Transcript The Biotechnology Century and Its Workforce

Functional Anatomy of
Prokaryotic and Eukaryotic Cells
Chapter 4
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QUESTION OF THE DAY….
 Penicillin was called
a “miracle drug”
because it doesn’t
harm human cells.
Why doesn’t it?
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Prokaryotic and Eukaryotic Cells
 Prokaryote comes from the Greek words for
prenucleus.
 Eukaryote comes from the Greek words for
true nucleus.
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Prokaryote
Eukaryote
 One circular
chromosome, not in a
membrane
 No histones
 No organelles
 Peptidoglycan cell walls
if Bacteria
 Pseudomurein cell walls
if Archaea
 Binary fission
 Paired chromosomes,
in nuclear membrane
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 Histones
 Organelles
 Polysaccharide cell
walls
 Mitotic spindle
Prokaryotic Cells: Shapes
 Average size: 0.2 –1.0 µm  2 – 8 µm
 Most bacteria are monomorphic
 A few are pleomorphic
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Figure 4.7a
Basic Shapes
 Bacillus (rod-shaped)*
 Coccus (spherical)
 Spiral
 Spirillum
 Vibrio
 Spirochete
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Figures 4.1a, 4.2a, 4.2d, 4.4a, 4.4b, 4.4c
Arrangements
 Pairs: Diplococci,
diplobacilli
 Clusters:
Staphylococci
 Chains:
Streptococci,
streptobacilli
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Figures 4.1a, 4.1d, 4.2b, 4.2c
The Structure of a Prokaryotic Cell
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Figure 4.6
Glycocalyx
 Outside cell wall
 Usually sticky
 Capsule: neatly
organized
 Slime layer: unorganized
and loose
 Extracellular
polysaccharide allows
cell to attach
 Capsules prevent
phagocytosis
QUESTION: Why are bacterial capsules medically important?
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Figure 24.12
Flagella
 Outside cell wall
 Made of chains of
flagellin
 Attached to a protein
hook
 Anchored to the wall
and membrane by the
basal body

Note the basal body attachment in a
Gram + verses – cell
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Figure 4.8b
Arrangements of Bacterial Flagella
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Figure 4.7
Motile Cells
 Rotate flagella to
run or tumble
 Move toward or
away from stimuli
(taxis)
 Flagella proteins
are H antigens
(e.g., E. coli
O157:H7)
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Axial Filaments
 Also called endoflagella
 In spirochetes
 Anchored at one end
of a cell
 Rotation causes cell
to move
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Figure 4.10a
Fimbriae and Pili
 Fimbriae allow
attachment
 Pili
 Facilitate transfer
of DNA from one
cell to another
 Gliding motility
 Twitching
motility
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Figure 4.11
The Cell Wall
 Prevents osmotic
lysis
 Made of
peptidoglycan (in
bacteria)
 Polymer of
disaccharide:
 Nacetylglucosamin
e (NAG)
 N-acetylmuramic
acid (NAM)
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Figure 4.6
Gram-Positive Bacterial Cell Wall
Note: Peptidoglycan is linked by polypeptides and there are multiple layers of
peptidoglycan.
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Figure 4.13b
Gram-Negative Bacterial Cell Wall
Note: Thin layer of peptidoglycan and it is covered by the LPS layer
which contains O polysaccharide, core polysaccharide and lipid A.
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Figure 4.13c
Gram-Positive Cell Walls
 Teichoic acids
 Lipoteichoic acid links to plasma membrane
 Wall teichoic acid links to peptidoglycan
 May regulate movement of cations
 Polysaccharides provide antigenic variation
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Figure 4.13b
Gram-Negative Cell Wall
Note: Lipopolysaccharides, lipoproteins, phospholipids
form the periplasm between the outer membrane and the plasma membrane
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Figure 4.13c
Gram-Negative Outer Membrane
 Protection from phagocytes, complement, and
antibiotics
 O polysaccharide antigen, e.g., E. coli O157:H7
 Lipid A is an endotoxin
 Porins (proteins) form channels through membrane
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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-Positive
Cell Wall
Gram-Negative
Cell Wall
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Thick peptidoglycan
Teichoic acids
2-ring basal body
Disrupted by lysozyme
Penicillin sensitive
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Thin peptidoglycan
Outer membrane
Periplasmic space
4-ring basal body
Endotoxin
Tetracycline sensitive
Figure 4.13b–c
Atypical Cell Walls
 Acid-fast cell walls
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Like gram-positive
Waxy lipid (mycolic acid) bound to peptidoglycan
Mycobacterium
Nocardia
QUESTION: Why are drugs that target cell wall synthesis useful?
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Figure 24.8
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
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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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The Plasma Membrane
 Phospholipid
bilayer
 Peripheral
proteins
 Integral proteins
 Transmembrane
 Proteins
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Figure 4.14b
Fluid Mosaic Model
 Membrane is as viscous as olive oil
 Proteins move to function
 Phospholipids rotate
and move laterally
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Figure 4.14b
The Plasma Membrane
 Selective permeability allows passage of some
molecules
 Enzymes for ATP production
 Photosynthetic pigments on foldings called
chromatophores or thylakoids
 Damage to the membrane by alcohols, quaternary
ammonium (detergents), and polymyxin antibiotics
causes leakage of cell contents
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Chromatophores
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Figure 4.15
Movement of Materials across
Membranes
 Simple diffusion:
Movement of a solute
from an area of high
concentration to an
area of low
concentration
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Figure 4.17a
Movement of Materials across
Membranes
 Facilitated diffusion: Solute combines with a
transporter protein in the membrane
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Figure 4.17b-c
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
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Figure 4.18a
Movement of Materials across
Membranes
 Through lipid layer
 Aquaporins (water
channels)
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Figure 4.17d
The Principle of Osmosis
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Figure 4.18c–e
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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Bacterial Cell Components
 Cytoplasm: The substance inside the plasma
membrane
 Nucleoid: Bacterial chromosome
 Ribosome: Protein factory
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Figure 4.6
The Prokaryotic Ribosome
 Protein synthesis
 70S
 50S + 30S subunits
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Figure 4.19
Magnetosomes
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Figure 4.20
Inclusions
 Metachromatic granules
(volutin)
 Polysaccharide granules
 Lipid inclusions
 Sulfur granules
 Carboxysomes
 Gas vacuoles
 Magnetosomes
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 Phosphate reserves
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Energy reserves
Energy reserves
Energy reserves
Ribulose 1,5-diphosphate
carboxylase for CO2 fixation
 Protein-covered cylinders
 Iron oxide
(destroys H2O2)
Endospores
 Resting cells
 Resistant to
desiccation, heat,
chemicals
 Bacillus, Clostridium
 Sporulation:
Endospore formation
 Germination: Return
to vegetative state
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Formation of Endospores by
Sporulation
Figure 4.21a
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The Eukaryotic Cell
Figure 4.22a
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Flagella and Cilia
Figure 4.23a-b
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Flagella and Cilia
 Microtubules
 Tubulin
 9 pairs + 2 array
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Figure 4.23c
The Cell Wall and Glycocalyx
 Cell wall
 Plants, algae, fungi
 Carbohydrates
 Cellulose, chitin, glucan, mannan
 Glycocalyx
 Carbohydrates extending from animal plasma membrane
 Bonded to proteins and lipids in membrane
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QUESTION OF THE DAY….
 Penicillin was called a
“miracle drug” because
it doesn’t harm human
cells. Why doesn’t it?
Copyright © 2010 Pearson Education, Inc.
The Plasma Membrane
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Phospholipid bilayer
Peripheral proteins
Integral proteins
Transmembrane proteins
Sterols
Glycocalyx carbohydrates
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The Plasma Membrane
 Selective permeability allows passage of some
molecules
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Simple diffusion
Facilitative diffusion
Osmosis
Active transport
Endocytosis
 Phagocytosis: Pseudopods extend and engulf particles
 Pinocytosis: Membrane folds inward, bringing in fluid
and dissolved substances
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Cytoplasm
 Cytoplasm : Substance inside plasma membrane
and outside nucleus
 Cytosol: Fluid portion of cytoplasm
 Cytoskeleton: Microfilaments, intermediate
filaments, microtubules
 Cytoplasmic streaming: Movement of cytoplasm
throughout cells
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Ribosomes
 Protein synthesis
 80S
 Membrane-bound: Attached to ER
 Free: In cytoplasm
 70S
 In chloroplasts and mitochondria
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Organelles
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Nucleus: Contains chromosomes
ER: Transport network
Golgi complex: Membrane formation and secretion
Lysosome: Digestive enzymes
Vacuole: Brings food into cells and provides support
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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Rough Endoplasmic Reticulum
Figure 4.25
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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 4.28b
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Peroxisome and Centrosome
Figure 4.22b
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Endosymbiotic Theory
Figure 10.2
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Endosymbiotic Theory
QUESTION: Which three organelles are not associated with the Golgi
complex? What does this suggest about their origin?
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