Ch 6: A Tour of the Cell
veneethmathew
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About This Presentation
AP Biology Powerpoint Presentations: 9th Edition
Slide Content
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
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
•The cell is the simplest collection of matter
that can be alive
•Cell structure is correlated to cellular function
•All cells are related by their descent from earlier
cells
© 2011 Pearson Education, Inc.
•All organisms are made of cells
•The cell is the simplest collection of matter
that can be alive
•Cell structure is correlated to cellular function
•All cells are related by their descent from earlier
cells
© 2011 Pearson Education, Inc.
Figure 6.1
Concept 6.1: Biologists use microscopes and
the tools of biochemistry to study cells
•Though usually too small to be seen by the
unaided eye, cells can be complex
© 2011 Pearson Education, Inc.
the tools of biochemistry to study cells
•Though usually too small to be seen by the
unaided eye, cells can be complex
© 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.
•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.
–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 mm
10 mm
1 mm
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
U
n
a
i
d
e
d
e
y
e
L
i
g
h
t
m
i
c
r
o
s
c
o
p
y
E
l
e
c
t
r
o
n
m
i
c
r
o
s
c
o
p
y
Super-
resolution
microscopy
10 m
1 m
0.1 m
1 cm
1 mm
100 mm
10 mm
1 mm
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
U
n
a
i
d
e
d
e
y
e
L
i
g
h
t
m
i
c
r
o
s
c
o
p
y
E
l
e
c
t
r
o
n
m
i
c
r
o
s
c
o
p
y
Super-
resolution
microscopy
10 m
1 m
0.1 m
1 cm
1 mm
100 mm
Human egg
Frog egg
Chicken egg
Length of some
nerve and
muscle cells
Human height
U
n
a
i
d
e
d
e
y
e
Figure 6.2a
1 m
0.1 m
1 cm
1 mm
100 mm
Human egg
Frog egg
Chicken egg
Length of some
nerve and
muscle cells
Human height
U
n
a
i
d
e
d
e
y
e
Figure 6.2a
Figure 6.2b
1 mm
100 mm
10 mm
1 mm
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
L
i
g
h
t
m
i
c
r
o
s
c
o
p
y
E
l
e
c
t
r
o
n
m
i
c
r
o
s
c
o
p
y
Super-
resolution
microscopy
1 cm
Frog egg
1 mm
100 mm
10 mm
1 mm
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
L
i
g
h
t
m
i
c
r
o
s
c
o
p
y
E
l
e
c
t
r
o
n
m
i
c
r
o
s
c
o
p
y
Super-
resolution
microscopy
1 cm
Frog egg
Brightfield
(unstained specimen)
Brightfield
(stained specimen)
5
0
m
m
Confocal
Differential-interference-
contrast (Nomarski)
Fluorescence
10 mm
Deconvolution
Super-resolution
Scanning electron
microscopy (SEM)
Transmission electron
microscopy (TEM)
Cross section
of cilium
Longitudinal section
of cilium
Cilia
Electron Microscopy (EM)
1
m
m
1
0
m
m
5
0
m
m
2 mm
2 mm
Light Microscopy (LM)
Phase-contrast
Figure 6.3
(unstained specimen)
Brightfield
(stained specimen)
5
0
m
m
Confocal
Differential-interference-
contrast (Nomarski)
Fluorescence
10 mm
Deconvolution
Super-resolution
Scanning electron
microscopy (SEM)
Transmission electron
microscopy (TEM)
Cross section
of cilium
Longitudinal section
of cilium
Cilia
Electron Microscopy (EM)
1
m
m
1
0
m
m
5
0
m
m
2 mm
2 mm
Light Microscopy (LM)
Phase-contrast
Figure 6.3
Figure 6.3a
(unstained specimen)
5
0
m
m
Brightfield
(unstained specimen)
5
0
m
m
Brightfield
Figure 6.3b
Brightfield
(stained specimen)
Brightfield
(stained specimen)
Figure 6.3c
Phase-contrast
Phase-contrast
Figure 6.3d
Differential-interference-
contrast (Nomarski)
Differential-interference-
contrast (Nomarski)
Figure 6.3e
Fluorescence
10 mm
Fluorescence
10 mm
Figure 6.3f
Confocal
5
0
m
m
Confocal
5
0
m
m
Figure 6.3fa
Confocal
5
0
m
m
Confocal
5
0
m
m
Figure 6.3fb
Confocal
5
0
m
m
Confocal
5
0
m
m
Figure 6.3g
Deconvolution
1
0
m
m
Deconvolution
1
0
m
m
Figure 6.3h
Super-resolution
1
m
m
Super-resolution
1
m
m
Figure 6.3ha
Super-resolution
1
m
m
Super-resolution
1
m
m
Figure 6.3hb
Super-resolution
1
m
m
Super-resolution
1
m
m
Figure 6.3i
Cilia
2 mm
Scanning electron
microscopy (SEM)
Cilia
2 mm
Scanning electron
microscopy (SEM)
Figure 6.3j
Longitudinal section
of cilium
Cross section
of cilium
2 mm
Transmission electron
microscopy (TEM)
Longitudinal section
of cilium
Cross section
of cilium
2 mm
Transmission electron
microscopy (TEM)
•LMs can magnify effectively to about 1,000
times the size of the actual specimen
•Various techniques enhance contrast and
enable cell components to be stained or labeled
•Most subcellular structures, including
organelles (membrane-enclosed
compartments), are too small to be resolved by
an LM
© 2011 Pearson Education, Inc.
times the size of the actual specimen
•Various techniques enhance contrast and
enable cell components to be stained or labeled
•Most subcellular structures, including
organelles (membrane-enclosed
compartments), are too small to be resolved by
an LM
© 2011 Pearson Education, Inc.
•Two basic types of electron microscopes
(EMs) are used to study subcellular structures
•Scanning electron microscopes (SEMs) focus
a beam of electrons onto the surface of a
specimen, providing images that look 3-D
•Transmission electron microscopes (TEMs)
focus a beam of electrons through a specimen
•TEMs are used mainly to study the internal
structure of cells
© 2011 Pearson Education, Inc.
(EMs) are used to study subcellular structures
•Scanning electron microscopes (SEMs) focus
a beam of electrons onto the surface of a
specimen, providing images that look 3-D
•Transmission electron microscopes (TEMs)
focus a beam of electrons through a specimen
•TEMs are used mainly to study the internal
structure of cells
© 2011 Pearson Education, Inc.
•Recent advances in light microscopy
–Confocal microscopy and deconvolution
microscopy provide sharper images of three-
dimensional tissues and cells
–New techniques for labeling cells improve
resolution
© 2011 Pearson Education, Inc.
–Confocal microscopy and deconvolution
microscopy provide sharper images of three-
dimensional tissues and cells
–New techniques for labeling cells improve
resolution
© 2011 Pearson Education, Inc.
Cell Fractionation
•Cell fractionation takes cells apart and
separates the major organelles from one
another
•Centrifuges fractionate cells into their
component parts
•Cell fractionation enables scientists to determine
the functions of organelles
•Biochemistry and cytology help correlate cell
function with structure
© 2011 Pearson Education, Inc.
•Cell fractionation takes cells apart and
separates the major organelles from one
another
•Centrifuges fractionate cells into their
component parts
•Cell fractionation enables scientists to determine
the functions of organelles
•Biochemistry and cytology help correlate cell
function with structure
© 2011 Pearson Education, Inc.
Figure 6.4
TECHNIQUE
Homogenization
Tissue
cells
Homogenate
Centrifugation
Differential
centrifugation
Centrifuged at
1,000 g
(1,000 times the
force of gravity)
for 10 min
Supernatant
poured into
next tube
20,000 g
20 min
80,000 g
60 min
Pellet rich in
nuclei and
cellular debris
150,000 g
3 hr
Pellet rich in
mitochondria
(and chloro-
plasts if cells
are from a plant)
Pellet rich in
“microsomes”
(pieces of plasma
membranes and
cells’ internal
membranes)
Pellet rich in
ribosomes
TECHNIQUE
Homogenization
Tissue
cells
Homogenate
Centrifugation
Differential
centrifugation
Centrifuged at
1,000 g
(1,000 times the
force of gravity)
for 10 min
Supernatant
poured into
next tube
20,000 g
20 min
80,000 g
60 min
Pellet rich in
nuclei and
cellular debris
150,000 g
3 hr
Pellet rich in
mitochondria
(and chloro-
plasts if cells
are from a plant)
Pellet rich in
“microsomes”
(pieces of plasma
membranes and
cells’ internal
membranes)
Pellet rich in
ribosomes
Figure 6.4a
TECHNIQUE
Homogenization
Tissue
cells
Homogenate
Centrifugation
TECHNIQUE
Homogenization
Tissue
cells
Homogenate
Centrifugation
Differential
centrifugation
Centrifuged at
1,000 g
(1,000 times the
force of gravity)
for 10 minSupernatant
poured into
next tube
20 min
60 min
Pellet rich in
nuclei and
cellular debris
3 hr
Pellet rich in
mitochondria
(and chloro-
plasts if cells
are from a plant)
Pellet rich in
“microsomes”
Pellet rich in
ribosomes
20,000 g
80,000 g
150,000 g
TECHNIQUE (cont.)
Figure 6.4b
centrifugation
Centrifuged at
1,000 g
(1,000 times the
force of gravity)
for 10 minSupernatant
poured into
next tube
20 min
60 min
Pellet rich in
nuclei and
cellular debris
3 hr
Pellet rich in
mitochondria
(and chloro-
plasts if cells
are from a plant)
Pellet rich in
“microsomes”
Pellet rich in
ribosomes
20,000 g
80,000 g
150,000 g
TECHNIQUE (cont.)
Figure 6.4b
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.
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.
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.
–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 mm
Figure 6.5
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 mm
Figure 6.5
Figure 6.5a
A thin section through the
bacterium Bacillus coagulans
(TEM)
(b)
0.5 mm
A thin section through the
bacterium Bacillus coagulans
(TEM)
(b)
0.5 mm
•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.
–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.
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 mm
(a)TEM of a plasma
membrane
Hydrophilic
region
Hydrophobic
region
Hydrophilic
region
Carbohydrate side chains
ProteinsPhospholipid
(b) Structure of the plasma membrane
Outside of cell
Inside of cell
0.1 mm
(a)TEM of a plasma
membrane
Hydrophilic
region
Hydrophobic
region
Hydrophilic
region
Carbohydrate side chains
ProteinsPhospholipid
(b) Structure of the plasma membrane
Figure 6.6a
Outside of cell
Inside of cell
0.1 mm
(a) TEM of a plasma membrane
Outside of cell
Inside of cell
0.1 mm
(a) TEM of a plasma membrane
•Metabolic requirements set upper 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 n
2
,
the volume increases by a factor of n
3
•Small cells have a greater surface area relative
to volume
© 2011 Pearson Education, Inc.
size of cells
•The surface area to volume ratio of a cell is
critical
•As the surface area increases by a factor of n
2
,
the volume increases by a factor of n
3
•Small cells have a greater surface area relative
to volume
© 2011 Pearson Education, Inc.
Surface area increases while
total volume remains constant
Total surface area
[sum of the surface areas
(height ´ width) of all box
sides ´ number of boxes]
Total volume
[height ´ width ´ length
´ number of boxes]
Surface-to-volume
(S-to-V) ratio
[surface area ¸ volume]
1
5
6 150 750
1
1251251
1.26 6
Figure 6.7
total volume remains constant
Total surface area
[sum of the surface areas
(height ´ width) of all box
sides ´ number of boxes]
Total volume
[height ´ width ´ length
´ number of boxes]
Surface-to-volume
(S-to-V) ratio
[surface area ¸ volume]
1
5
6 150 750
1
1251251
1.26 6
Figure 6.7
A Panoramic View of the Eukaryotic Cell
•A eukaryotic cell has internal membranes that
partition the cell into organelles
•Plant and animal cells have most of the same
organelles
© 2011 Pearson Education, Inc.
BioFlix: Tour of an Animal Cell
BioFlix: Tour of a Plant Cell
•A eukaryotic cell has internal membranes that
partition the cell into organelles
•Plant and animal cells have most of the same
organelles
© 2011 Pearson Education, Inc.
BioFlix: Tour of an Animal Cell
BioFlix: Tour of a Plant Cell
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
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
Figure 6.8b
Animal Cells
Cell
Nucleus
Nucleolus
Human cells from lining
of uterus (colorized TEM)
Yeast cells budding
(colorized SEM)
1
0
m
m
Fungal Cells
5
m
m
Parent
cell
Buds
1 mm
Cell wall
Vacuole
Nucleus
Mitochondrion
A single yeast cell
(colorized TEM)
Animal Cells
Cell
Nucleus
Nucleolus
Human cells from lining
of uterus (colorized TEM)
Yeast cells budding
(colorized SEM)
1
0
m
m
Fungal Cells
5
m
m
Parent
cell
Buds
1 mm
Cell wall
Vacuole
Nucleus
Mitochondrion
A single yeast cell
(colorized TEM)
Figure 6.8ba
Animal Cells
Cell
Nucleus
Nucleolus
Human cells from lining
of uterus (colorized TEM)
1
0
m
m
Animal Cells
Cell
Nucleus
Nucleolus
Human cells from lining
of uterus (colorized TEM)
1
0
m
m
Figure 6.8bb
Yeast cells budding
(colorized SEM)
Fungal Cells
5
m
m
Parent
cell
Buds
Yeast cells budding
(colorized SEM)
Fungal Cells
5
m
m
Parent
cell
Buds
Figure 6.8bc
1 mm
Cell wall
Vacuole
Nucleus
Mitochondrion
A single yeast cell
(colorized TEM)
1 mm
Cell wall
Vacuole
Nucleus
Mitochondrion
A single yeast cell
(colorized TEM)
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
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
Figure 6.8d
Plant Cells
Cells from duckweed
(colorized TEM)
Cell
5
m
m
Cell wall
Chloroplast
Nucleus
Nucleolus
8
m
m
Protistan Cells
1
m
m
Chlamydomonas
(colorized SEM)
Chlamydomonas
(colorized TEM)
Flagella
Nucleus
Nucleolus
Vacuole
Chloroplast
Cell wall
Mitochondrion
Plant Cells
Cells from duckweed
(colorized TEM)
Cell
5
m
m
Cell wall
Chloroplast
Nucleus
Nucleolus
8
m
m
Protistan Cells
1
m
m
Chlamydomonas
(colorized SEM)
Chlamydomonas
(colorized TEM)
Flagella
Nucleus
Nucleolus
Vacuole
Chloroplast
Cell wall
Mitochondrion
Figure 6.8da
Plant Cells
Cells from duckweed
(colorized TEM)
Cell
5
m
m
Cell wall
Chloroplast
Nucleus
Nucleolus
Mitochondrion
Plant Cells
Cells from duckweed
(colorized TEM)
Cell
5
m
m
Cell wall
Chloroplast
Nucleus
Nucleolus
Mitochondrion
Figure 6.8db
8
m
m
Protistan Cells
Chlamydomonas
(colorized SEM)
8
m
m
Protistan Cells
Chlamydomonas
(colorized SEM)
Figure 6.8dc
1
m
m
Chlamydomonas
(colorized TEM)
Flagella
Nucleus
Nucleolus
Vacuole
Chloroplast
Cell wall
Protistan Cells
1
m
m
Chlamydomonas
(colorized TEM)
Flagella
Nucleus
Nucleolus
Vacuole
Chloroplast
Cell wall
Protistan Cells
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.
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.
•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
.
2
5
m
m
1
m
m
Nuclear lamina (TEM)
Chromatin
1 mm
Figure 6.9
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
.
2
5
m
m
1
m
m
Nuclear lamina (TEM)
Chromatin
1 mm
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
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 mm
Nuclear envelope:
Inner membrane
Outer membrane
Nuclear pore
Surface of nuclear
envelope
1 mm
Figure 6.9c
Pore complexes (TEM)
0
.
2
5
m
m
Pore complexes (TEM)
0
.
2
5
m
m
Figure 6.9d
1
m
m
Nuclear lamina (TEM)
1
m
m
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.
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.
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.
•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 mm
Free ribosomes in cytosol
Endoplasmic reticulum (ER)
Ribosomes bound to ER
Large
subunit
Small
subunit
Diagram of a ribosome
TEM showing ER and
ribosomes
0.25 mm
Free ribosomes in cytosol
Endoplasmic reticulum (ER)
Ribosomes bound to ER
Large
subunit
Small
subunit
Diagram of a ribosome
TEM showing ER and
ribosomes
Figure 6.10a
0.25 mm
Free ribosomes in cytosol
Endoplasmic reticulum (ER)
Ribosomes bound to ER
TEM showing ER and
ribosomes
0.25 mm
Free ribosomes in cytosol
Endoplasmic reticulum (ER)
Ribosomes bound to ER
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.
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.
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
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
Smooth ER
Rough ER
Cisternae
Ribosomes
Transport vesicle
Transitional ER
Nuclear
envelope
ER lumen
Figure 6.11b
Smooth ER Rough ER
200 nm
Smooth ER Rough ER
200 nm
Functions of Smooth ER
•The smooth ER
–Synthesizes lipids
–Metabolizes carbohydrates
–Detoxifies drugs and poisons
–Stores calcium ions
© 2011 Pearson Education, Inc.
•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 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.
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 mm
TEM of Golgi apparatus
Cisternae
cis face
(“receiving” side of
Golgi apparatus)
trans face
(“shipping” side of
Golgi apparatus)
0.1 mm
TEM of Golgi apparatus
Cisternae
Figure 6.12a
TEM of Golgi apparatus
0.1 mm
TEM of Golgi apparatus
0.1 mm
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
•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.
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 mm
Digestive
enzymes
Digestion
Food vacuole
Lysosome
Plasma membrane
(a) Phagocytosis
Vesicle containing
two damaged
organelles
1 mm
Mitochondrion
fragment
Peroxisome
fragment
(b) Autophagy
Peroxisome
Vesicle
Mitochondrion
Lysosome
Digestion
Nucleus
Lysosome
1 mm
Digestive
enzymes
Digestion
Food vacuole
Lysosome
Plasma membrane
(a) Phagocytosis
Vesicle containing
two damaged
organelles
1 mm
Mitochondrion
fragment
Peroxisome
fragment
(b) Autophagy
Peroxisome
Vesicle
Mitochondrion
Lysosome
Digestion
Figure 6.13a
Nucleus
Lysosome
1 mm
Digestive
enzymes
Digestion
Food vacuole
Lysosome
Plasma membrane
(a) Phagocytosis
Nucleus
Lysosome
1 mm
Digestive
enzymes
Digestion
Food vacuole
Lysosome
Plasma membrane
(a) Phagocytosis
Figure 6.13aa
Nucleus
Lysosome
1 mm
Nucleus
Lysosome
1 mm
Figure 6.13b
Vesicle containing
two damaged
organelles
1 mm
Mitochondrion
fragment
Peroxisome
fragment
Peroxisome
Vesicle
Mitochondrion
Lysosome
Digestion
(b) Autophagy
Vesicle containing
two damaged
organelles
1 mm
Mitochondrion
fragment
Peroxisome
fragment
Peroxisome
Vesicle
Mitochondrion
Lysosome
Digestion
(b) Autophagy
Figure 6.13bb
Vesicle containing
two damaged
organelles
1 mm
Mitochondrion
fragment
Peroxisome
fragment
Vesicle containing
two damaged
organelles
1 mm
Mitochondrion
fragment
Peroxisome
fragment
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.
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
•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 mm
Central vacuole
Cytosol
Nucleus
Cell wall
Chloroplast
Central
vacuole
5 mm
Figure 6.14a
Cytosol
Nucleus
Cell wall
Chloroplast
Central
vacuole
5 mm
Cytosol
Nucleus
Cell wall
Chloroplast
Central
vacuole
5 mm
The Endomembrane System: A Review
•The endomembrane system is a complex and
dynamic player in the cell’s compartmental
organization
© 2011 Pearson Education, Inc.
•The endomembrane system is a complex and
dynamic player in the cell’s compartmental
organization
© 2011 Pearson Education, Inc.
Figure 6.15-1
Smooth ER
Nucleus
Rough ER
Plasma
membrane
Smooth ER
Nucleus
Rough ER
Plasma
membrane
Figure 6.15-2
Smooth ER
Nucleus
Rough ER
Plasma
membrane
cis Golgi
trans Golgi
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
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.
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
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
•The Endosymbiont theory
–An early ancestor of eukaryotic cells engulfed
a nonphotosynthetic prokaryotic cell, which
formed an endosymbiont relationship with its
host
–The host cell and endosymbiont merged into
a single organism, a eukaryotic cell with a
mitochondrion
–At least one of these cells may have taken up
a photosynthetic prokaryote, becoming the
ancestor of cells that contain chloroplasts
© 2011 Pearson Education, Inc.
–An early ancestor of eukaryotic cells engulfed
a nonphotosynthetic prokaryotic cell, which
formed an endosymbiont relationship with its
host
–The host cell and endosymbiont merged into
a single organism, a eukaryotic cell with a
mitochondrion
–At least one of these cells may have taken up
a photosynthetic prokaryote, becoming the
ancestor of cells that contain chloroplasts
© 2011 Pearson Education, Inc.
Figure 6.16
NucleusEndoplasmic
reticulum
Nuclear
envelope
Ancestor of
eukaryotic cells
(host cell)
Engulfing of oxygen-
using nonphotosynthetic
prokaryote, which
becomes a mitochondrion
Mitochondrion
Nonphotosynthetic
eukaryote
Mitochondrion
At least
one cell
Photosynthetic eukaryote
Engulfing of
photosynthetic
prokaryote
Chloroplast
NucleusEndoplasmic
reticulum
Nuclear
envelope
Ancestor of
eukaryotic cells
(host cell)
Engulfing of oxygen-
using nonphotosynthetic
prokaryote, which
becomes a mitochondrion
Mitochondrion
Nonphotosynthetic
eukaryote
Mitochondrion
At least
one cell
Photosynthetic eukaryote
Engulfing of
photosynthetic
prokaryote
Chloroplast
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.
•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 mm
Mitochondrial
DNA
Nuclear DNA
Mitochondria
10 mm
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 mm
Mitochondrial
DNA
Nuclear DNA
Mitochondria
10 mm
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 mm
membrane
Intermembrane space
Outer
DNA
Inner
membrane
Cristae
Matrix
Free
ribosomes
in the
mitochondrial
matrix
(a) Diagram and TEM of mitochondrion
0.1 mm
membrane
Figure 6.17aa
Outer
membrane
Inner
membrane
Cristae
Matrix
0.1 mm
Outer
membrane
Inner
membrane
Cristae
Matrix
0.1 mm
Figure 6.17b
(b)Network of mitochondria in a protist
cell (LM)
Mitochondrial
DNA
Nuclear DNA
Mitochondria
10 mm
(b)Network of mitochondria in a protist
cell (LM)
Mitochondrial
DNA
Nuclear DNA
Mitochondria
10 mm
Chloroplasts: Capture of Light Energy
•Chloroplasts contain the green pigment
chlorophyll, as well as enzymes and other
molecules that function in photosynthesis
•Chloroplasts are found in leaves and other
green organs of plants and in algae
© 2011 Pearson Education, Inc.
•Chloroplasts contain the green pigment
chlorophyll, as well as enzymes and other
molecules that function in photosynthesis
•Chloroplasts are found in leaves and other
green organs of plants and in algae
© 2011 Pearson Education, Inc.
•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.
–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 mmIntermembrane spaceThylakoid
(a) Diagram and TEM of chloroplast (b) Chloroplasts in an algal cell
Chloroplasts
(red)
50 mm
DNA
Ribosomes
Stroma
Inner and outer
membranes
Granum
1 mmIntermembrane spaceThylakoid
(a) Diagram and TEM of chloroplast (b) Chloroplasts in an algal cell
Chloroplasts
(red)
50 mm
DNA
Figure 6.18a
Ribosomes
Stroma
Inner and outer
membranes
Granum
1 mm
Intermembrane spaceThylakoid
(a) Diagram and TEM of chloroplast
DNA
Ribosomes
Stroma
Inner and outer
membranes
Granum
1 mm
Intermembrane spaceThylakoid
(a) Diagram and TEM of chloroplast
DNA
Figure 6.18aa
Stroma
Inner and outer
membranes
Granum
1 mm
Stroma
Inner and outer
membranes
Granum
1 mm
Figure 6.18b
(b) Chloroplasts in an algal cell
Chloroplasts
(red)
50 mm
(b) Chloroplasts in an algal cell
Chloroplasts
(red)
50 mm
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.
•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.
Figure 6.19
Chloroplast
Peroxisome
Mitochondrion
1 mm
Chloroplast
Peroxisome
Mitochondrion
1 mm
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.
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
1
0
m
m
1
0
m
m
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.
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 mm VesiclesMicrotubule
(b)
ATP
Vesicle
(a)
Motor protein
(ATP powered)
Microtubule
of cytoskeleton
Receptor for
motor protein
0.25 mm VesiclesMicrotubule
(b)
Figure 6.21a
0.25 mm VesiclesMicrotubule
(b)
0.25 mm VesiclesMicrotubule
(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.
•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.
Column of tubulin dimers
Tubulin dimer
25 nm
a b
Actin subunit
7 nm
Keratin proteins
8-12 nm
Fibrous subunit (keratins
coiled together)
10 mm 10 mm 5 mm
Table 6.1
Tubulin dimer
25 nm
a b
Actin subunit
7 nm
Keratin proteins
8-12 nm
Fibrous subunit (keratins
coiled together)
10 mm 10 mm 5 mm
Table 6.1
Tubulin dimer
25 nm
a b
Column of tubulin dimers
10 mm
Table 6.1a
25 nm
a b
Column of tubulin dimers
10 mm
Table 6.1a
Table 6.1aa
10 mm
10 mm
10 mm
Actin subunit
7 nm
Table 6.1b
Actin subunit
7 nm
Table 6.1b
Table 6.1bb
10 mm
10 mm
5 mm
Keratin proteins
Fibrous subunit (keratins
coiled together)
8-12 nm
Table 6.1c
Keratin proteins
Fibrous subunit (keratins
coiled together)
8-12 nm
Table 6.1c
Table 6.1cc
5 mm
5 mm
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.
•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.
•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 mm
Microtubules Cross section
of the other centriole
Figure 6.22
Longitudinal
section of
one centriole
Centrioles
Microtubule
0.25 mm
Microtubules Cross section
of the other centriole
Figure 6.22
Figure 6.22a
Longitudinal
section of
one centriole
0.25 mm
Microtubules Cross section
of the other centriole
Longitudinal
section of
one centriole
0.25 mm
Microtubules Cross section
of the other centriole
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
•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 mm
15 mm
Figure 6.23
(b) Motion of cilia
Direction of organism’s movement
Power stroke Recovery stroke
(a) Motion of flagella
5 mm
15 mm
Figure 6.23
Figure 6.23a
5 mm
5 mm
Figure 6.23b
15 mm
15 mm
•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
–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 mm
0.1 mm
0.1 mm
(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
Plasma
membrane
Basal body
Longitudinal section
of motile cilium
(a)
0.5 mm
0.1 mm
0.1 mm
(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 mm
(a)
Microtubules
Plasma
membrane
Basal body
Longitudinal section
of motile cilium
0.5 mm
(a)
Figure 6.24b
0.1 mm
(b)Cross section of
motile cilium
Outer microtubule
doublet
Dynein proteins
Central
microtubule
Radial
spoke
Cross-linking
proteins between
outer doublets
Plasma membrane
0.1 mm
(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 mm
(b)Cross section of
motile cilium
Outer microtubule
doublet
Dynein proteins
Central
microtubule
Radial
spoke
Cross-linking
proteins between
outer doublets
0.1 mm
(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 mm
Triplet
(c)Cross section of
basal body
0.1 mm
Triplet
(c)Cross section of
basal body
Figure 6.24ca
0.1 mm
Triplet
(c)Cross section of
basal body
0.1 mm
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.
−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
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
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
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.
•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 mm
Microvillus
Plasma membrane
Microfilaments (actin
filaments)
Intermediate filaments
0.25 mm
•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.
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 mm
100 mm
Cortex (outer cytoplasm):
gel with actin network
Inner cytoplasm: sol
with actin subunits
(b) Amoeboid movement
Extending
pseudopodium
30 mm
(c) Cytoplasmic streaming in plant cells
Chloroplast
Muscle cell
Actin
filament
Myosin
Myosin
filament
head
(a) Myosin motors in muscle cell contraction
0.5 mm
100 mm
Cortex (outer cytoplasm):
gel with actin network
Inner cytoplasm: sol
with actin subunits
(b) Amoeboid movement
Extending
pseudopodium
30 mm
(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 mm
head
Muscle cell
Actin
filament
Myosin
Myosin
filament
(a) Myosin motors in muscle cell contraction
0.5 mm
head
Figure 6.27aa
0.5 mm
0.5 mm
Figure 6.27b
100 mm
Cortex (outer cytoplasm):
gel with actin network
Inner cytoplasm: sol
with actin subunits
(b) Amoeboid movement
Extending
pseudopodium
100 mm
Cortex (outer cytoplasm):
gel with actin network
Inner cytoplasm: sol
with actin subunits
(b) Amoeboid movement
Extending
pseudopodium
Figure 6.27c
30 mm
(c) Cytoplasmic streaming in plant cells
Chloroplast
30 mm
(c) Cytoplasmic streaming in plant cells
Chloroplast
•Localized contraction brought about by actin and
myosin also drives amoeboid movement
•Pseudopodia (cellular extensions) extend and
contract through the reversible assembly and
contraction of actin subunits into microfilaments
© 2011 Pearson Education, Inc.
myosin also drives amoeboid movement
•Pseudopodia (cellular extensions) extend and
contract through the reversible assembly and
contraction of actin subunits into microfilaments
© 2011 Pearson Education, Inc.
•Cytoplasmic streaming is a circular flow of
cytoplasm within cells
•This streaming speeds distribution of materials
within the cell
•In plant cells, actin-myosin interactions and sol-
gel transformations drive cytoplasmic streaming
© 2011 Pearson Education, Inc.
Video: Cytoplasmic Streaming
cytoplasm within cells
•This streaming speeds distribution of materials
within the cell
•In plant cells, actin-myosin interactions and sol-
gel transformations drive cytoplasmic streaming
© 2011 Pearson Education, Inc.
Video: Cytoplasmic Streaming
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.
•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.
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 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.
•Plant cell walls may have multiple layers
–Primary cell wall: relatively thin and flexible
–Middle lamella: thin layer between primary walls
of adjacent cells
–Secondary cell wall (in some cells): added
between the plasma membrane and the primary
cell wall
•Plasmodesmata are channels between adjacent
plant cells
© 2011 Pearson Education, Inc.
–Primary cell wall: relatively thin and flexible
–Middle lamella: thin layer between primary walls
of adjacent cells
–Secondary cell wall (in some cells): added
between the plasma membrane and the primary
cell wall
•Plasmodesmata are channels between adjacent
plant cells
© 2011 Pearson Education, Inc.
Secondary
cell wall
Primary
cell wall
Middle
lamella
Central vacuole
Cytosol
Plasma membrane
Plant cell walls
Plasmodesmata
1 mm
Figure 6.28
cell wall
Primary
cell wall
Middle
lamella
Central vacuole
Cytosol
Plasma membrane
Plant cell walls
Plasmodesmata
1 mm
Figure 6.28
Figure 6.28a
Secondary
cell wall
Primary
cell wall
Middle
lamella
1 mm
Secondary
cell wall
Primary
cell wall
Middle
lamella
1 mm
Figure 6.29
RESULTS 10 mm
Distribution of cellulose
synthase over time
Distribution of
microtubules
over time
RESULTS 10 mm
Distribution of cellulose
synthase over time
Distribution of
microtubules
over time
Figure 6.29a
10 mm
Distribution of cellulose
synthase over time
10 mm
Distribution of cellulose
synthase over time
Figure 6.29b
10 mm
Distribution of
microtubules
over time
10 mm
Distribution of
microtubules
over time
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.
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
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 FLUID
Collagen
Fibronectin
Plasma
membrane
Micro-
filaments
CYTOPLASM
Integrins
Proteoglycan
complex
EXTRACELLULAR FLUID
Collagen
Fibronectin
Plasma
membrane
Micro-
filaments
CYTOPLASM
Integrins
Proteoglycan
complex
Figure 6.30b
Polysaccharide
molecule
Carbohydrates
Core
protein
Proteoglycan
molecule
Proteoglycan complex
Polysaccharide
molecule
Carbohydrates
Core
protein
Proteoglycan
molecule
Proteoglycan complex
•Functions of the ECM
–Support
–Adhesion
–Movement
–Regulation
© 2011 Pearson Education, Inc.
–Support
–Adhesion
–Movement
–Regulation
© 2011 Pearson Education, Inc.
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.
•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.
•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 mm
Plasmodesmata Plasma membranes
Cell walls
Interior
of cell
Interior
of cell
0.5 mm
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.
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.
© 2011 Pearson Education, Inc.
Animation: Tight Junctions
Animation: Desmosomes
Animation: Gap Junctions
Animation: Tight Junctions
Animation: Desmosomes
Animation: Gap Junctions
Figure 6.32
Tight junctions prevent
fluid from moving
across a layer of cells
Tight junction
Tight junction
TEM
0.5 mm
TEM
1 mm
T
E
M
0.1 mm
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
Tight junction
Tight junction
TEM
0.5 mm
TEM
1 mm
T
E
M
0.1 mm
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
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
Figure 6.32b
Tight junction
TEM
0.5 mm
Tight junction
TEM
0.5 mm
Figure 6.32c
TEM
1 mm
TEM
1 mm
Figure 6.32d
T
E
M
0.1 mm
T
E
M
0.1 mm
The Cell: A Living Unit Greater Than the
Sum of Its Parts
•Cells rely on the integration of structures and
organelles in order to function
•For example, a macrophage’s ability to destroy
bacteria involves the whole cell, coordinating
components such as the cytoskeleton,
lysosomes, and plasma membrane
© 2011 Pearson Education, Inc.
Sum of Its Parts
•Cells rely on the integration of structures and
organelles in order to function
•For example, a macrophage’s ability to destroy
bacteria involves the whole cell, coordinating
components such as the cytoskeleton,
lysosomes, and plasma membrane
© 2011 Pearson Education, Inc.
Figure 6.33
5
m
m
5
m
m
Figure 6.UN01
Nucleus
(ER)
(Nuclear
envelope)
Nucleus
(ER)
(Nuclear
envelope)
Figure 6.UN01a
Nucleus
(ER)
Nucleus
(ER)
Figure 6.UN01b
(Nuclear
envelope)
(Nuclear
envelope)
Figure 6.UN01c
Figure 6.UN02
Figure 6.UN03
Figure 6.UN04
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