Chapter 3 Functional Anatomy of Prokaryotic and Eukaryotic Cells

Prokaryotes can be grouped based on morphology Genetically determined Monomorphic vs pleomorphic Size Range 0.2 to 80 um in diameter 2 to 600 um in length Average size: µm × µm

Morphology of Prokaryotic Cells Prokaryotes exhibit a variety of shapes Prokaryotes exhibit a variety of shapes Most common Most common

Spiral

Uncommon Shapes Uncommon Shapes Stella Haloarcula

Cells may form groupings Cells may form groupings Cells adhere together after division Cells adhere together after division Form characteristic arrangements Form characteristic arrangements Depends on plan of division Depends on plan of division

Neisseria Neisseria Enterococcus Enterococcus Micrococcus Micrococcus Sarcina Staphylococcus aureus Staphylococcus aureus

Bacillus anthracis Bacillus megaterium Bordetella pertussis

Layers External to Cell Wall Glycocalyx Glycocalyx Made inside the cell; excreted to surface Made inside the cell; excreted to surface General functions General functions Protection Protection Attachment Attachment Motility Motility

Capsule or Slime Layer Capsule or Slime Layer Chemical composition varies depending on species Chemical composition varies depending on species

Flagella Naked filaments composed of flagellin Naked filaments composed of flagellin Rotate clockwise/counterclockwise Rotate clockwise/counterclockwise Runs and tumbles Runs and tumbles Taxis Taxis

Flagella structure has three basic parts Flagella structure has three basic parts Filament Hook Basal body

Polar - Monotrichous Polar - Monotrichous Peritrichous Polar -Lophotrichous Polar -amphitrichous

Axial filaments Bundles of endoflagella that spiral around cell Bundles of endoflagella that spiral around cell Spirochete bacteria only Spirochete bacteria only Corkscrew motion Corkscrew motion

Attachment Proteins Fimbriae - bacteria Fimbriae - bacteria Filaments of pilin protein Filaments of pilin protein Attachment Attachment Hami – archaea Hami – archaea Hooked protein filament Hooked protein filament Attachment Attachment Sex Pili Sex Pili Pilin tubules Pilin tubules Exchange of DNA Exchange of DNA

Cannulae – thermophilic archaea Cannulae – thermophilic archaea Spinae - marine bacteria Spinae - marine bacteria Connect cells over distances Connect cells over distances Creates mesh-like network Creates mesh-like network

Prokaryotic Cell Wall Determines shape of cell Determines shape of cell Protects from osmotic pressure Protects from osmotic pressure Anchor point for flagella Anchor point for flagella Contributes to virulence Contributes to virulence

Unique chemical structure Unique chemical structure Bacteria vs. Archaea Bacteria vs. Archaea Gram positive vs. Gram-negative Gram positive vs. Gram-negative Peptidoglycan (PTG) (murein) Peptidoglycan (PTG) (murein) Sugar found only in bacteria Sugar found only in bacteria Archaea may have proteins or alternate sugars Archaea may have proteins or alternate sugars

Basic structure of PTG Basic structure of PTG Disaccharide polymer Disaccharide polymer N-acetylglucosamin (NAG) N-acetylglucosamin (NAG) N-acetylmuramic acid (NAM) N-acetylmuramic acid (NAM) Glycan chain held together by amino acids Glycan chain held together by amino acids Tetrapeptide chain Tetrapeptide chain Protein crossbridges may or may not be present Protein crossbridges may or may not be present Mostly G+ Mostly G+

Gram positive cell wall Gram positive cell wall Thick layer of PTG Teichoic acids Lipoteichoic or Wall teichoic acids Polyalcohols that provide antigenic specificity May have external protein or sugar layer

Gram-negative cell wall Gram-negative cell wall Little or no PTG Little or no PTG Outer lipopolysaccharide membrane (LPS) Outer lipopolysaccharide membrane (LPS) O-specific polysaccharide side chain O-specific polysaccharide side chain Lipid A endotoxin Lipid A endotoxin Significant periplasmic space Significant periplasmic space

GRAM STAINING Gram-positive and gram-negative bacteria can be identified using a “gram stain” Gram-positive and gram-negative bacteria can be identified using a “gram stain”

Summary of Gram + vs. Gram – G+ cell G+ cell many rigid layers of peptidoglycan many rigid layers of peptidoglycan teichoic acids teichoic acids No outer LPS membrane No outer LPS membrane 2 ring basal body anchoring flagella 2 ring basal body anchoring flagella G- cell G- cell Little or no peptidoglycan Little or no peptidoglycan no teichoic acids no teichoic acids LPS outer membrane LPS outer membrane 4 ring basal body anchoring flagella 4 ring basal body anchoring flagella

Atypical cell wall Acid-fast cell walls Acid-fast cell walls Classified as gram-positive Classified as gram-positive mycolic acid bound to PTG mycolic acid bound to PTG Mycobacterium Mycobacterium Nocardia Nocardia

Chlamydia Chlamydia Classified as Gram – with no PTG Classified as Gram – with no PTG cysteine-rich proteins cysteine-rich proteins

No cell wall No cell wall Mycoplasmas Mycoplasmas Sterols in plasma membrane Sterols in plasma membrane

Structures Internal to Cell Wall Cytoplasmic membrane Cytoplasmic membrane Delicate thin fluid structure Delicate thin fluid structure Defines boundary Defines boundary Serves as a semi permeable barrier Serves as a semi permeable barrier

Fluid mosaic model Fluid mosaic model Phospholipid Bilayer Amphipathic

Embedded with numerous proteins Embedded with numerous proteins receptors, transport, enzymes receptors, transport, enzymes Prokaryotes typicallydon’t have membrane sterols Prokaryotes typicallydon’t have membrane sterols Bacteria may have hopanoids Bacteria may have hopanoids

Photosynthetic pigments on in-foldings Photosynthetic pigments on in-foldings chromatophores or thylakoids chromatophores or thylakoids

Archaea have distinct membrane lipids Archaea have distinct membrane lipids Ether linkage Ether linkage Diether or tetraether Diether or tetraether Glycerol group enantiomer Glycerol group enantiomer Branched isoprenoid sidechain Branched isoprenoid sidechain May form mono-layer with greater rigidity May form mono-layer with greater rigidity

Top: archaeal phospholipid, 1 isoprene sidechain, 2 ether linkage, 3 L-glycerol, 4 phosphate group Middle:bacterial and eukaryotic phospholipid: 5 fatty acid, 6 ester linkage, 7 D-glycerol, 8 phosphate group Bottom: 9 lipid bilayer of bacteria and eukaryotes, 10 lipid monolayer of some archaea.

Membrane is selectively permeable Membrane is selectively permeable Few molecules pass through freely Few molecules pass through freely Movement involves both active and passive processes Movement involves both active and passive processes

passive processes passive processes no energy (ATP) required no energy (ATP) required Along gradient Along gradient simple diffusion, facilitated diffusion, osmosis simple diffusion, facilitated diffusion, osmosis

Simple diffusion Simple diffusion Facilitated diffusion Facilitated diffusion

Osmosis Osmosis Osmotic pressure Osmotic pressure

active processes active processes energy (ATP) required energy (ATP) required Active transport Active transport

Group translocation Group translocation Phosphotransferase system Phosphotransferase system PEP group translocation PEP group translocation PEP transferase animation

Internal Structures Structures essential for life Structures essential for life Chromosome Chromosome Ribosome Ribosome Optional but may provide selective advantage Optional but may provide selective advantage Cytoskeleton Cytoskeleton Plasmid Plasmid Storage granules Storage granules Endospores Endospores

Internal Structures Primary Chromosome Primary Chromosome Resides in nucleoid Resides in nucleoid Typically single circular chromosome Typically single circular chromosome Archaea - histone proteins Archaea - histone proteins Bacteria - condensin protiens Bacteria - condensin protiens Asexual reproduction Asexual reproduction Binary fission, budding, fragmenting, spores Binary fission, budding, fragmenting, spores

Plasmids Plasmids Small DNA molecules Small DNA molecules replicated independently replicated independently nonessential information nonessential information used in genetic engineering biotechnology used in genetic engineering biotechnology

Ribosomes (70S) Ribosomes (70S) Composed of large and small subunits Composed of large and small subunits made of riboprotein and ribosomal RNA made of riboprotein and ribosomal RNA differ in density from eukaryotic ribosomes differ in density from eukaryotic ribosomes

InclusionsInclusions Metachromatic granules Metachromatic granules Polysaccharide granules Polysaccharide granules lipid inclusions lipid inclusions sulfur granules sulfur granules carboxyzomes carboxyzomes magnetosomes magnetosomes Gas vesicles Gas vesicles

Endospores Endospores “Resting cells” “Resting cells” Highly resistant Highly resistant Heat, desiccation, chemicals and UV light Heat, desiccation, chemicals and UV light Not reproduction! Not reproduction! Endospore producers include Clostridium and Bacillus