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Chapter 4
Functional Anatomy of
Prokaryotic and Eukaryotic
Cells
© 2013 Pearson Education, Inc.
Lectures prepared by Christine L. Case
Prokaryotic and Eukaryotic
Cells
• Prokaryote comes from the Greek words for prenucleus.
• Eukaryote comes from the Greek words for
true nucleus.
Prokaryote
Eukaryote
• One circular
chromosome, not in a
membrane
• No organelles
• Bacteria: peptidoglycan
cell walls
• Archaea: pseudomurein
cell walls
• Binary fission
• Paired chromosomes,
in nuclear membrane
• 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
Figure 4.9b Flagella and bacterial motility.
A Proteus cell in the swarming stage may have
more than 1000 peritrichous flagella.
Basic Shapes
• Bacillus (rod-shaped)
• Coccus (spherical or circular)
• Spiral
• Spirillum
• Vibrio
• Spirochete
Figure 4.1a Arrangements of cocci.
Plane of
division
Diplococci
Streptococci
Figure 4.2ad Bacilli.
Single bacillus
Coccobacillus
Figure 4.4 Spiral bacteria.
Vibrio
Spirillum
Spirochete
Bacillus or Bacillus
• Scientific name: Bacillus
• Shape: bacillus
Figure 4.5a Star-shaped and rectangular prokaryotes.
Star-shaped bacteria
Figure 4.5b Star-shaped and rectangular prokaryotes.
Rectangular bacteria
Arrangements
• Pairs: diplococci, diplobacilli
• Clusters: staphylococci
• Chains: streptococci, streptobacilli
Figure 4.1ad Arrangements of cocci.
Plane of
division
Diplococci
Streptococci
Staphylococci
Figure 4.2b-c Bacilli.
Diplobacilli
Streptobacilli
Figure 4.6 The Structure of a Prokaryotic Cell.
Pilus
Cell wall
The drawing below and the
micrograph at right show a bacterium Capsule
sectioned lengthwise to reveal the
Although the nucleoid appears
internal composition. Not all bacteria
split in the photomicrograph,
have all the structures shown; only
the thinness of the “slice” does
structures labeled in red are found in
not convey theobject’s depth.
all bacteria.
Cytoplasm
70S Ribosomes
Plasma membrane
Nucleoid containing DNA
Inclusions
Plasmid
Fimbriae
Capsule
Cell wall
Plasma
membrane
Flagella
.
© 2013 Pearson Education, Inc.
Glycocalyx
• Outside cell wall
• Usually sticky
• Capsule: neatly organized
• Capsules prevent phagocytosis
• Hard to get rid of
• Slime layer: unorganized and loose
• Can be rinsed off with disinfectants
• Extracellular polysaccharide allows cell to attach
• Important component of biofilms
Figure 24.12 Streptococcus pneumoniae, the cause of pneumococcal pneumonia.
Flagella
•
•
•
•
Outside cell wall
Made of chains of flagellin
Attached to a protein hook
Anchored to the wall and membrane by the
basal body
• Rotate flagella to run or tumble
• Move toward or away from stimuli (taxis)
Figure 4.8b The structure of a prokaryotic flagellum.
Grampositive
Flagellum
Filament
Cell wall
Hook
Basal body
Peptidoglycan
Plasma
membrane
Cytoplasm
Parts and attachment of a flagellum of a
gram-positive bacterium
Figure 4.8a The structure of a prokaryotic flagellum.
Flagellum
Gramnegative
Cell wall
Filament
Hook
Basal body
Peptidoglycan
Outer
membrane
Plasma
Cytoplasm
membrane
Parts and attachment of a flagellum of a
gram-negative bacterium
Figure 4.9a Flagella and bacterial motility.
Run
Tumble
Run
Tumble
Run
Tumble
A bacterium running and tumbling. Notice that the
direction of flagellar rotation (blue arrows) determines
which of these movements occurs. Gray arrows indicate
direction of movement of the microbe.
Figure 4.7 Arrangements of bacterial flagella.
Peritrichous
Lophotrichous and polar
Monotrichous and polar
Amphitrichous and polar
Axial Filaments
• Also called
endoflagella
• In spirochetes
• Anchored at one end
of a cell
• Rotation causes cell
to move
Figure 4.10b Axial filaments.
Outer sheath
Cell wall
Axial filament
A diagram of axial filaments wrapping around
part of a spirochete (see Figure 11.26a for a
cross section of axial filaments)
Fimbriae and Pili
• Found on many gram NEGATIVE bacteria
• Short, thin, hairlike appendages
• 2 Types:
1. Fimbriae
• Allow attachment which usually leads to infection
• Different numbers
2. Pili
• Facilitate transfer of DNA from one cell to another
• Motility
• 1-2 per cell
Figure 4.11 Fimbriae.
Fimbriae
The Cell Wall
• Prevents osmotic
lysis
• Made of
peptidoglycan (in
bacteria)
CELL WALL
Differences in Cell Walls
GRAM POSITIVE
• Thick peptidoglycan
• Teichoic acids
• May regulate movement
of cations
• Penicillin sensitive
GRAM NEGATIVE
 Thin peptidoglycan
 Outer membrane
 Lipopolysaccharides
 Protection from
phagocytes, complement,
and antibiotics
 Tetracycline Sensitive
Figure 4.13b-c Bacterial cell walls.
Peptidoglycan
Wall teichoic acid
Lipoteichoic
acid
Cell wall
Plasma
membrane
Protein
O polysaccharide
Core polysaccharide
Gram-positive cell wall
Core polysaccharide
O polysaccharide
Lipopolysaccharide
Lipid A
Cell wall
Gram-negative cell wall
Lipid A
Parts of the LPS
Porin protein
Lipoprotein
Outer membrane
Phospholipid
Peptidoglycan
Plasma
membrane
Periplasm
Protein
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
Table 4.1 Some Comparative Characteristics of Gram-Positive and Gram-Negative Bacteria
Atypical Cell Walls
• Acid-fast cell walls
• Like gram-positive cell walls
• Waxy lipid (mycolic acid) bound to peptidoglycan
• 2 Genera:
• Mycobacterium
• Nocardia
Figure 24.8 Mycobacterium tuberculosis.
Atypical Cell Walls
• Mycoplasmas
• Lack cell walls
• Sterols in plasma membrane
• Archaea
• Wall-less
• Walls without peptidoglycan
Damage to the Cell Wall
•
•
•
•
Lysozyme- enzyme that digests peptidoglycan
Penicillin- inhibits peptide bridges in peptidoglycan
Protoplast- wall-less cell gram-positive cell
Spheroplast- wall-less gram-negative cell
• Protoplasts and spheroplasts are susceptible to osmotic lysis
• L forms-wall-less cells that swell into irregular shapes
Figure 4.14a Plasma membrane.
Lipid
bilayer of plasma
membrane
Peptidoglycan
Outer membrane
Plasma membrane
of cell
The Plasma Membrane
• Selectively permeable
• Produce ATP
• Damage to the membrane by alcohols, ammonium
(detergents), and polymyxin antibiotics causes leakage of cell
contents
• Phospholipid bilayer
• Proteins:
1.
Peripheral proteins- inner or outer surface
• Act as enzymes
• Support
• Changes in shape during movement
2.
Integral proteins (transmembrane)-penetrate membrane
completely
• Channels or pores through which substance leave and enter the cell
Figure 4.14b Plasma membrane.
Outside
Lipid
bilayer
Pore
Peripheral protein
Inside
Polar head
Nonpolar fatty
acid tails
Polar head
Lipid bilayer of plasma membrane
Integral
proteins
Peripheral protein
Movement of Materials
across Membranes
• Simple diffusion:
movement of a
solute from an area
of high concentration
to an area of low
concentration
Movement of Materials
across Membranes
• Facilitated diffusion:
solute combines with
a transporter protein
in the membrane
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
Movement of Materials
across Membranes
• Through lipid layer
• Aquaporins (water
channels)
Figure 4.18c-e The principle of osmosis.
Cytoplasm Solute
Plasma
membrane
Water
Isotonic solution.
No net movement
of water occurs.
Hypotonic solution. Water moves
into the cell. If the cell wall is
strong, it contains the swelling. If
the cell wall is weak or damaged,
the cell bursts (osmotic lysis).
Hypertonic solution.
Water moves out of the
cell, causing its cytoplasm
to shrink (plasmolysis).
Movement of Materials
across Membranes
• Active transport: requires a transporter protein and ATP
• Group translocation: requires a transporter protein and the substance
going across the protein is CHEMICALLY changed
Cytoplasm
• The substance inside the plasma membrane
• Contains 80% water
• Contains major structures of the cell
Genetic Information
• Bacterial chromosomegenetic information for
the cell’s structure and
function;usually circular
• Plasmidextrachromosomal
genetic information; may
carry genes for antibiotic
resistance, tolerance to
metals, toxin production
The Prokaryotic Ribosome
• Protein synthesis
• 70S
• 50S + 30S subunits
Inclusions
 Reserve deposits
 Store nutrients to have in times of need.
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Endospores
•
•
•
•
•
Resting cells
Resistant to desiccation, heat, chemicals
Bacillus, Clostridium
Sporulation: endospore formation
Germination: return to vegetative state
Figure 4.21b Formation of endospores by sporulation.
Endospore
An endospore of Bacillus subtilis
Figure 4.21a Formation of endospores by sporulation.
Cell wall
Cytoplasm
Spore septum begins to isolate
newly replicated DNA and a
small portion of cytoplasm.
Plasma membrane starts to
surround DNA, cytoplasm, and
membrane isolated in step 1.
Plasma
membrane
Bacterial
chromosome
(DNA)
Sporulation, the process of endospore
formation
Spore septum surrounds isolated portion,
forming forespore.
Two
membranes
Peptidoglycan
layer forms between membranes.
Endospore is freed
from cell.
Spore coat forms.
Figure 4.22a Eukaryotic cells showing typical structures.
PLANT CELL
ANIMAL CELL
Peroxisome
Flagellum
Mitochondrion
Microfilament
Golgi complex
Microtubule
Vacuole
Chloroplast
Ribosome
Cytoplasm
Smooth endoplasmic
reticulum
Cell wall
Nucleus
Nucleolus
Golgi complex
Basal body
Cytoplasm
Microfilament
Lysosome
Centrosome:
Centriole
Pericentriolar material
Ribosome
Microtubule
Nucleus
Nucleolus
Plasma membrane
Highly schematic diagram of a composite eukaryotic cell,
half plant and half animal
Peroxisome
Rough endoplasmic
reticulum
Mitochondrion
Smooth endoplasmic
reticulum
Plasma membrane
Figure 4.23a-b Eukaryotic flagella and cilia.
Flagellum
Cilia
A micrograph of
Euglena, a chlorophyllcontaining alga, with its
flagellum.
A micrograph of
Tetrahymena, a common
freshwater protozoan,
with cilia.
Flagella and Cilia
• Microtubules- long
hollow tubes
• 9 pairs + 2
arrangement
• Flagella- move in a
wavelike manner.
The Cell Wall and Glycocalyx
• Cell wall
• Plants, algae, fungi
• Cellulose (Plants)
• Chitin (Fungi)
• Glucan and Mannan (Yeasts)
• Glycocalyx
• Carbohydrates extending from plasma membrane
• Strengthens cell surface, attachment of cells together, cell-cell
recognition
The Plasma Membrane
•
•
•
•
•
Phospholipid bilayer
Peripheral proteins
Integral proteins
Transmembrane proteins
Sterols- important in cells without cell wall because it offers
stability to the cell
• Glycocalyx carbohydrates
The Plasma Membrane
•
•
•
•
•
•
Selective permeability allows passage of some molecules
Simple diffusion
Facilitative diffusion
Osmosis
Active transport
Endocytosis
• Phagocytosis: pseudopods extend and engulf particles
• Pinocytosis: membrane folds inward, bringing in fluid and
dissolved substances
Table 4.2 Principal Differences between Prokaryotic and Eukaryotic Cells
Cytoplasm
• Cytosol: fluid portion of cytoplasm
• Cytoskeleton: microfilaments, intermediate filaments,
microtubules
• Provides support and shape and assists in transportation of
substances.
• Cytoplasmic streaming: movement of cytoplasm throughout cells
Ribosomes
• Protein synthesis
• 80S
• Membrane-bound: attached to ER
• Free: in cytoplasm
• 70S
• In chloroplasts and mitochondria
Organelles
• Nucleus: contains chromosomes
• The control center
• Most prominent internal organelle.
• Composed of:
• Nuclear envelope- 2 parallel membranes that are separated by a
space; also has small pores on the surface
• Nucleoplasm- inside space of the nucleus
• Nucleolus- granular mass; RNA synthesis and ribosomal subunit
collection area
• Lysosome: digestive enzymes
• Vacuole: brings food into cells and provides support
Figure 4.24c The eukaryotic nucleus.
Nuclear
pore(s)
Nuclear
envelope
Nucleolus
Chromatin
Endoplasmic Reticulum
•
•
•
•
•
Microscopic tunnel system made of cisternae
Functions:
Storage
Transportation
2 types:
• Rough endoplasmic reticulum (RER)- continuous with the nuclear
envelope; has ribosomes on surface; transports materials from
nucleus to the cytoplasm and is responsible for protein synthesis.
• Smooth endoplasmic reticulum (SER)- continuous with RER; no
ribosomes; is responsible for nutrient processing and synthesis
and storage of lipids, electrolytes, and other substances.
Figure 4.25 Rough endoplasmic reticulum and ribosomes.
Nuclear envelope
Ribosomes
Cisternae
Smooth ER Ribosomes
Rough ER
Golgi Complex
• Modify and secrete proteins
• 3 types of vesicles:
1.
2.
3.
Transitional- membrane bound packets of proteins that come
to the Golgi from the ER for modification.
Condensing- membrane bound packets of proteins that pinch
off from the Golgi and are used by organelles on the inside of
the cell
Secretory-membrane bound packets of proteins that pinch off
from the Golgi and are transported outside of the cell
Figure 4.26 Golgi complex.
Secretory
vesicles
Transfer
vesicles
Cisternae
Transport
vesicle from
rough ER
• Lysosomes
• Contain digestive
enzymes capable of
breaking down
substances
• Vacuoles
• Temporary storage
units
• Help to bring food into
cell
• Take in water
Figure 4.22b Eukaryotic cells showing typical structures.
Peroxisome
Nucleus
Vacuole
Animal cell, an
antibody-secreting
plasma cell
Chloroplast
Golgi complex
Mitochondrion
Plasma membrane
Nucleus
Cytoplasm
Nucleolus
Cell wall
Algal cell
(Tribonema vulgare)
Transmission electron micrographs of plant and animal cells.
Mitochondrion
Rough endoplasmic
reticulum
Lysosome
Mitochondria
• “Powerhouse” of the
cell
• Supplies most of the
energy for the cell
• Number varies
• Carries out cellular
respiration and
produces ATP.
Chloroplasts
• Algae
• Helps with
photosynthesis
Peroxisomes
• Similar to lysosomes.
• Store enzymes
• Catalase- breaks down hydrogen peroxide (H2O2)
Centrosome
• Composed of protein fibers and centrioles
• Plays critical role in cellular division
• Makes microtubles
Figure 10.2 A model of the origin of eukaryotes.
Endosymbiotic Theory
• What are the fine extensions on the protozoan shown on the
following slide?
• Larger bacteria engulfed smaller bacteria. Their relationship
became symbiotic.