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LECTURE PRESENTATIONS
For CAMPBELL BIOLOGY, NINTH EDITION
Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson
© 2011 Pearson Education, Inc.
Lectures by
Erin Barley
Kathleen Fitzpatrick
A Tour of the Cell
Chapter 6
Overview: The Fundamental Units of Life
• All organisms are made of cells
• Cell structure  function
• All cells are related by their descent from earlier
cells
© 2011 Pearson Education, Inc.
Microscopy
• Scientists use microscopes to visualize cells too
small to see with the naked eye
• In a light microscope (LM), visible light is
passed through a specimen and then through
glass lenses
• Lenses refract (bend) the light, so that the image
is magnified
© 2011 Pearson Education, Inc.
• Three important parameters of microscopy
– Magnification, the ratio of an object’s image size
to its real size
– Resolution, the measure of the clarity of the
image, or the minimum distance of two
distinguishable points
– Contrast, visible differences in parts of the
sample
© 2011 Pearson Education, Inc.
Figure 6.2 10 m
1 m
0.1 m
1 cm
1 mm
100 µm
10 µm
1 µm
100 nm
10 nm
1 nm
0.1 nm Atoms
Small molecules
Lipids
Proteins
Ribosomes
Viruses
Smallest bacteria
Mitochondrion
Most bacteria
Nucleus
Most plant and
animal cells
Human egg
Frog egg
Chicken egg
Length of some
nerve and
muscle cells
Human height
Unaidedeye
Lightmicroscopy
Electronmicroscopy
Super-
resolution
microscopy
Brightfield
(unstained specimen)
Brightfield
(stained specimen)
50µm
Confocal
Differential-interference-
contrast (Nomarski)
Fluorescence
10 µm
Deconvolution
Super-resolution
Scanning electron
microscopy (SEM)
Transmission electron
microscopy (TEM)
Cross section
of cilium
Longitudinal section
of cilium
Cilia
Electron Microscopy (EM)
1µm10µm50µm
2 µm
2 µm
Light Microscopy (LM)
Phase-contrast
Figure 6.3
• LMs can magnify effectively to about 1,000
times the size of the actual specimen
• Stain/contrast techniques reveal detail
• Most subcellular structures, including
organelles (membrane-enclosed
compartments), are too small to see with light
microscope
© 2011 Pearson Education, Inc.
• Two kinds of electron microscopes (EMs)
1. Scanning electron microscopes (SEMs) look
at surface of a specimen, take 3-D photos
2. Transmission electron microscopes (TEMs)
focus a beam of electrons through a thin slice of
a specimen
– TEMs are used to study the internal structure of cells
© 2011 Pearson Education, Inc.
– New techniques for labeling cells improve
resolution
© 2011 Pearson Education, Inc.
Cell Fractionation
• Cell fractionation – taking
cells apart to look at the
organelles & study function
• Centrifuges separate
organelles by fractionate
• Biochemistry and cytology
help correlate cell function
with structure
© 2011 Pearson Education, Inc.
Concept 6.2: Eukaryotic cells have internal
membranes that compartmentalize their
functions
• The basic structural and functional unit of every
organism is one of two types of cells: prokaryotic
or eukaryotic
• Only organisms of the domains Bacteria and
Archaea consist of prokaryotic cells
• Protists, fungi, animals, and plants all consist of
eukaryotic cells
© 2011 Pearson Education, Inc.
Comparing Prokaryotic and Eukaryotic
Cells
• Basic features of all cells
– Plasma membrane
– Semifluid substance called cytosol
– Chromosomes (carry genes)
– Ribosomes (make proteins)
© 2011 Pearson Education, Inc.
• Prokaryotic cells are characterized by having
– No nucleus
– DNA in an unbound region called the nucleoid
– No membrane-bound organelles
– Cytoplasm bound by the plasma membrane
© 2011 Pearson Education, Inc.
Fimbriae
Bacterial
chromosome
A typical
rod-shaped
bacterium
(a)
Nucleoid
Ribosomes
Plasma
membrane
Cell wall
Capsule
Flagella A thin section
through the
bacterium Bacillus
coagulans (TEM)
(b)
0.5 µm
Figure 6.5
Figure 6.5a
A thin section through the
bacterium Bacillus coagulans
(TEM)
(b)
0.5 µm
• Eukaryotic cells are characterized by having
– DNA in a nucleus that is bounded by a
membranous nuclear envelope
– Membrane-bound organelles
– Cytoplasm in the region between the plasma
membrane and nucleus
• Eukaryotic cells are generally much larger than
prokaryotic cells
© 2011 Pearson Education, Inc.
• The plasma membrane is a selective barrier
that allows sufficient passage of oxygen,
nutrients, and waste to service the volume of
every cell
• The general structure of a biological membrane
is a double layer of phospholipids
© 2011 Pearson Education, Inc.
Figure 6.6
Outside of cell
Inside of cell
0.1 µm
(a) TEM of a plasma
membrane
Hydrophilic
region
Hydrophobic
region
Hydrophilic
region
Carbohydrate side chains
ProteinsPhospholipid
(b) Structure of the plasma membrane
• Limits on the size of cells - The surface area to
volume ratio of a cell is critical
• As the surface area increases by a factor of n2
, the
volume increases by a factor of n3
• Small cells have a greater surface area relative to
volume
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Figure 6.8a
ENDOPLASMIC RETICULUM (ER)
Rough
ER
Smooth
ER
Nuclear
envelope
Nucleolus
Chromatin
Plasma
membrane
Ribosomes
Golgi apparatus
LysosomeMitochondrion
Peroxisome
Microvilli
Microtubules
Intermediate filaments
Microfilaments
Centrosome
CYTOSKELETON:
Flagellum NUCLEUS
NUCLEUS
Nuclear
envelope
Nucleolus
Chromatin
Golgi
apparatus
Mitochondrion
Peroxisome
Plasma membrane
Cell wall
Wall of adjacent cell
Plasmodesmata
Chloroplast
Microtubules
Intermediate
filaments
Microfilaments
CYTOSKELETON
Central vacuole
Ribosomes
Smooth
endoplasmic
reticulum
Rough
endoplasmic
reticulum
Figure 6.8c
Concept 6.3: The eukaryotic cell’s genetic
instructions are housed in the nucleus and
carried out by the ribosomes
• The nucleus contains most of the DNA in a
eukaryotic cell
• Ribosomes use the information from the DNA to
make proteins
© 2011 Pearson Education, Inc.
The Nucleus: Information Central
• The nucleus contains most of the cell’s genes
and is usually the most conspicuous organelle
• The nuclear envelope encloses the nucleus,
separating it from the cytoplasm
• The nuclear membrane is a double membrane;
each membrane consists of a lipid bilayer
© 2011 Pearson Education, Inc.
Nucleus
Rough ER
Nucleolus
Chromatin
Nuclear envelope:
Inner membrane
Outer membrane
Nuclear pore
Ribosome
Pore
complex
Close-up
of nuclear
envelope
Surface of nuclear
envelope
Pore complexes (TEM)
0.25µm
1µm
Nuclear lamina (TEM)
Chromatin
1 µm
Figure 6.9
Nucleus
Rough ER
Nucleolus
Chromatin
Nuclear envelope:
Inner membrane
Outer membrane
Nuclear pore
Chromatin
Ribosome
Pore
complex
Close-up
of nuclear
envelope
Figure 6.9a
Figure 6.9b
Nuclear envelope:
Inner membrane
Outer membrane
Nuclear pore
Surface of nuclear
envelope
1 µm
Figure 6.9c
Pore complexes (TEM)
0.25µm
Figure 6.9d
1µm
Nuclear lamina (TEM)
• Pores regulate the entry and exit of molecules
from the nucleus
• The shape of the nucleus is maintained by the
nuclear lamina, which is composed of protein
© 2011 Pearson Education, Inc.
• In the nucleus, DNA is organized into discrete
units called chromosomes
• Each chromosome is composed of a single DNA
molecule associated with proteins
• The DNA and proteins of chromosomes are
together called chromatin
• Chromatin condenses to form discrete
chromosomes as a cell prepares to divide
• The nucleolus is located within the nucleus and
is the site of ribosomal RNA (rRNA) synthesis
© 2011 Pearson Education, Inc.
Ribosomes: Protein Factories
• Ribosomes are particles made of ribosomal
RNA and protein
• Ribosomes carry out protein synthesis in two
locations
– In the cytosol (free ribosomes)
– On the outside of the endoplasmic reticulum or
the nuclear envelope (bound ribosomes)
© 2011 Pearson Education, Inc.
Figure 6.10
0.25 µm
Free ribosomes in cytosol
Endoplasmic reticulum (ER)
Ribosomes bound to ER
Large
subunit
Small
subunit
Diagram of a ribosome
TEM showing ER and
ribosomes
Concept 6.4: The endomembrane system
regulates protein traffic and performs
metabolic functions in the cell
• Components of the endomembrane system
– Nuclear envelope
– Endoplasmic reticulum
– Golgi apparatus
– Lysosomes
– Vacuoles
– Plasma membrane
• These components are either continuous or
connected via transfer by vesicles
© 2011 Pearson Education, Inc.
The Endoplasmic Reticulum: Biosynthetic
Factory
• The endoplasmic reticulum (ER) accounts for
more than half of the total membrane in many
eukaryotic cells
• The ER membrane is continuous with the
nuclear envelope
• There are two distinct regions of ER
– Smooth ER, which lacks ribosomes
– Rough ER, surface is studded with ribosomes
© 2011 Pearson Education, Inc.
Figure 6.11 Smooth ER
Rough ER
ER lumen
Cisternae
Ribosomes
Smooth ER
Transport vesicle
Transitional ER
Rough ER
200 nm
Nuclear
envelope
Figure 6.11a
Smooth ER
Rough ER
Cisternae
Ribosomes
Transport vesicle
Transitional ER
Nuclear
envelope
ER lumen
Functions of Smooth ER
• The smooth ER
– Synthesizes lipids
– Metabolizes carbohydrates
– Detoxifies drugs and poisons
– Stores calcium ions
© 2011 Pearson Education, Inc.
Functions of Rough ER
• The rough ER
– Has bound ribosomes, which secrete
glycoproteins (proteins covalently bonded to
carbohydrates)
– Distributes transport vesicles, proteins
surrounded by membranes
– Is a membrane factory for the cell
© 2011 Pearson Education, Inc.
• The Golgi apparatus consists of flattened
membranous sacs called cisternae
• Functions of the Golgi apparatus
– Modifies products of the ER
– Manufactures certain macromolecules
– Sorts and packages materials into transport
vesicles
The Golgi Apparatus: Shipping and
Receiving Center
© 2011 Pearson Education, Inc.
Figure 6.12
cis face
(“receiving” side of
Golgi apparatus)
trans face
(“shipping” side of
Golgi apparatus)
0.1 µm
TEM of Golgi apparatus
Cisternae
Figure 6.12a
TEM of Golgi apparatus
0.1 µm
Lysosomes: Digestive Compartments
• A lysosome is a membranous sac of
hydrolytic enzymes that can digest
macromolecules
• Lysosomal enzymes can hydrolyze proteins,
fats, polysaccharides, and nucleic acids
• Lysosomal enzymes work best in the acidic
environment inside the lysosome
© 2011 Pearson Education, Inc.
Animation: Lysosome Formation
• Some types of cell can engulf another cell by
phagocytosis; this forms a food vacuole
• A lysosome fuses with the food vacuole and
digests the molecules
• Lysosomes also use enzymes to recycle the
cell’s own organelles and macromolecules, a
process called autophagy
© 2011 Pearson Education, Inc.
Figure 6.13
Nucleus
Lysosome
1 µm
Digestive
enzymes
Digestion
Food vacuole
Lysosome
Plasma membrane
(a) Phagocytosis
Vesicle containing
two damaged
organelles
1 µm
Mitochondrion
fragment
Peroxisome
fragment
(b) Autophagy
Peroxisome
Vesicle
Mitochondrion
Lysosome
Digestion
Figure 6.13a
Nucleus
Lysosome
1 µm
Digestive
enzymes
Digestion
Food vacuole
Lysosome
Plasma membrane
(a) Phagocytosis
Figure 6.13b
Vesicle containing
two damaged
organelles
1 µm
Mitochondrion
fragment
Peroxisome
fragment
Peroxisome
Vesicle
Mitochondrion
Lysosome
Digestion
(b) Autophagy
Vacuoles: Diverse Maintenance
Compartments
• A plant cell or fungal cell may have one or
several vacuoles, derived from endoplasmic
reticulum and Golgi apparatus
© 2011 Pearson Education, Inc.
• Food vacuoles are formed by phagocytosis
• Contractile vacuoles, found in many freshwater
protists, pump excess water out of cells
• Central vacuoles, found in many mature plant
cells, hold organic compounds and water
© 2011 Pearson Education, Inc.
Video: Paramecium Vacuole
Figure 6.14
Central vacuole
Cytosol
Nucleus
Cell wall
Chloroplast
Central
vacuole
5 µm
Figure 6.15-1
Smooth ER
Nucleus
Rough ER
Plasma
membrane
Figure 6.15-2
Smooth ER
Nucleus
Rough ER
Plasma
membrane
cis Golgi
trans Golgi
Figure 6.15-3
Smooth ER
Nucleus
Rough ER
Plasma
membrane
cis Golgi
trans Golgi
Concept 6.5: Mitochondria and chloroplasts
change energy from one form to another
• Mitochondria are the sites of cellular respiration,
a metabolic process that uses oxygen to
generate ATP
• Chloroplasts, found in plants and algae, are the
sites of photosynthesis
• Peroxisomes are oxidative organelles
© 2011 Pearson Education, Inc.
• Mitochondria and chloroplasts have similarities
with bacteria
– Enveloped by a double membrane
– Contain free ribosomes and circular DNA
molecules
– Grow and reproduce somewhat independently
in cells
© 2011 Pearson Education, Inc.
The Evolutionary Origins of Mitochondria
and Chloroplasts
Mitochondria: Chemical Energy Conversion
• Mitochondria are in nearly all eukaryotic cells
• They have a smooth outer membrane and an
inner membrane folded into cristae
• The inner membrane creates two compartments:
intermembrane space and mitochondrial matrix
• Some metabolic steps of cellular respiration are
catalyzed in the mitochondrial matrix
• Cristae present a large surface area for enzymes
that synthesize ATP
© 2011 Pearson Education, Inc.
Figure 6.17
Intermembrane space
Outer
membrane
DNA
Inner
membrane
Cristae
Matrix
Free
ribosomes
in the
mitochondrial
matrix
(a) Diagram and TEM of mitochondrion (b) Network of mitochondria in a protist
cell (LM)
0.1 µm
Mitochondrial
DNA
Nuclear DNA
Mitochondria
10 µm
Figure 6.17a
Intermembrane space
Outer
DNA
Inner
membrane
Cristae
Matrix
Free
ribosomes
in the
mitochondrial
matrix
(a) Diagram and TEM of mitochondrion
0.1 µm
membrane
• Chloroplast structure includes
– Thylakoids, membranous sacs, stacked to
form a granum
– Stroma, the internal fluid
• The chloroplast is one of a group of plant
organelles, called plastids
© 2011 Pearson Education, Inc.
Figure 6.18
Ribosomes
Stroma
Inner and outer
membranes
Granum
1 µmIntermembrane spaceThylakoid
(a) Diagram and TEM of chloroplast (b) Chloroplasts in an algal cell
Chloroplasts
(red)
50 µm
DNA
Peroxisomes: Oxidation
• Peroxisomes are specialized metabolic
compartments bounded by a single membrane
• Peroxisomes produce hydrogen peroxide and
convert it to water
• Peroxisomes perform reactions with many
different functions
• How peroxisomes are related to other organelles
is still unknown
© 2011 Pearson Education, Inc.
Concept 6.6: The cytoskeleton is a network
of fibers that organizes structures and
activities in the cell
• The cytoskeleton is a network of fibers
extending throughout the cytoplasm
• It organizes the cell’s structures and activities,
anchoring many organelles
• It is composed of three types of molecular
structures
– Microtubules
– Microfilaments
– Intermediate filaments
© 2011 Pearson Education, Inc.
Figure 6.20
10µm
Roles of the Cytoskeleton:
Support and Motility
• The cytoskeleton helps to support the cell and
maintain its shape
• It interacts with motor proteins to produce
motility
• Inside the cell, vesicles can travel along
“monorails” provided by the cytoskeleton
• Recent evidence suggests that the cytoskeleton
may help regulate biochemical activities
© 2011 Pearson Education, Inc.
Figure 6.21
ATP
Vesicle
(a)
Motor protein
(ATP powered)
Microtubule
of cytoskeleton
Receptor for
motor protein
0.25 µmVesiclesMicrotubule
(b)
Components of the Cytoskeleton
• Three main types of fibers make up the
cytoskeleton
– Microtubules are the thickest of the three
components of the cytoskeleton
– Microfilaments, also called actin filaments, are
the thinnest components
– Intermediate filaments are fibers with
diameters in a middle range
© 2011 Pearson Education, Inc.
Tubulin dimer
25 nm
α β
Column of tubulin dimers
10 µm
Table 6.1a
10 µm
Actin subunit
7 nm
Table 6.1b
5 µm
Keratin proteins
Fibrous subunit (keratins
coiled together)
8−12 nm
Table 6.1c
Microtubules
• Microtubules are hollow rods about 25 nm in
diameter and about 200 nm to 25 microns long
• Functions of microtubules
– Shaping the cell
– Guiding movement of organelles
– Separating chromosomes during cell division
© 2011 Pearson Education, Inc.
Centrosomes and Centrioles
• In many cells, microtubules grow out from a
centrosome near the nucleus
• The centrosome is a “microtubule-organizing
center”
• In animal cells, the centrosome has a pair of
centrioles, each with nine triplets of
microtubules arranged in a ring
© 2011 Pearson Education, Inc.
Centrosome
Longitudinal
section of
one centriole
Centrioles
Microtubule
0.25 µm
Microtubules Cross section
of the other centriole
Figure 6.22
Cilia and Flagella
• Microtubules control the beating of cilia and
flagella, locomotor appendages of some cells
• Cilia and flagella differ in their beating patterns
© 2011 Pearson Education, Inc.
Video: Chlamydomonas
Video: Paramecium Cilia
Direction of swimming
(b) Motion of cilia
Direction of organism’s movement
Power stroke Recovery stroke
(a) Motion of flagella
5 µm
15 µm
Figure 6.23
• Cilia and flagella share a common structure
– A core of microtubules sheathed by the plasma
membrane
– A basal body that anchors the cilium or
flagellum
– A motor protein called dynein, which drives the
bending movements of a cilium or flagellum
© 2011 Pearson Education, Inc.
Animation: Cilia and Flagella
Microtubules
Plasma
membrane
Basal body
Longitudinal section
of motile cilium
(a)
0.5 µm 0.1 µm
0.1 µm
(b) Cross section of
motile cilium
Outer microtubule
doublet
Dynein proteins
Central
microtubule
Radial
spoke
Cross-linking
proteins between
outer doublets
Plasma membrane
Triplet
(c) Cross section of
basal body
Figure 6.24
Figure 6.24a
Microtubules
Plasma
membrane
Basal body
Longitudinal section
of motile cilium
0.5 µm
(a)
Figure 6.24b
0.1 µm
(b) Cross section of
motile cilium
Outer microtubule
doublet
Dynein proteins
Central
microtubule
Radial
spoke
Cross-linking
proteins between
outer doublets
Plasma membrane
Figure 6.24ba
0.1 µm
(b) Cross section of
motile cilium
Outer microtubule
doublet
Dynein proteins
Central
microtubule
Radial
spoke
Cross-linking
proteins between
outer doublets
Figure 6.24c
0.1 µm
Triplet
(c) Cross section of
basal body
• How dynein “walking” moves flagella and cilia
− Dynein arms alternately grab, move, and release
the outer microtubules
– Protein cross-links limit sliding
– Forces exerted by dynein arms cause doublets to
curve, bending the cilium or flagellum
© 2011 Pearson Education, Inc.
Figure 6.25 Microtubule
doublets
Dynein protein
ATP
(a) Effect of unrestrained dynein movement
Cross-linking proteins
between outer doublets
ATP
Anchorage
in cell
(b) Effect of cross-linking proteins
(c) Wavelike motion
1
2
3
Microtubule
doublets
Dynein protein
ATP
(a) Effect of unrestrained dynein movement
Figure 6.25a
Figure 6.25b
Cross-linking proteins
between outer doublets
ATP
Anchorage
in cell
(b) Effect of cross-linking proteins (c) Wavelike motion
31
2
Microfilaments (Actin Filaments)
• Microfilaments are solid rods about 7 nm in
diameter, built as a twisted double chain of actin
subunits
• The structural role of microfilaments is to bear
tension, resisting pulling forces within the cell
• They form a 3-D network called the cortex just
inside the plasma membrane to help support the
cell’s shape
• Bundles of microfilaments make up the core of
microvilli of intestinal cells
© 2011 Pearson Education, Inc.
Figure 6.26
Microvillus
Plasma membrane
Microfilaments (actin
filaments)
Intermediate filaments
0.25 µm
• Microfilaments that function in cellular motility
contain the protein myosin in addition to actin
• In muscle cells, thousands of actin filaments are
arranged parallel to one another
• Thicker filaments composed of myosin
interdigitate with the thinner actin fibers
© 2011 Pearson Education, Inc.
Figure 6.27
Muscle cell
Actin
filament
Myosin
Myosin
filament
head
(a) Myosin motors in muscle cell contraction
0.5 µm
100 µm
Cortex (outer cytoplasm):
gel with actin network
Inner cytoplasm: sol
with actin subunits
(b) Amoeboid movement
Extending
pseudopodium
30 µm
(c) Cytoplasmic streaming in plant cells
Chloroplast
Figure 6.27a
Muscle cell
Actin
filament
Myosin
Myosin
filament
(a) Myosin motors in muscle cell contraction
0.5 µm
head
Figure 6.27b
100 µm
Cortex (outer cytoplasm):
gel with actin network
Inner cytoplasm: sol
with actin subunits
(b) Amoeboid movement
Extending
pseudopodium
Figure 6.27c
30 µm
(c) Cytoplasmic streaming in plant cells
Chloroplast
Intermediate Filaments
• Intermediate filaments range in diameter from
8–12 nanometers, larger than microfilaments but
smaller than microtubules
• They support cell shape and fix organelles in
place
• Intermediate filaments are more permanent
cytoskeleton fixtures than the other two classes
© 2011 Pearson Education, Inc.
Concept 6.7: Extracellular components and
connections between cells help coordinate
cellular activities
• Most cells synthesize and secrete materials that
are external to the plasma membrane
• These extracellular structures include
– Cell walls of plants
– The extracellular matrix (ECM) of animal cells
– Intercellular junctions
© 2011 Pearson Education, Inc.
Cell Walls of Plants
• The cell wall is an extracellular structure that
distinguishes plant cells from animal cells
• Prokaryotes, fungi, and some protists also have
cell walls
• The cell wall protects the plant cell, maintains its
shape, and prevents excessive uptake of water
• Plant cell walls are made of cellulose fibers
embedded in other polysaccharides and protein
© 2011 Pearson Education, Inc.
The Extracellular Matrix (ECM) of Animal
Cells
• Animal cells lack cell walls but are covered by an
elaborate extracellular matrix (ECM)
• The ECM is made up of glycoproteins such as
collagen, proteoglycans, and fibronectin
• ECM proteins bind to receptor proteins in the
plasma membrane called integrins
© 2011 Pearson Education, Inc.
Figure 6.30
EXTRACELLULAR FLUID
Collagen
Fibronectin
Plasma
membrane
Micro-
filaments
CYTOPLASM
Integrins
Proteoglycan
complex
Polysaccharide
molecule
Carbo-
hydrates
Core
protein
Proteoglycan
molecule
Proteoglycan complex
Figure 6.30a
EXTRACELLULAR FLUIDCollagen
Fibronectin
Plasma
membrane
Micro-
filaments
CYTOPLASM
Integrins
Proteoglycan
complex
Figure 6.30b
Polysaccharide
molecule
Carbohydrates
Core
protein
Proteoglycan
molecule
Proteoglycan complex
Cell Junctions
• Neighboring cells in tissues, organs, or organ
systems often adhere, interact, and
communicate through direct physical contact
• Intercellular junctions facilitate this contact
• There are several types of intercellular junctions
– Plasmodesmata
– Tight junctions
– Desmosomes
– Gap junctions
© 2011 Pearson Education, Inc.
Plasmodesmata in Plant Cells
• Plasmodesmata are channels that perforate
plant cell walls
• Through plasmodesmata, water and small
solutes (and sometimes proteins and RNA) can
pass from cell to cell
© 2011 Pearson Education, Inc.
Figure 6.31
Interior
of cell
Interior
of cell
0.5 µm Plasmodesmata Plasma membranes
Cell walls
Tight Junctions, Desmosomes, and Gap
Junctions in Animal Cells
• At tight junctions, membranes of neighboring
cells are pressed together, preventing leakage of
extracellular fluid
• Desmosomes (anchoring junctions) fasten cells
together into strong sheets
• Gap junctions (communicating junctions) provide
cytoplasmic channels between adjacent cells
© 2011 Pearson Education, Inc.
Figure 6.32
Tight junctions prevent
fluid from moving
across a layer of cells
Tight junction
Tight junction
TEM
0.5 µm
TEM
1 µm
TEM
0.1 µm
Extracellular
matrixPlasma membranes
of adjacent cells
Space
between cells
Ions or small
molecules
Desmosome
Intermediate
filaments
Gap
junction
Tight junctions prevent
fluid from moving
across a layer of cells
Extracellular
matrix
Plasma membranes
of adjacent cells
Space
between cells
Ions or small
molecules
Desmosome
Intermediate
filaments
Tight junction
Gap
junction
Figure 6.32a

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Cell Structure and Function Lecture

  • 1. LECTURE PRESENTATIONS For CAMPBELL BIOLOGY, NINTH EDITION Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson © 2011 Pearson Education, Inc. Lectures by Erin Barley Kathleen Fitzpatrick A Tour of the Cell Chapter 6
  • 2. Overview: The Fundamental Units of Life • All organisms are made of cells • Cell structure  function • All cells are related by their descent from earlier cells © 2011 Pearson Education, Inc.
  • 3. Microscopy • Scientists use microscopes to visualize cells too small to see with the naked eye • In a light microscope (LM), visible light is passed through a specimen and then through glass lenses • Lenses refract (bend) the light, so that the image is magnified © 2011 Pearson Education, Inc.
  • 4. • Three important parameters of microscopy – Magnification, the ratio of an object’s image size to its real size – Resolution, the measure of the clarity of the image, or the minimum distance of two distinguishable points – Contrast, visible differences in parts of the sample © 2011 Pearson Education, Inc.
  • 5. Figure 6.2 10 m 1 m 0.1 m 1 cm 1 mm 100 µm 10 µm 1 µm 100 nm 10 nm 1 nm 0.1 nm Atoms Small molecules Lipids Proteins Ribosomes Viruses Smallest bacteria Mitochondrion Most bacteria Nucleus Most plant and animal cells Human egg Frog egg Chicken egg Length of some nerve and muscle cells Human height Unaidedeye Lightmicroscopy Electronmicroscopy Super- resolution microscopy
  • 6. Brightfield (unstained specimen) Brightfield (stained specimen) 50µm Confocal Differential-interference- contrast (Nomarski) Fluorescence 10 µm Deconvolution Super-resolution Scanning electron microscopy (SEM) Transmission electron microscopy (TEM) Cross section of cilium Longitudinal section of cilium Cilia Electron Microscopy (EM) 1µm10µm50µm 2 µm 2 µm Light Microscopy (LM) Phase-contrast Figure 6.3
  • 7. • LMs can magnify effectively to about 1,000 times the size of the actual specimen • Stain/contrast techniques reveal detail • Most subcellular structures, including organelles (membrane-enclosed compartments), are too small to see with light microscope © 2011 Pearson Education, Inc.
  • 8. • Two kinds of electron microscopes (EMs) 1. Scanning electron microscopes (SEMs) look at surface of a specimen, take 3-D photos 2. Transmission electron microscopes (TEMs) focus a beam of electrons through a thin slice of a specimen – TEMs are used to study the internal structure of cells © 2011 Pearson Education, Inc.
  • 9. – New techniques for labeling cells improve resolution © 2011 Pearson Education, Inc.
  • 10. Cell Fractionation • Cell fractionation – taking cells apart to look at the organelles & study function • Centrifuges separate organelles by fractionate • Biochemistry and cytology help correlate cell function with structure © 2011 Pearson Education, Inc.
  • 11. Concept 6.2: Eukaryotic cells have internal membranes that compartmentalize their functions • The basic structural and functional unit of every organism is one of two types of cells: prokaryotic or eukaryotic • Only organisms of the domains Bacteria and Archaea consist of prokaryotic cells • Protists, fungi, animals, and plants all consist of eukaryotic cells © 2011 Pearson Education, Inc.
  • 12. Comparing Prokaryotic and Eukaryotic Cells • Basic features of all cells – Plasma membrane – Semifluid substance called cytosol – Chromosomes (carry genes) – Ribosomes (make proteins) © 2011 Pearson Education, Inc.
  • 13. • Prokaryotic cells are characterized by having – No nucleus – DNA in an unbound region called the nucleoid – No membrane-bound organelles – Cytoplasm bound by the plasma membrane © 2011 Pearson Education, Inc.
  • 14. Fimbriae Bacterial chromosome A typical rod-shaped bacterium (a) Nucleoid Ribosomes Plasma membrane Cell wall Capsule Flagella A thin section through the bacterium Bacillus coagulans (TEM) (b) 0.5 µm Figure 6.5
  • 15. Figure 6.5a A thin section through the bacterium Bacillus coagulans (TEM) (b) 0.5 µm
  • 16. • Eukaryotic cells are characterized by having – DNA in a nucleus that is bounded by a membranous nuclear envelope – Membrane-bound organelles – Cytoplasm in the region between the plasma membrane and nucleus • Eukaryotic cells are generally much larger than prokaryotic cells © 2011 Pearson Education, Inc.
  • 17. • The plasma membrane is a selective barrier that allows sufficient passage of oxygen, nutrients, and waste to service the volume of every cell • The general structure of a biological membrane is a double layer of phospholipids © 2011 Pearson Education, Inc.
  • 18. Figure 6.6 Outside of cell Inside of cell 0.1 µm (a) TEM of a plasma membrane Hydrophilic region Hydrophobic region Hydrophilic region Carbohydrate side chains ProteinsPhospholipid (b) Structure of the plasma membrane
  • 19. • Limits on the size of cells - The surface area to volume ratio of a cell is critical • As the surface area increases by a factor of n2 , the volume increases by a factor of n3 • Small cells have a greater surface area relative to volume Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
  • 20.
  • 21. Figure 6.8a ENDOPLASMIC RETICULUM (ER) Rough ER Smooth ER Nuclear envelope Nucleolus Chromatin Plasma membrane Ribosomes Golgi apparatus LysosomeMitochondrion Peroxisome Microvilli Microtubules Intermediate filaments Microfilaments Centrosome CYTOSKELETON: Flagellum NUCLEUS
  • 22. NUCLEUS Nuclear envelope Nucleolus Chromatin Golgi apparatus Mitochondrion Peroxisome Plasma membrane Cell wall Wall of adjacent cell Plasmodesmata Chloroplast Microtubules Intermediate filaments Microfilaments CYTOSKELETON Central vacuole Ribosomes Smooth endoplasmic reticulum Rough endoplasmic reticulum Figure 6.8c
  • 23. Concept 6.3: The eukaryotic cell’s genetic instructions are housed in the nucleus and carried out by the ribosomes • The nucleus contains most of the DNA in a eukaryotic cell • Ribosomes use the information from the DNA to make proteins © 2011 Pearson Education, Inc.
  • 24. The Nucleus: Information Central • The nucleus contains most of the cell’s genes and is usually the most conspicuous organelle • The nuclear envelope encloses the nucleus, separating it from the cytoplasm • The nuclear membrane is a double membrane; each membrane consists of a lipid bilayer © 2011 Pearson Education, Inc.
  • 25. Nucleus Rough ER Nucleolus Chromatin Nuclear envelope: Inner membrane Outer membrane Nuclear pore Ribosome Pore complex Close-up of nuclear envelope Surface of nuclear envelope Pore complexes (TEM) 0.25µm 1µm Nuclear lamina (TEM) Chromatin 1 µm Figure 6.9
  • 26. Nucleus Rough ER Nucleolus Chromatin Nuclear envelope: Inner membrane Outer membrane Nuclear pore Chromatin Ribosome Pore complex Close-up of nuclear envelope Figure 6.9a
  • 27. Figure 6.9b Nuclear envelope: Inner membrane Outer membrane Nuclear pore Surface of nuclear envelope 1 µm
  • 28. Figure 6.9c Pore complexes (TEM) 0.25µm
  • 30. • Pores regulate the entry and exit of molecules from the nucleus • The shape of the nucleus is maintained by the nuclear lamina, which is composed of protein © 2011 Pearson Education, Inc.
  • 31. • In the nucleus, DNA is organized into discrete units called chromosomes • Each chromosome is composed of a single DNA molecule associated with proteins • The DNA and proteins of chromosomes are together called chromatin • Chromatin condenses to form discrete chromosomes as a cell prepares to divide • The nucleolus is located within the nucleus and is the site of ribosomal RNA (rRNA) synthesis © 2011 Pearson Education, Inc.
  • 32. Ribosomes: Protein Factories • Ribosomes are particles made of ribosomal RNA and protein • Ribosomes carry out protein synthesis in two locations – In the cytosol (free ribosomes) – On the outside of the endoplasmic reticulum or the nuclear envelope (bound ribosomes) © 2011 Pearson Education, Inc.
  • 33. Figure 6.10 0.25 µm Free ribosomes in cytosol Endoplasmic reticulum (ER) Ribosomes bound to ER Large subunit Small subunit Diagram of a ribosome TEM showing ER and ribosomes
  • 34. Concept 6.4: The endomembrane system regulates protein traffic and performs metabolic functions in the cell • Components of the endomembrane system – Nuclear envelope – Endoplasmic reticulum – Golgi apparatus – Lysosomes – Vacuoles – Plasma membrane • These components are either continuous or connected via transfer by vesicles © 2011 Pearson Education, Inc.
  • 35. The Endoplasmic Reticulum: Biosynthetic Factory • The endoplasmic reticulum (ER) accounts for more than half of the total membrane in many eukaryotic cells • The ER membrane is continuous with the nuclear envelope • There are two distinct regions of ER – Smooth ER, which lacks ribosomes – Rough ER, surface is studded with ribosomes © 2011 Pearson Education, Inc.
  • 36. Figure 6.11 Smooth ER Rough ER ER lumen Cisternae Ribosomes Smooth ER Transport vesicle Transitional ER Rough ER 200 nm Nuclear envelope
  • 37. Figure 6.11a Smooth ER Rough ER Cisternae Ribosomes Transport vesicle Transitional ER Nuclear envelope ER lumen
  • 38. Functions of Smooth ER • The smooth ER – Synthesizes lipids – Metabolizes carbohydrates – Detoxifies drugs and poisons – Stores calcium ions © 2011 Pearson Education, Inc.
  • 39. Functions of Rough ER • The rough ER – Has bound ribosomes, which secrete glycoproteins (proteins covalently bonded to carbohydrates) – Distributes transport vesicles, proteins surrounded by membranes – Is a membrane factory for the cell © 2011 Pearson Education, Inc.
  • 40. • The Golgi apparatus consists of flattened membranous sacs called cisternae • Functions of the Golgi apparatus – Modifies products of the ER – Manufactures certain macromolecules – Sorts and packages materials into transport vesicles The Golgi Apparatus: Shipping and Receiving Center © 2011 Pearson Education, Inc.
  • 41. Figure 6.12 cis face (“receiving” side of Golgi apparatus) trans face (“shipping” side of Golgi apparatus) 0.1 µm TEM of Golgi apparatus Cisternae
  • 42. Figure 6.12a TEM of Golgi apparatus 0.1 µm
  • 43. Lysosomes: Digestive Compartments • A lysosome is a membranous sac of hydrolytic enzymes that can digest macromolecules • Lysosomal enzymes can hydrolyze proteins, fats, polysaccharides, and nucleic acids • Lysosomal enzymes work best in the acidic environment inside the lysosome © 2011 Pearson Education, Inc. Animation: Lysosome Formation
  • 44. • Some types of cell can engulf another cell by phagocytosis; this forms a food vacuole • A lysosome fuses with the food vacuole and digests the molecules • Lysosomes also use enzymes to recycle the cell’s own organelles and macromolecules, a process called autophagy © 2011 Pearson Education, Inc.
  • 45. Figure 6.13 Nucleus Lysosome 1 µm Digestive enzymes Digestion Food vacuole Lysosome Plasma membrane (a) Phagocytosis Vesicle containing two damaged organelles 1 µm Mitochondrion fragment Peroxisome fragment (b) Autophagy Peroxisome Vesicle Mitochondrion Lysosome Digestion
  • 46. Figure 6.13a Nucleus Lysosome 1 µm Digestive enzymes Digestion Food vacuole Lysosome Plasma membrane (a) Phagocytosis
  • 47. Figure 6.13b Vesicle containing two damaged organelles 1 µm Mitochondrion fragment Peroxisome fragment Peroxisome Vesicle Mitochondrion Lysosome Digestion (b) Autophagy
  • 48. Vacuoles: Diverse Maintenance Compartments • A plant cell or fungal cell may have one or several vacuoles, derived from endoplasmic reticulum and Golgi apparatus © 2011 Pearson Education, Inc.
  • 49. • Food vacuoles are formed by phagocytosis • Contractile vacuoles, found in many freshwater protists, pump excess water out of cells • Central vacuoles, found in many mature plant cells, hold organic compounds and water © 2011 Pearson Education, Inc. Video: Paramecium Vacuole
  • 50. Figure 6.14 Central vacuole Cytosol Nucleus Cell wall Chloroplast Central vacuole 5 µm
  • 52. Figure 6.15-2 Smooth ER Nucleus Rough ER Plasma membrane cis Golgi trans Golgi
  • 53. Figure 6.15-3 Smooth ER Nucleus Rough ER Plasma membrane cis Golgi trans Golgi
  • 54. Concept 6.5: Mitochondria and chloroplasts change energy from one form to another • Mitochondria are the sites of cellular respiration, a metabolic process that uses oxygen to generate ATP • Chloroplasts, found in plants and algae, are the sites of photosynthesis • Peroxisomes are oxidative organelles © 2011 Pearson Education, Inc.
  • 55. • Mitochondria and chloroplasts have similarities with bacteria – Enveloped by a double membrane – Contain free ribosomes and circular DNA molecules – Grow and reproduce somewhat independently in cells © 2011 Pearson Education, Inc. The Evolutionary Origins of Mitochondria and Chloroplasts
  • 56. Mitochondria: Chemical Energy Conversion • Mitochondria are in nearly all eukaryotic cells • They have a smooth outer membrane and an inner membrane folded into cristae • The inner membrane creates two compartments: intermembrane space and mitochondrial matrix • Some metabolic steps of cellular respiration are catalyzed in the mitochondrial matrix • Cristae present a large surface area for enzymes that synthesize ATP © 2011 Pearson Education, Inc.
  • 57. Figure 6.17 Intermembrane space Outer membrane DNA Inner membrane Cristae Matrix Free ribosomes in the mitochondrial matrix (a) Diagram and TEM of mitochondrion (b) Network of mitochondria in a protist cell (LM) 0.1 µm Mitochondrial DNA Nuclear DNA Mitochondria 10 µm
  • 58. Figure 6.17a Intermembrane space Outer DNA Inner membrane Cristae Matrix Free ribosomes in the mitochondrial matrix (a) Diagram and TEM of mitochondrion 0.1 µm membrane
  • 59. • Chloroplast structure includes – Thylakoids, membranous sacs, stacked to form a granum – Stroma, the internal fluid • The chloroplast is one of a group of plant organelles, called plastids © 2011 Pearson Education, Inc.
  • 60. Figure 6.18 Ribosomes Stroma Inner and outer membranes Granum 1 µmIntermembrane spaceThylakoid (a) Diagram and TEM of chloroplast (b) Chloroplasts in an algal cell Chloroplasts (red) 50 µm DNA
  • 61. Peroxisomes: Oxidation • Peroxisomes are specialized metabolic compartments bounded by a single membrane • Peroxisomes produce hydrogen peroxide and convert it to water • Peroxisomes perform reactions with many different functions • How peroxisomes are related to other organelles is still unknown © 2011 Pearson Education, Inc.
  • 62. Concept 6.6: The cytoskeleton is a network of fibers that organizes structures and activities in the cell • The cytoskeleton is a network of fibers extending throughout the cytoplasm • It organizes the cell’s structures and activities, anchoring many organelles • It is composed of three types of molecular structures – Microtubules – Microfilaments – Intermediate filaments © 2011 Pearson Education, Inc.
  • 64. Roles of the Cytoskeleton: Support and Motility • The cytoskeleton helps to support the cell and maintain its shape • It interacts with motor proteins to produce motility • Inside the cell, vesicles can travel along “monorails” provided by the cytoskeleton • Recent evidence suggests that the cytoskeleton may help regulate biochemical activities © 2011 Pearson Education, Inc.
  • 65. Figure 6.21 ATP Vesicle (a) Motor protein (ATP powered) Microtubule of cytoskeleton Receptor for motor protein 0.25 µmVesiclesMicrotubule (b)
  • 66. Components of the Cytoskeleton • Three main types of fibers make up the cytoskeleton – Microtubules are the thickest of the three components of the cytoskeleton – Microfilaments, also called actin filaments, are the thinnest components – Intermediate filaments are fibers with diameters in a middle range © 2011 Pearson Education, Inc.
  • 67. Tubulin dimer 25 nm α β Column of tubulin dimers 10 µm Table 6.1a
  • 68. 10 µm Actin subunit 7 nm Table 6.1b
  • 69. 5 µm Keratin proteins Fibrous subunit (keratins coiled together) 8−12 nm Table 6.1c
  • 70. Microtubules • Microtubules are hollow rods about 25 nm in diameter and about 200 nm to 25 microns long • Functions of microtubules – Shaping the cell – Guiding movement of organelles – Separating chromosomes during cell division © 2011 Pearson Education, Inc.
  • 71. Centrosomes and Centrioles • In many cells, microtubules grow out from a centrosome near the nucleus • The centrosome is a “microtubule-organizing center” • In animal cells, the centrosome has a pair of centrioles, each with nine triplets of microtubules arranged in a ring © 2011 Pearson Education, Inc.
  • 72. Centrosome Longitudinal section of one centriole Centrioles Microtubule 0.25 µm Microtubules Cross section of the other centriole Figure 6.22
  • 73. Cilia and Flagella • Microtubules control the beating of cilia and flagella, locomotor appendages of some cells • Cilia and flagella differ in their beating patterns © 2011 Pearson Education, Inc. Video: Chlamydomonas Video: Paramecium Cilia
  • 74. Direction of swimming (b) Motion of cilia Direction of organism’s movement Power stroke Recovery stroke (a) Motion of flagella 5 µm 15 µm Figure 6.23
  • 75. • Cilia and flagella share a common structure – A core of microtubules sheathed by the plasma membrane – A basal body that anchors the cilium or flagellum – A motor protein called dynein, which drives the bending movements of a cilium or flagellum © 2011 Pearson Education, Inc. Animation: Cilia and Flagella
  • 76. Microtubules Plasma membrane Basal body Longitudinal section of motile cilium (a) 0.5 µm 0.1 µm 0.1 µm (b) Cross section of motile cilium Outer microtubule doublet Dynein proteins Central microtubule Radial spoke Cross-linking proteins between outer doublets Plasma membrane Triplet (c) Cross section of basal body Figure 6.24
  • 78. Figure 6.24b 0.1 µm (b) Cross section of motile cilium Outer microtubule doublet Dynein proteins Central microtubule Radial spoke Cross-linking proteins between outer doublets Plasma membrane
  • 79. Figure 6.24ba 0.1 µm (b) Cross section of motile cilium Outer microtubule doublet Dynein proteins Central microtubule Radial spoke Cross-linking proteins between outer doublets
  • 80. Figure 6.24c 0.1 µm Triplet (c) Cross section of basal body
  • 81. • How dynein “walking” moves flagella and cilia − Dynein arms alternately grab, move, and release the outer microtubules – Protein cross-links limit sliding – Forces exerted by dynein arms cause doublets to curve, bending the cilium or flagellum © 2011 Pearson Education, Inc.
  • 82. Figure 6.25 Microtubule doublets Dynein protein ATP (a) Effect of unrestrained dynein movement Cross-linking proteins between outer doublets ATP Anchorage in cell (b) Effect of cross-linking proteins (c) Wavelike motion 1 2 3
  • 83. Microtubule doublets Dynein protein ATP (a) Effect of unrestrained dynein movement Figure 6.25a
  • 84. Figure 6.25b Cross-linking proteins between outer doublets ATP Anchorage in cell (b) Effect of cross-linking proteins (c) Wavelike motion 31 2
  • 85. Microfilaments (Actin Filaments) • Microfilaments are solid rods about 7 nm in diameter, built as a twisted double chain of actin subunits • The structural role of microfilaments is to bear tension, resisting pulling forces within the cell • They form a 3-D network called the cortex just inside the plasma membrane to help support the cell’s shape • Bundles of microfilaments make up the core of microvilli of intestinal cells © 2011 Pearson Education, Inc.
  • 86. Figure 6.26 Microvillus Plasma membrane Microfilaments (actin filaments) Intermediate filaments 0.25 µm
  • 87. • Microfilaments that function in cellular motility contain the protein myosin in addition to actin • In muscle cells, thousands of actin filaments are arranged parallel to one another • Thicker filaments composed of myosin interdigitate with the thinner actin fibers © 2011 Pearson Education, Inc.
  • 88. Figure 6.27 Muscle cell Actin filament Myosin Myosin filament head (a) Myosin motors in muscle cell contraction 0.5 µm 100 µm Cortex (outer cytoplasm): gel with actin network Inner cytoplasm: sol with actin subunits (b) Amoeboid movement Extending pseudopodium 30 µm (c) Cytoplasmic streaming in plant cells Chloroplast
  • 89. Figure 6.27a Muscle cell Actin filament Myosin Myosin filament (a) Myosin motors in muscle cell contraction 0.5 µm head
  • 90. Figure 6.27b 100 µm Cortex (outer cytoplasm): gel with actin network Inner cytoplasm: sol with actin subunits (b) Amoeboid movement Extending pseudopodium
  • 91. Figure 6.27c 30 µm (c) Cytoplasmic streaming in plant cells Chloroplast
  • 92. Intermediate Filaments • Intermediate filaments range in diameter from 8–12 nanometers, larger than microfilaments but smaller than microtubules • They support cell shape and fix organelles in place • Intermediate filaments are more permanent cytoskeleton fixtures than the other two classes © 2011 Pearson Education, Inc.
  • 93. Concept 6.7: Extracellular components and connections between cells help coordinate cellular activities • Most cells synthesize and secrete materials that are external to the plasma membrane • These extracellular structures include – Cell walls of plants – The extracellular matrix (ECM) of animal cells – Intercellular junctions © 2011 Pearson Education, Inc.
  • 94. Cell Walls of Plants • The cell wall is an extracellular structure that distinguishes plant cells from animal cells • Prokaryotes, fungi, and some protists also have cell walls • The cell wall protects the plant cell, maintains its shape, and prevents excessive uptake of water • Plant cell walls are made of cellulose fibers embedded in other polysaccharides and protein © 2011 Pearson Education, Inc.
  • 95. The Extracellular Matrix (ECM) of Animal Cells • Animal cells lack cell walls but are covered by an elaborate extracellular matrix (ECM) • The ECM is made up of glycoproteins such as collagen, proteoglycans, and fibronectin • ECM proteins bind to receptor proteins in the plasma membrane called integrins © 2011 Pearson Education, Inc.
  • 99. Cell Junctions • Neighboring cells in tissues, organs, or organ systems often adhere, interact, and communicate through direct physical contact • Intercellular junctions facilitate this contact • There are several types of intercellular junctions – Plasmodesmata – Tight junctions – Desmosomes – Gap junctions © 2011 Pearson Education, Inc.
  • 100. Plasmodesmata in Plant Cells • Plasmodesmata are channels that perforate plant cell walls • Through plasmodesmata, water and small solutes (and sometimes proteins and RNA) can pass from cell to cell © 2011 Pearson Education, Inc.
  • 101. Figure 6.31 Interior of cell Interior of cell 0.5 µm Plasmodesmata Plasma membranes Cell walls
  • 102. Tight Junctions, Desmosomes, and Gap Junctions in Animal Cells • At tight junctions, membranes of neighboring cells are pressed together, preventing leakage of extracellular fluid • Desmosomes (anchoring junctions) fasten cells together into strong sheets • Gap junctions (communicating junctions) provide cytoplasmic channels between adjacent cells © 2011 Pearson Education, Inc.
  • 103. Figure 6.32 Tight junctions prevent fluid from moving across a layer of cells Tight junction Tight junction TEM 0.5 µm TEM 1 µm TEM 0.1 µm Extracellular matrixPlasma membranes of adjacent cells Space between cells Ions or small molecules Desmosome Intermediate filaments Gap junction
  • 104. Tight junctions prevent fluid from moving across a layer of cells Extracellular matrix Plasma membranes of adjacent cells Space between cells Ions or small molecules Desmosome Intermediate filaments Tight junction Gap junction Figure 6.32a

Editor's Notes

  1. For the Discovery Video Cells, go to Animation and Video Files.
  2. Figure 6.2 The size range of cells.
  3. Figure 6.3 Exploring: Microscopy
  4. Figure 6.5 A prokaryotic cell.
  5. Figure 6.5 A prokaryotic cell.
  6. Figure 6.6 The plasma membrane.
  7. [
  8. Figure 6.8 Exploring: Eukaryotic Cells
  9. Figure 6.8 Exploring: Eukaryotic Cells
  10. Figure 6.9 The nucleus and its envelope.
  11. Figure 6.9 The nucleus and its envelope.
  12. Figure 6.9 The nucleus and its envelope.
  13. Figure 6.9 The nucleus and its envelope.
  14. Figure 6.9 The nucleus and its envelope.
  15. For the Cell Biology Video Staining of Endoplasmic Reticulum, go to Animation and Video Files.
  16. Figure 6.10 Ribosomes.
  17. For the Cell Biology Video ER and Mitochondria in Leaf Cells, go to Animation and Video Files.
  18. Figure 6.11 Endoplasmic reticulum (ER).
  19. Figure 6.11 Endoplasmic reticulum (ER).
  20. For the Cell Biology Video ER to Golgi Traffic, go to Animation and Video Files. For the Cell Biology Video Golgi Complex in 3D, go to Animation and Video Files. For the Cell Biology Video Secretion From the Golgi, go to Animation and Video Files.
  21. Figure 6.12 The Golgi apparatus.
  22. Figure 6.12 The Golgi apparatus.
  23. For the Cell Biology Video Phagocytosis in Action, go to Animation and Video Files.
  24. Figure 6.13 Lysosomes.
  25. Figure 6.13 Lysosomes.
  26. Figure 6.13 Lysosomes.
  27. Figure 6.14 The plant cell vacuole.
  28. Figure 6.15 Review: relationships among organelles of the endomembrane system.
  29. Figure 6.15 Review: relationships among organelles of the endomembrane system.
  30. Figure 6.15 Review: relationships among organelles of the endomembrane system.
  31. For the Cell Biology Video ER and Mitochondria in Leaf Cells, go to Animation and Video Files. For the Cell Biology Video Mitochondria in 3D, go to Animation and Video Files. For the Cell Biology Video Chloroplast Movement, go to Animation and Video Files.
  32. Figure 6.17 The mitochondrion, site of cellular respiration.
  33. Figure 6.17 The mitochondrion, site of cellular respiration.
  34. Figure 6.18 The chloroplast, site of photosynthesis.
  35. For the Cell Biology Video The Cytoskeleton in a Neuron Growth Cone, go to Animation and Video Files For the Cell Biology Video Cytoskeletal Protein Dynamics, go to Animation and Video Files.
  36. Figure 6.20 The cytoskeleton.
  37. Figure 6.21 Motor proteins and the cytoskeleton.
  38. For the Cell Biology Video Actin Network in Crawling Cells, go to Animation and Video Files. For the Cell Biology Video Actin Visualization in Dendrites, go to Animation and Video Files.
  39. Table 6.1 The Structure and Function of the Cytoskeleton
  40. Table 6.1 The Structure and Function of the Cytoskeleton
  41. Table 6.1 The Structure and Function of the Cytoskeleton
  42. For the Cell Biology Video Transport Along Microtubules, go to Animation and Video Files. For the Cell Biology Video Movement of Organelles in Vivo, go to Animation and Video Files. For the Cell Biology Video Movement of Organelles in Vitro, go to Animation and Video Files.
  43. Figure 6.22 Centrosome containing a pair of centrioles.
  44. Figure 6.23 A comparison of the beating of flagella and motile cilia.
  45. Figure 6.24 Structure of a flagellum or motile cilium.
  46. Figure 6.24 Structure of a flagellum or motile cilium.
  47. Figure 6.24 Structure of a flagellum or motile cilium.
  48. Figure 6.24 Structure of a flagellum or motile cilium.
  49. Figure 6.24 Structure of a flagellum or motile cilium.
  50. For the Cell Biology Video Motion of Isolated Flagellum, go to Animation and Video Files. For the Cell Biology Video Flagellum Movement in Swimming Sperm, go to Animation and Video Files.
  51. Figure 6.25 How dynein “walking” moves flagella and cilia.
  52. Figure 6.25 How dynein “walking” moves flagella and cilia.
  53. Figure 6.25 How dynein “walking” moves flagella and cilia.
  54. Figure 6.26 A structural role of microfilaments.
  55. Figure 6.27 Microfilaments and motility.
  56. Figure 6.27 Microfilaments and motility.
  57. Figure 6.27 Microfilaments and motility.
  58. Figure 6.27 Microfilaments and motility.
  59. For the Cell Biology Video Interphase Microtubule Dynamics, go to Animation and Video Files. For the Cell Biology Video Microtubule Sliding in Flagellum Movement, go to Animation and Video Files. For the Cell Biology Video Microtubule Dynamics, go to Animation and Video Files.
  60. For the Cell Biology Video Ciliary Motion, go to Animation and Video Files.
  61. For the Cell Biology Video Cartoon Model of a Collagen Triple Helix, go to Animation and Video Files. For the Cell Biology Video Staining of the Extracellular Matrix, go to Animation and Video Files. For the Cell Biology Video Fibronectin Fibrils, go to Animation and Video Files.
  62. Figure 6.30 Extracellular matrix (ECM) of an animal cell.
  63. Figure 6.30 Extracellular matrix (ECM) of an animal cell.
  64. Figure 6.30 Extracellular matrix (ECM) of an animal cell.
  65. Figure 6.31 Plasmodesmata between plant cells.
  66. Figure 6.32 Exploring: Cell Junctions in Animal Tissues
  67. Figure 6.32 Exploring: Cell Junctions in Animal Tissues