Structure of Prokaryotes
Hugh B. Fackrell
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Prokaryotes
Computer Filename: Struct1.ppt
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Presentation Outline
Cell shapes
 Eubacteria vs Archeobacteria
 Cell Envelope
 Spores
 Flagella
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Background Terms & Concepts
Proteins
 Membranes (membr.ppt)
 Formation of lipid bilayers (membr.ppt)
 Prokaryotes
 Prokaryotes vs eukaryotes
 Evolution of eukaryotes
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Major Groups of Organisms
Plants
 Animals
 Fungi
 Protista
 Prokaryotes
 Viruses
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Prokaryotes
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Characteristics
– No nucleus or nuclear membrane
– Microscopic
– Food organic or inorganic
– Some photosynthetic
Bacteria
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Cyanobacteria
Eubacteria
Archaea (archaebacteria)
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Prokaryotes vs Eukaryotes
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Prokaryotes
No nuclear
membrane
DNA in ONE
molecule free in
cytoplasm
No membrane
bound organelles
No cytoskeleton
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Eukaryotes
Nuclear membrane
DNA organized in
several molecules
(chromosomes)
Many different
membrane bound
organelles
Cytoskeleton
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Circular Bacterial DNA
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Prokaryotes (details)
Size:1-10 m
 Flagella: simple, 2 proteins
 Capsule: extracellular polymer
 Cell wall: usual, complex
 Plasma membrane: no carbohydrates or sterols
 Ribosomes: small(70S)
 Cell division: binary fission
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Eukaryotes (details)
Size:10-100 m
 Flagella: Complex, many microtublules
 Capsule: none
 Cell wall: if present chemically simple
 Plasma membrane:Sterols & carbohydrates
 Ribosomes: large (80S) in cytoplasm
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– small(70S) in organelles
 Cell
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division: mitosis
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Cell Sizes
Cell
Smallest Average Largest
 Bacterial 0.1m
1-2 m 0.9 mm
 Animal
1
5- 20
10 m
 Plant
1
50
?
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Microbial Colossus
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0.5 mm
visibile to naked eye
Symbiant in gut of
surgeonfish
Epulopiscium fishelsoni
How does solve
diffusion problems?
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Bacterial Shapes
Coccus “Berry”
 Rod: (bacillus) “Rod or staff”
 Vibrio: comma one turn of a helix
 Spiral: rigid, open coil
 Spirochete: flexible tight coil
 Square:
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Coccus
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Division in Single Plane
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Bacterial Fossils 3.7 BY
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Rod
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Gold deposited by Bacteria
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Vibrio
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Magnetic Bacterium
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Spiral
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Spirochete
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Diagram of Prokaryote
Bacterial flagellum
Mesosome
Ribosomes
DNA
of nucleoid
Plasma membrane
Cell wall
Capsule
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(a)
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Bacterial chains
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Filamentous bacteria
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Gram Positive Cells
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Gram Negative Cells
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Bacterial Cell Walls
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Bacterial Wall [detail]
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Gm Negative Cell Wall
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Isolated Murein Layer
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After Peptidase hydrolysis
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Cleavage Site of Lysozyme
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Archaea: Cell Membranes
lack fatty acids
 contain ethers
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– gylcerol diethers , bilayers
– Tetraethers form monolayers
– Fixed number of carbons in hydrocarbons
– flexibility via pentacylic rings
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Large amounts of nonpolar lipids
– isoprenoids eg squalene
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Archaea: Cell Walls
NO muramic acid
 NO D amino acids
 pseudopeptidoglycan
(Methanobacterium)
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– N acetyltalosaminuronic acid
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glycoprotein (Halobacterium)
– highly negative charge balances positive
charges of sodium
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Protein
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Archaea: Genetics
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Half size of bacterial genomes
– 1900 KB vs 4700 KB (E coli)
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Bacterial Similarities
– Polygenic mRNA
– Shine-Dalgarno sequences for ribosome
binding
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Eucarya Similarities
– RNA polymerase II
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Bacterial Endopsore
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Questions
Diagram the structure of murein
 Construct a table comparing Eubacteria
and the Archeo
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Bacterial Flagellum
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Summary
Simple cells
 Single circular chromosome
 1-2 microns in size
 few internal compartments or
organelles
 Complex Cell Wall common
 Cell wall unique
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