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Prokaryotic and Eukaryotic Prokaryotic and Eukaryotic CellsCells
Two Main Classes of Cells
• Prokaryotic (Bacteria and Archaea)– Pro = “Before”; Karyon = “Kernel”– No nucleus, DNA coiled up inside cell
• Eukaryotic (Everything else)– Eu = “True”– DNA inside membrane bound organelle inside
cell, the nucleus
3 Domains of LifeEukaryotic Cell (non bacterial)
Prokaryotic Cell (bacteria)
Size DifferencesCell Size: Prokaryotes and eukaryotic cell
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Prokaryotic Diversity: K. Monera• 4000 described species
– Estimated range 400,000-4 million sp.
• Minimal structural diversity
• Tremendous metabolic diversity
• Ecological roles and pathogenesis
Prokaryotic Cell
Bacterial Size, Shape and ArrangementCoccus Bacillus Spiral
Prokaryotic Cell
The Capsule: Frederick Griffith, 1928
• Enhances virulence: attachment and resistance• Forms the foundation of “biofilms”
Gram staining: A clinical tool for distinguishing cell wall composition (Gram-positive and gram-negative bacteria)
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Common bacterial CELL WALL structures as revealed by Gram staining:
Gram positive: thick peptidoglycancell wall
Gram negative: thin peptido. wall + outer memb.
Bacterial Motility: Flagella
Bacterial Growth: Binary fission a simple division process
Movie 1
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Ecological Importance Bacteria and Cyanobacteria
• Nutrient Cycling:– Decomposers– Carbon fixation– Nitrogen fixation– Others
• Symbioses:– Mutualistic: +/+– Commensalistic: +/o– Parasitic: +/-
• Foreign pathogens• Opportunistic pathogens
Prokaryotes• Low morphological diversity (how they looks)• HUGE metabolic diversity!
All organisms can be divided into either of two major groups based upon their pattern of cell structure:
Characteristic Prokaryotic Cell Eukaryotic Cellsize ave. size 1-10 µm ave. size 10-100 µm
nucleus nucleoid(no membrane)
membrane bound
chromosomes single circ. loop ofnaked DNA
linear, arranged withhistones in pairs
organelles absent present, vary withcell function
ribosomes present as smaller 70Sform
present as larger 80Sform
flagella Solid core made offlagellin
9+2 arrangement ofmicrotubules
cell wall present in most sp. aspeptidoglycan
absent or different incomposition
cell reproduction binary fission mitosis and sexualreproduction
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Animal Cell Plant Cell
Evolution of Eukaryotic Cells
• Limits of the P.M.– Surface area revisited
• Differentiation of P.M.• Formation of Organelles
– Compartmentalized Reaction centers– Increase Membrane Surface area– More efficient Metabolism– Increase DNA…which means?
• Leads to Eukaryotic cells…
Eukaryotic Cell Structure: The Factory• Plant and Animal Cell Structure
– Nucleus: the control center– Cytoplasm and Ribosomes: site of protein synthesis– Endoplasmic Reticulum: plumbing, lipid and protein
synthesis– Golgi Apparatus and the secretory pathway– Lysosomes: digestive activity– Chloroplasts and Mitochondria: food and ATP energy– Vacuoles: storage/digestion– Cytoskeleton: structure and movement– Plant Cell Wall: structure, osmosis and turgor pressure
• Family Photos-- structural and functional specializations
Animal Cell The Nucleus•Chromatin= DNA + proteins
•Nucleolus= site of ribosome production
•Endomembrane system
•Interrelated membrane “network” inside of cell
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The Nucleus and Protein Synthesis
Ribosomes
• Protein Synthesis• Free- endogenous proteins• Bound- secretory and membrane bound proteins
The “real” Ribosomes
The Endoplasmic Reticulum• Huge Surface Area• General functions• Rough endoplasmic
reticulum (RER)– Makes more membranes, – Modifies proteins
• Smooth endoplasmic reticulum (SER)– Makes lipids, steroids,
hormones, etc– Detox in the liver– Storage
How the Rough ER Works
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The Golgi ApparatusStorage, refinement, and shipping of ER products
Works in partnership with ER
ER and Golgi complex
Lysosomes
•Sacks of digestive enzymes which break down molecules and organelles in the cells
•Digest food, fight invaders, clean house
•pH of 5
•Apoptosis
•Disorders
Figure 4.10 Lysosome formation
Vacuoles• Sacks which can store enzymes, proteins,
water, and cellular byproducts, waste.• Plants cells often have large Central
Vacuole which holds water and other stuff• Vacuoles also transport things from one
organelle to another withinthe cell
Plant Cell
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Vacuoles Mitochondria and Chloroplasts
• Role in Energy Transformation– Photosynthesis– Cellular respiration
• Evolution– Endosymbiosis Theory
The Chloroplast•Most of the living world depends on chloroplasts for its energy!
•Two membranes on outside
•Complex membrane structure on inside
The Mighty MitochondriaSites of cellular respiration and ATP synthesis
The CytoskeletonThe “skeleton, muscles and highway” of a cell
Cilia and Flagella
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A comparison of the beating of flagella and cilia Support and Joining of Cells
Support and Joining of Cells