Ch 4

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Ch 4
prokaryotic

• Functional anatomy of Bacteria and other Microbes

Eukaryotic
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OrThe differences between Eukaryotic and
Prokaryotic cells
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QA

• Penicillin was called a miracle drug because it
  doesnt harm human cells. Why doesnt it?

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• Proks and euks are similar in chemical
  composition and reaction

• Proks lack membrane bound organelles
• Only Proks have peptidoglycan
• Euks have membrane bound organelles
• Euks have paired chromosomes
• Euks have histones

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Nick sees the difference mainly in information
and structural capacity

• Proks lack membrane-enclosed organelles
• Euks are like a 2mhz 100gb home computer
• Proks are like a calculator
• Human genome 4x109
• E. coli 4x106

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The prokaryote

• Unicellular
• Multiply by binary fission
• Differentiated by
• Morphology
• Chemical composition
• Nutritional requirements
• Biochemical activates
• Sources of energy
• Other tests

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Size

• 0.2 to 2um in diameter
• 2-8um in length
• In biological systems there are always exceptions
  these are general sizes.

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Shape
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Shape

• Coccus
• Diplococci
• Streptococci
• Staphylococci
• Bacillus
• Spiral
• Other pleomorphic shapes

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Basic components of a bacterial cell fig 4.6
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Parts not seen

• Glycocalyx
• Capsule
• Slime layer
• Extracellular polysaccharide
• Function
• Toxicity

• Protect from phagocytosis
• Allow adherence
• Reduce water loss
• Collect nutrients

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Flagella long filamentous appendages with
filament, hook and basal body

• Used in movement
• Can present taxis
• Negative
• Positive
• Monotrichous
• Peritrichous
• Flagellar H protein acts as an antigen E.c
  O157H7
• Flagellin

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Flagella Arrangement
Figure 4.7
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Fimbriae/pili

• Shorter and less complex than flagella
• Helps adhere to surfaces
• Used for sex and communication

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Cell wall

• Major difference between eukaryotic and prok
  orgs.
• Surrounds plasma membrane provides protection
• Peptidoglycan
• Polymer of
• NAG
• NAM
• Short amino acid chain
• Production inhibited by antibiotics
• Prevents osmotic damage
• Damage to cw is almost always lethal except

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Gram Positives have large cell wall and Teichoic
acids
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Gram neg have lipopolysaccharide
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Peptidoglycan

• Polymer of disaccharide
• N-acetylglucosamine (NAG)
• N-acetylmuramic acid (NAM)

Figure 4.12
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Peptidoglycan in Gram-Positive Bacteria
Figure 4.13a
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The Cell Wall

• Prevents osmotic lysis
• 4-7 Differentiate protoplast, spheroplast, and L
  form.
• Made of peptidoglycan (in bacteria)
• Linked by polypeptides

Figure 4.6
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Gram-Positive Bacterial Cell Wall
Figure 4.13b
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Gram-Negative Bacterial Cell Wall
Figure 4.13c
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Gram-positiveCell Wall
Gram-positiveCell Wall

• Thin peptidoglycan
• Outer membrane
• Periplasmic space

• Thick peptidoglycan
• Teichoic acids

Figure 4.13bc
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Gram neg

• Lipoprotein phospholipid outer membrane
  surrounding a thin peptidoglycan
• Makes gram neg resistant to
• Phagocytosis
• Antibiotics
• Chemical reactions
• Enzymes (lysozyme)
• Has lipid A endotoxin
• O polysaccaride antigen O157H7 E.c.

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Gram-Negative Outer Membrane
Figure 4.13c
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How the gram stain works to differentiate between
G and G-
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The Gram Stain

1. Gram-Positive

(b) Gram-Negative
Table 4.1
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The Gram Stain Mechanism

• Crystal violet-iodine crystals form in cell
• Gram-positive
• Alcohol dehydrates peptidoglycan
• CV-I crystals do not leave
• Gram-negative
• Alcohol dissolves outer membrane and leaves holes
  in peptidoglycan
• CV-I washes out

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Gram-PositiveCell Wall
Gram-NegativeCell Wall

• 4-ring basal body
• Endotoxin
• Tetracycline sensitive

• 2-ring basal body
• Disrupted by lysozyme
• Penicillin sensitive

Figure 4.13bc
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Nontypical cell walls

• Mycoplasma (acid fast) do not have ppt containing
  cell wall.
• Archaea contain another chemical called
  pseudomurein

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Atypical Cell Walls

• Acid-fast cell walls
• Like gram-positive
• Waxy lipid (mycolic acid) bound to peptidoglycan
• Mycobacterium
• Nocardia

Figure 24.8
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Atypical Cell Walls

• Mycoplasmas
• Lack cell walls
• Sterols in plasma membrane
• Archaea
• Wall-less or
• Walls of pseudomurein (lack NAM and D-amino acids)

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Damage to the Cell Wall

• Lysozyme digests disaccharide in peptidoglycan
• Penicillin inhibits peptide bridges in
  peptidoglycan
• Protoplast is a wall-less cell
• Spheroplast is a wall-less gram-positive cell
• Protoplasts and spheroplasts are susceptible to
  osmotic lysis
• L forms are wall-less cells that swell into
  irregular shapes

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Plasma membrane

• Defines the living and nonliving parts of the
  cell
• Everything on the inside is living
• Everything on the outside is not living
• Is selectively permeable
• Workspace for enzymes of metabolic reactions

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Plasma Membrane

• Phospholipid bilayer
• Peripheral proteins
• Integral proteins
• Transmembrane proteins

Figure 4.14b
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PM Workspace

• Nutrient breakdown
• Energy production
• Photosynthesis
• Afforded by mesosomes which are regular
  infoldings of the plasma membrane
• Weaknesses destroyed by actions of alcohols,
  detergents and polymyxins

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Fluid Mosaic Model

• Membrane is as viscous as olive oil.
• Proteins move to function
• Phospholipids rotate and move laterally

Figure 4.14b
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Plasma Membrane

• Damage to the membrane by alcohols, quaternary
  ammonium (detergents) and polymyxin antibiotics
  causes leakage of cell contents.

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Movement of Materials across Membranes

• Simple diffusion Movement of a solute from an
  area of high concentration to an area of low
  concentration

Figure 4.17a
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Movement of Materials across Membranes

• Facilitated diffusion Solute combines with a
  transporter protein in the membrane

Figure 4.17b-c
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Movement of Materials across Membranes
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Movement of Materials across Membranes

• Osmosis The movement of water across a
  selectively permeable membrane from an area of
  high water to an area of lower water
  concentration
• Osmotic pressure The pressure needed to stop the
  movement of water across the membrane

Figure 4.18a
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Movement of Materials across Membranes

• Through lipid layer
• Aquaporins (water channels)

Figure 4.17d
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The Principle of Osmosis
Figure 4.18ab
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The Principle of Osmosis
Figure 4.18ce
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Movement of Materials across Membranes

• Active transport Requires a transporter protein
  and ATP
• Group translocation Requires a transporter
  protein and PEP

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Cytoplasm's

• The liquid component of the cell within the PM
• Mostly water, dissolved ions, DNA ribosomes and
  inclusions
• Concept of homeostasis

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Nuclear area

• Contains the bacterial chromosome
• Bacteria may also have plasmids with up to 25 of
  the genetic materials

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Ribosomes
Figure 4.6a
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Ribosomes
Figure 4.19
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Inclusions

• Typically reserve deposits of excess materials
  like inorganic phosphate
• Polysaccharide granules
• Lipids
• Sulfur
• Gas
• iron

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The Prokaryotic Ribosome

• Protein synthesis
• 70S
• 50S 30S subunits

Figure 4.19
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Magnetosomes
Figure 4.20
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Inclusions

• Metachromatic granules (volutin)
• Polysaccharide granules
• Lipid inclusions
• Sulfur granules
• Carboxysomes
• Gas vacuoles
• Magnetosomes

• Phosphate reserves
• Energy reserves
• Energy reserves
• Energy reserves
• Ribulose 1,5-diphosphate carboxylase for CO2
  fixation
• Protein-covered cylinders
• Iron oxide (destroys H2O2)

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Endospores

• Resting and waiting stage
• Resistant to drying and other harsh conditions

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The Eukaryotic cell
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Comparison

• Flagella and cilia tubulin (9/2) arrangement
• Cell wall of different materials
• Glycocalyx
• Plasma membrane

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organelles

• Nucleus
• ER
• 80s ribosomes
• Golgi complex
• Lysozymes
• Vacuoles
• Mitochondria
• Chloroplasts
• Peroxisomes

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Organelles

• 4-18 Define organelle.
• 4-19 Describe the functions of the nucleus,
  endoplasmic reticulum, Golgi complex, lysosomes,
  vacuoles, mitochondria, chloroplasts,
  peroxisomes, and centrosomes.

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Organelles

• Nucleus Contains chromosomes
• ER Transport network
• Golgi complex Membrane formation and secretion
• Lysosome Digestive enzymes
• Vacuole Brings food into cells and provides
  support

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Organelles

• Mitochondrion Cellular respiration
• Chloroplast Photosynthesis
• Peroxisome Oxidation of fatty acids destroys
  H2O2
• Centrosome Consists of protein fibers and
  centrioles

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The Eukaryotic Nucleus
Figure 4.24
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The Eukaryotic Nucleus
Figure 4.24ab
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Rough Endoplasmic Reticulum
Figure 4.25
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Detailed Drawing of Endoplasmic Reticulum
Figure 4.25a
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Micrograph of Endoplasmic Reticulum
Figure 4.25b
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Golgi Complex
Figure 4.26
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Lysosomes and Vacuoles
Figure 4.22b
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Mitochondria
Figure 4.27
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Chloroplasts
Figure 4.28
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Chloroplasts
Figure 4.28a
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Chloroplasts
Figure 4.28b
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Peroxisome and Centrosome
Figure 4.22b
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Eukaryotic Cell

• Not membrane-bound
• Ribosome Protein synthesis
• Centrosome Consists of protein fibers and
  centrioles
• Centriole Mitotic spindle formation

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Evolution of eukaryotes

• Endosymbiotic theory

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Membrane activity

• Diffusion
• Osmosis
• Passive diffusion
• Facilitated diffusion
• Active transport
• Know the relationships

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Movement Across Membranes

• Active transport of substances requires a
  transporter protein and ATP.
• Group translocation of substances requires a
  transporter protein and PEP.

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