid-fast bacterial cell walls.

Mycobacterium

Genus associated with acid-fast cell walls containing mycolic acid.

Acid-Fast Stain

Staining method used to identify bacteria with acid-fast cell walls.

Mycoplasmas

Bacteria that lack cell walls.

Plasma Membrane

Phospholipid bilayer that encloses the cytoplasm.

Peripheral Membrane Proteins

Proteins located on the surface of the plasma membrane.

Integral Membrane Proteins

Proteins embedded within the plasma membrane.

Transmembrane Proteins

Integral proteins that extend through the plasma membrane.

Fluid Mosaic Model

Model describing the membrane as flexible with moving phospholipids and proteins.

Plasma Membrane Movement

Membrane proteins can move while phospholipids rotate and move laterally.

Selective Permeability

Ability of a membrane to allow some substances through while blocking others.

Passive Transport

Movement from high concentration to low concentration without cellular energy.

Active Transport

Movement against the concentration gradient that requires energy.

Concentration Gradient

Difference in the concentration of a substance between two areas.

Moving Down a Concentration Gradient

Movement from high concentration to low concentration.

Moving Against a Concentration Gradient

Movement from low concentration to high concentration.

Simple Diffusion

Passive movement of a solute from high concentration to low concentration.

Equilibrium

State in which molecules are evenly distributed with no net concentration change.

Facilitated Diffusion

Passive movement from high to low concentration using a membrane transporter protein.

Simple vs Facilitated Diffusion

Both move high to low without ATP but facilitated diffusion requires a transporter protein.

Osmosis

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

Aquaporins

Protein channels that allow water to move across membranes.

Osmotic Pressure

Pressure required to stop the movement of water across a membrane.

Isotonic Solution

Solution with equal solute concentrations inside and outside the cell.

Isotonic Water Movement

Water moves in and out equally with no net movement.

Hypotonic Solution

Solution with lower solute concentration outside the cell than inside.

Hypotonic Water Movement

Water moves into the cell.

Hypotonic Cell Effect

Cell swells as water enters and may undergo osmotic lysis if the wall is weak or damaged.

Osmotic Lysis

Bursting of a cell caused by excessive water entering the cell.

Hypertonic Solution

Solution with higher solute concentration outside the cell than inside.

Hypertonic Water Movement

Water moves out of the cell.

Hypertonic Cell Effect

Cell loses water and its cytoplasm shrinks.

Plasmolysis

Shrinking of the cytoplasm that causes the plasma membrane to pull away from the cell wall.

Isotonic vs Hypotonic vs Hypertonic

Isotonic has no net water movement; hypotonic moves water in; hypertonic moves water out.

Active Transport Requirements

Requires a transporter protein and ATP.

Active Transport Direction

Moves substances from low concentration to high concentration against the gradient.

Cytoplasm

Substance located inside the plasma membrane.

Nucleoid

Non-membrane-bound region of a prokaryotic cell containing the bacterial chromosome.