ch 3

Study Guide - Smart Notes

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Prokaryotic and eukaryotic cells differ in their structural complexity and the presence of membrane-bound organelles.

Prokaryotic cells: Small, simple cells lacking a nucleus and most membrane-bound organelles. Found in Bacteria and Archaea.
Eukaryotic cells: Larger, more complex cells with a nucleus and various membrane-bound organelles. Found in plants, animals, fungi, and protists.

Glycocalyx:
- Structure: Complex polysaccharide layer surrounding the outside of the cell.
- Function: Protects from dehydration, aids in adhesion, biofilm formation, and camouflage.
Capsule:
- Structure: Tighter, more ordered glycocalyx.
- Function: Adhesion, camouflage, anti-phagocytic properties.
Slime Layer:
- Structure: Loose, watery, and sticky glycocalyx.
- Function: Protects from dehydration, adhesion, biofilm formation, camouflage.
Flagella:
- Structure: Long, tail-like structure composed of a filament, hook, and basal body.
- Function: Motility; allows bacteria to move.
Fimbriae:
- Structure: Short, protein bristle-like projections, usually shorter than flagella.
- Function: Adhesion to surfaces and other cells; important in colonization.
Pili:
- Structure: Hollow tubes, usually longer than fimbriae but shorter than flagella.
- Function: Transfer of DNA between cells (conjugation); also aids in movement across surfaces.

Peptidoglycan:
- Structure: Rigid mesh of polysaccharide and protein.
- Function: Provides structural support and shape to the cell.
Gram Positive Cell Wall:
- Structure: Thick peptidoglycan layer, teichoic acids, lipoproteins, periplasmic space, inner plasma membrane.
- Function: Maintains cell shape, protects from osmotic lysis.
Gram Negative Cell Wall:
- Structure: Outer cell membrane, thin peptidoglycan layer, LPS in outer membrane, porins, lipoproteins, periplasmic space, inner plasma membrane.
- Function: Additional protection, selective permeability, and resistance to certain antibiotics.
Teichoic and Lipoteichoic Acids:
- Structure: Wall teichoic acids touch cell membrane; lipoteichoic acids do not. Only in gram positive cells.
- Function: Involved in cell wall maintenance and ion transport.
Porins:
- Structure: Channel proteins in gram negative cells.
- Function: Facilitate diffusion of small molecules (e.g., sugars).
LPS (Lipopolysaccharide) and Lipid A:
- Structure: Found in the outer membrane of gram negative bacteria; Lipid A is the toxic component (endotoxin).
- Function: Structural integrity, protection from host defenses, triggers strong immune responses (endotoxin activity).

Plasmids:
- Structure: Small, circular DNA molecules not part of the chromosome.
- Function: May carry genes for antibiotic resistance or other survival advantages.
Periplasmic Space:
- Structure: Space between the inner and outer membranes in gram negative bacteria.
- Function: Contains enzymes and proteins important for nutrient processing and transport.
Cell Membrane:
- Structure: Phospholipid bilayer with embedded proteins.
- Function: Selective barrier for transport, site of metabolic activity.
Ribosomes:
- Structure: Composed of rRNA and proteins (70S in prokaryotes).
- Function: Protein synthesis.
Inclusions:
- Structure: Storage granules or vesicles.
- Function: Store nutrients, wastes, or gases.

Structure: Found in the outer membrane of gram negative bacteria; consists of Lipid A, core polysaccharide, and O antigen.
Function: Lipid A acts as an endotoxin, triggering strong immune responses such as fever and inflammation.

Function: Endospores allow bacteria to survive extreme heat, toxic chemicals, desiccation, and nutrient depletion.
Characteristics: Highly resistant, metabolically dormant, can survive for long periods, and germinate when conditions improve.

Genera capable of producing endospores: Bacillus and Clostridium.

Passive Transport: Movement of substances down their concentration gradient (high to low) without energy input. Example: osmosis (water movement).
Active Transport: Movement of substances against their concentration gradient (low to high), requiring ATP. Example: phagocytosis.

Hypotonic Solution: Lower solute concentration outside; water enters cell, cell swells, and membrane is pushed against the wall. Cell wall prevents bursting.
Hypertonic Solution: Higher solute concentration outside; water leaves cell, membrane pulls away from wall (plasmolysis), cytoplasm and vacuole shrink.
Isotonic Solution: No net water movement; cell is neither swollen nor shrunken.

Hypotonic Solution: Water enters cell, causing swelling and possible lysis (bursting).
Hypertonic Solution: Water leaves cell, causing shrinkage and membrane distortion.