Structure of Prokaryotic

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Structure of Prokaryotic Eukaryotic Cells
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Review of Prokaryotic Eukaryotic Cells

• Nucleus vs nucleoid
• DNA circular vs linear, presence of histones
• Membranous organelles
• Cell wall-peptidoglycan
• Cell division binary vs mitosis
• Ribosomes 70S vs 80S
• Cytoskeleton

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Shape

• Cocci
• Diplococci
• Streptococci
• Tetrads
• Sarcinae
• Staphylococci

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Bacillus

• Coccobacilli
• Diplobacilli
• Streptobacilli

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Spiral

• Vibrio-curved rods
• Spirilla-helical rigid
• Spirochetes-helical flexible
• Other shapes
• Pleomorphic

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Glycocalyx

• Glycolipids or glycoproteins
• Surrounds cell
• Capsule or slime layer
• Capsule more organized attached to wall
• Advantages of capsule

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Slime Layer(Biofilm)

• Surrounds cell
• Loosely organized not attached
• Tangled mass of fibers-dextran
• Attachment to surfaces -S. mutans
• Shields bacteria from immune defense
  antibiotics

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Glycocalyx -Eukaryotes

• Animal cells have one
• Made of carbohydrates
• No do not have a cell wall
• Surround plasma membrane
• Stabilizes PM

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Flagella

• Movement
• Spins like propeller
• Clockwise or counter clockwise
• Chemotaxis- movement toward or away

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Arrangements

• Monotrichous one at end
• Amphitrichous both ends
• Lophotrichous tuft at end or ends
• Peritrichous around the cell

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Structure

• Composition-protein subunits flagellin (H
  protein) E. coli H7
• Chains twisted together with hollow core
• Helical shaped
• Filament, hook, basal body
• Hook
• Basal body

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Flagella

• Basal body
• Classified by flagella protein

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Axial Filament

• Spirochetes
• Treponema pallidum-syphilis
• Borrelia burgdorferi-Lyme disease
• Bundle of fibrials within a sheath
• Corkscrew motion

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Movement Eukaryotes

• Flagella cilia
• 92 arrangement of microtubules
• Cilia in Paramecium respiratory cells

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Prokaryote Fimbriae Pili

• Made of pilin string of subunits
• Function attachment
• Few to hundreds
• Fimbrae
• Pili-longer fewer
• Not in eukaryotes

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Cell Wall

• Function
• Basis of Gram stain

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Composition

• Peptidoglycan
• Repeating subunits of disaccharides
• N-acetyl glucosamine (NAG)
• N-acetyl muramic acid (NAM)
• Linked alternately in rows
• Attached by polypeptides
• Tetrapeptide side chains link NAM subunits
• Cross bridge of amino acids link tetrapeptides
• Forms lattice

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Peptidoglycan

• Confers shape prevents lysis
• Cell growth
• Autolysins break cross linkages in peptidoglycan
• Transpeptidases seal breaks
• Penicillin inactivates these enzymes
• Existing cells
• Treat with lysozyme-tears, saliva etc.
• Destroys linkages between carbohydrates

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Gram Positive Cell Wall

• Thick layers 40-80 of dry wt, up to 30 layers
• Contains teichoic acid
• Alcohol and phosphate
• Negative charge
• Cell growth-prevents lysis
• Antigenic properties

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Gram Negative Cell Wall

• Few layers of peptidoglycan- 10
• Outer membrane bilayer
• Periplasm

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LPS

• Strong negative charge
• Barrier to some antibiotics
• Outer membrane-endotoxin
• O polysaccharides
• Lipid-lipid A

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Gram Stain

• Differential stain dev by Hans Gram 1880s
• Classifies bacteria into 2 groups
• Based upon cell wall composition
• Gram variable stain unevenly
• Gram non reactive do not stain or stain poorly

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Comparison

• Gram positives

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Gram Negatives

• ETOH disrupts outer layer
• CV-I complex is washed out of thin peptidoglycan
  layer
• Counterstain

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Atypical Cell Walls

• Streptococci
• Mycobacteria
• Mycoplasma
• PM unique with sterols protect from lysis

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Mycoplasma

• Lack a cell wall so pleomorphic
• Classified with gram positives
• Smallest genome of any bacteria
• Droplet spread-use regular mask
• Why cant you use penicillin?
•      

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Cell wall of Eukaryotes

• Simpler than prokaryotes
• Algae plants
• Fungi
• Yeasts
• Protozoa
• Animals

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Plasma Membrane

• Thin, fluid structure inside cell wall-viscous
• Proteins
• Phospholipids-2 layers

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Functions of Membrane

• Selective permeability
• Passive transport
• Active transport
• Enzymes break down nutrients
• Infoldings

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Plasma Membrane of Eukaryotes

• Phospholipids and proteins
• Carbohydrates and sterols-cholesterol
• More rigid than prokaryotic PM
• Endocytosis
• Exocytosis

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Cytoplasm of Prokaryotes

• 80 water, thick, solutes
• Increase in osmotic pressure on membrane
• Rigid cell wall prevents lysis
• Contains DNA
• Ribosomes
• Inclusion bodies

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Cytoplasm of Eukaryotes

• Cytosol-fluid portion
• Cytoskelton
• Microfilaments
• Microtubules
• Intermediate filaments
• Cytoplasmic streaming

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Ribosomes

• 2 subunits of protein and rRNA
• 70s ribosomes
• Polyribosomes-chains
• Protein synthesis
• Eukayotes-80s

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Inclusions

• Polysaccharide granules
• Sulfur granules
• Reserve deposits-volutin (phosphates)

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Endospores

• Unique to bacteria Clostridium Bacillus
• Sporulation-formation of spores

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Germination

• Triggered by damage to coat
• Enzymes break down endospore
• Water enters metabolism begins
• Not a reproductive structure

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Nuclear Area of Bacteria

• Single, ds DNA chromosome
• Attached to PM at some point
• Nucleoid area, not a nucleus
• Plasmids

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Nucleus

• Largest structure in cell
• Nucleoli
• DNA associated with proteins -histones

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Organelles in Eukaryotes

• Unique to eukaryotes
• Membranous structures
• Endoplasmic reticulum
• Smooth rough
• Golgi complex
• Lysosomes
• Mitochondria
• Cloroplasts

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ER

• Flattened membranous sacs
• Rough ER-ribosomes attached
• Smooth ER- no ribosomes
• Free ribosomes- proteins dont need processing

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Golgi Complex

• Stacks of membranous sacs
• Receive transport vesicles from ER
• Modify molecules to form glycoproteins,
  glycolipids lipoproteins
• Transported in secretory vesicles to PM or to
  outside cell

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Lysosomes

• Formed from Golgi
• Contain digestive enzymes proteases nucleases
• Break down old parts of cell
• Breaks down pathogens

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Mitochondria

• Double membrane
• Generation of ATP

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Chloroplasts

• Thylakoids-flattened membranous sacs
• Contain DNA 70s ribosomes
• Stroma thick fluid in center- Calvin cycle
• Generation of ATP sugars