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CAMPBELL BIOLOGY IN FOCUS
© 2014 Pearson Education, Inc.
Urry • Cain • Wasserman • Minorsky • Jackson • Reece
Lecture Pres...
Overview: The Fundamental Units of Life
 All organisms are made of cells
 The cell is the simplest collection of matter
...
© 2014 Pearson Education, Inc.
Figure 4.1
Concept 4.1: Biologists use microscopes and the
tools of biochemistry to study cells
 Most cells are between 1 and 100 µm...
Microscopy
 Scientists use microscopes to visualize cells too
small to see with the naked eye
 In a light microscope (LM...
 Three important parameters of microscopy
 Magnification, the ratio of an object’s image
size to its real size
 Resolut...
© 2014 Pearson Education, Inc.
Figure 4.2
Most plant and
animal cells
Length of some
nerve and
muscle cells
Viruses
Smalle...
© 2014 Pearson Education, Inc.
Figure 4.2a
Length of some
nerve and
muscle cells
Human height
Chicken egg
Frog egg
Human e...
© 2014 Pearson Education, Inc.
Figure 4.2b
Most plant and
animal cells
Viruses
Smallest bacteria
Nucleus
Most bacteria
Mit...
 LMs can magnify effectively to about 1,000 times the
size of the actual specimen
 Various techniques enhance contrast a...
 Two basic types of electron microscopes (EMs) are
used to study subcellular structures
 Scanning electron microscopes (...
© 2014 Pearson Education, Inc.
Figure 4.3
Scanning electron
microscopy (SEM)
Transmission electron
microscopy (TEM)
Longit...
© 2014 Pearson Education, Inc.
Figure 4.3a
50µm
Brightfield
(unstained specimen)
Brightfield
(stained specimen)
Differenti...
© 2014 Pearson Education, Inc.
Figure 4.3aa
50µm
Brightfield
(unstained specimen)
© 2014 Pearson Education, Inc.
Figure 4.3ab
Brightfield
(stained specimen)
50µm
© 2014 Pearson Education, Inc.
Figure 4.3ac
Phase-contrast
50µm
© 2014 Pearson Education, Inc.
Figure 4.3ad
Differential-interference
contrast (Nomarski)
50µm
© 2014 Pearson Education, Inc.
Figure 4.3b
50µm
10µm
Fluorescence Confocal
Light Microscopy (LM)
© 2014 Pearson Education, Inc.
Figure 4.3ba
10µm
Fluorescence
© 2014 Pearson Education, Inc.
Figure 4.3bb
Confocal: without technique
50µm
© 2014 Pearson Education, Inc.
Figure 4.3bc
Confocal: with technique
50µm
© 2014 Pearson Education, Inc.
Figure 4.3c
Scanning electron
microscopy (SEM)
Transmission electron
microscopy (TEM)
Longi...
© 2014 Pearson Education, Inc.
Figure 4.3ca
Scanning electron
microscopy (SEM)
Cilia
2 µm
© 2014 Pearson Education, Inc.
Figure 4.3cb
Transmission electron
microscopy (TEM)
Longitudinal section
of cilium
Cross se...
 Recent advances in light microscopy
 Labeling molecules or structures with fluorescent
markers improves visualization o...
Cell Fractionation
 Cell fractionation breaks up cells and separates the
components, using centrifugation
 Cell componen...
Concept 4.2: Eukaryotic cells have internal
membranes that compartmentalize their functions
 The basic structural and fun...
Comparing Prokaryotic and Eukaryotic Cells
 Basic features of all cells
 Plasma membrane
 Semifluid substance called cy...
 Prokaryotic cells are characterized by having
 No nucleus
 DNA in an unbound region called the nucleoid
 No membrane-...
© 2014 Pearson Education, Inc.
Figure 4.4
(a) A typical rod-shaped
bacterium
0.5 µm
(b) A thin section through
the bacteri...
© 2014 Pearson Education, Inc.
Figure 4.4a
0.5 µm
(b) A thin section through
the bacterium Bacillus
coagulans (TEM)
Nucleo...
 Eukaryotic cells are characterized by having
 DNA in a nucleus that is bounded by a membranous
nuclear envelope
 Membr...
 The plasma membrane is a selective barrier that
allows sufficient passage of oxygen, nutrients, and
waste to service the...
© 2014 Pearson Education, Inc.
Figure 4.5
0.1 µm
(a) TEM of a plasma
membraneOutside of cell
(b) Structure of the plasma m...
© 2014 Pearson Education, Inc.
Figure 4.5a
0.1 µm
(a) TEM of a plasma
membrane
Outside of cell
Inside
of cell
© 2014 Pearson Education, Inc.
Figure 4.5b
(b) Structure of the plasma membrane
Hydrophilic
region
Hydrophilic
region
Hydr...
 Metabolic requirements set upper limits on the size
of cells
 The ratio of surface area to volume of a cell is critical...
© 2014 Pearson Education, Inc.
Figure 4.6
750
Surface area increases while
total volume remains constant
125
150
125
6
1
6...
A Panoramic View of the Eukaryotic Cell
 A eukaryotic cell has internal membranes that
divide the cell into compartments—...
© 2014 Pearson Education, Inc.
Figure 4.7a
CYTOSKELETON:
NUCLEUS
ENDOPLASMIC RETICULUM (ER)
Smooth ER
Rough ERFlagellum
Ce...
© 2014 Pearson Education, Inc.
Figure 4.7b
CYTO-
SKELETON
NUCLEUS
Smooth endoplasmic
reticulum
Chloroplast
Central vacuole...
© 2014 Pearson Education, Inc.
Figure 4.7c
Nucleolus
Nucleus
Cell
10µm
Human cells from lining of uterus
(colorized TEM)
© 2014 Pearson Education, Inc.
Figure 4.7d
5µm
Parent
cell
Buds
Yeast cells budding (colorized SEM)
© 2014 Pearson Education, Inc.
Figure 4.7e
1 µm
A single yeast cell (colorized TEM)
Mitochondrion
Nucleus
Vacuole
Cell wall
© 2014 Pearson Education, Inc.
Figure 4.7f
5µm
Cell wall
Cell
Chloroplast
Mitochondrion
Nucleus
Nucleolus
Cells from duckw...
© 2014 Pearson Education, Inc.
Figure 4.7g
8µm
Chlamydomonas
(colorized SEM)
© 2014 Pearson Education, Inc.
Figure 4.7h
1µm
Chlamydomonas (colorized TEM)
Cell wall
Flagella
Chloroplast
Vacuole
Nucleu...
Concept 4.3: The eukaryotic cell’s genetic
instructions are housed in the nucleus and carried
out by the ribosomes
 The n...
The Nucleus: Information Central
 The nucleus contains most of the cell’s genes and
is usually the most conspicuous organ...
 Pores regulate the entry and exit of molecules from
the nucleus
 The shape of the nucleus is maintained by the
nuclear ...
© 2014 Pearson Education, Inc.
Figure 4.8
Ribosome
1 µm
Chromatin
Rough ER
Nucleus
Nucleolus
Nucleus
Chromatin
0.5µm
0.25µ...
© 2014 Pearson Education, Inc.
Figure 4.8a
Ribosome
Chromatin
Rough ER
Nucleus
Nucleolus
Chromatin
Nuclear envelope:
Nucle...
© 2014 Pearson Education, Inc.
Figure 4.8b
1 µm
Nuclear envelope:
Nuclear pore
Inner membrane
Outer membrane
Surface of nu...
© 2014 Pearson Education, Inc.
Figure 4.8c
0.25µm
Pore complexes (TEM)
© 2014 Pearson Education, Inc.
Figure 4.8d
0.5µm
Nuclear lamina (TEM)
 In the nucleus, DNA is organized into discrete units
called chromosomes
 Each chromosome is one long DNA molecule
assoc...
Ribosomes: Protein Factories
 Ribosomes are complexes of ribosomal RNA and
protein
 Ribosomes carry out protein synthesi...
© 2014 Pearson Education, Inc.
Figure 4.9
TEM showing ER and ribosomes Diagram of a ribosome
Ribosomes bound to ER
Free ri...
© 2014 Pearson Education, Inc.
Figure 4.9a
TEM showing ER and ribosomes
Ribosomes bound to ER
Free ribosomes in cytosol
En...
Concept 4.4: The endomembrane system
regulates protein traffic and performs metabolic
functions in the cell
 Components o...
The Endoplasmic Reticulum: Biosynthetic Factory
 The endoplasmic reticulum (ER) accounts for
more than half of the total ...
© 2014 Pearson Education, Inc.
Figure 4.10
Transport vesicle
Smooth ER
Rough
ER
Ribosomes Transitional
ER
Cisternae
ER lum...
© 2014 Pearson Education, Inc.
Figure 4.10a
Transport vesicle
Smooth ER
Rough
ER
Ribosomes Transitional
ER
Cisternae
ER lu...
© 2014 Pearson Education, Inc.
Figure 4.10b
Smooth ER Rough ER
0.2 µm
Functions of Smooth ER
 The smooth ER
 Synthesizes lipids
 Metabolizes carbohydrates
 Detoxifies drugs and poisons
 S...
Functions of Rough ER
 The rough ER
 Has bound ribosomes, which secrete glycoproteins
(proteins covalently bonded to car...
 The Golgi apparatus consists of flattened
membranous sacs called cisternae
 Functions of the Golgi apparatus
 Modifies...
© 2014 Pearson Education, Inc.
Figure 4.11
TEM of Golgi apparatus
Golgi
apparatus
trans face
(“shipping”
side of Golgi
app...
© 2014 Pearson Education, Inc.
Figure 4.11a
trans face
(“shipping”
side of Golgi
apparatus)
Cisternae
cis face
(“receiving...
© 2014 Pearson Education, Inc.
Figure 4.11b
TEM of Golgi apparatus
0.1 µm
Lysosomes: Digestive Compartments
 A lysosome is a membranous sac of hydrolytic
enzymes that can digest macromolecules
 ...
Animation: Lysosome Formation
Video: Phagocytosis
 Some types of cell can engulf another cell by
phagocytosis; this forms...
© 2014 Pearson Education, Inc.
Figure 4.12
Lysosome
1 µmNucleus
Lysosome
Digestive
enzymes
Plasma
membrane
Food vacuole
Ly...
© 2014 Pearson Education, Inc.
Figure 4.12a
Lysosome
Digestive
enzymes
Plasma
membrane
Food vacuole
Lysosomes: Phagocytosi...
© 2014 Pearson Education, Inc.
Figure 4.12b
Lysosome
1 µmNucleus
© 2014 Pearson Education, Inc.
Figure 4.13
Lysosome
Lysosomes: Autophagy
Peroxisome
Mitochondrion
Vesicle
Digestion
Mitoch...
© 2014 Pearson Education, Inc.
Figure 4.13a
Lysosome
Lysosomes: Autophagy
Peroxisome
Mitochondrion
Vesicle
Digestion
© 2014 Pearson Education, Inc.
Figure 4.13b
Mitochondrion
fragment
Peroxisome
fragment
Vesicle containing two
damaged orga...
Vacuoles: Diverse Maintenance Compartments
 Vacuoles are large vesicles derived from the
endoplasmic reticulum and Golgi ...
 Food vacuoles are formed by phagocytosis
 Contractile vacuoles, found in many freshwater
protists, pump excess water ou...
© 2014 Pearson Education, Inc.
Figure 4.14
Central vacuole
Central
vacuole
Chloroplast
Cytosol
Cell wall
Nucleus
Plant cel...
© 2014 Pearson Education, Inc.
Figure 4.14a
Central
vacuole
Chloroplast
Cytosol
Cell wall
Nucleus
Plant cell vacuole 5 µm
The Endomembrane System: A Review
 The endomembrane system is a complex and
dynamic player in the cell’s compartmental
or...
© 2014 Pearson Education, Inc.
Figure 4.15-1
Rough ER
Nucleus
Smooth ER
Plasma
membrane
© 2014 Pearson Education, Inc.
Figure 4.15-2
Plasma
membrane
Rough ER
cis Golgi
Nucleus
Smooth ER
trans Golgi
© 2014 Pearson Education, Inc.
Figure 4.15-3
Plasma
membrane
Rough ER
cis Golgi
Nucleus
Smooth ER
trans Golgi
Concept 4.5: Mitochondria and chloroplasts
change energy from one form to another
 Mitochondria are the sites of cellular...
 Mitochondria and chloroplasts have similarities
with bacteria
 Enveloped by a double membrane
 Contain free ribosomes ...
 The endosymbiont theory
 An early ancestor of eukaryotic cells engulfed a
nonphotosynthetic prokaryotic cell, which for...
© 2014 Pearson Education, Inc.
Figure 4.16
Mitochondrion
Mitochondrion
Nonphotosynthetic
eukaryote
Photosynthetic eukaryot...
Mitochondria: Chemical Energy Conversion
 Mitochondria are in nearly all eukaryotic cells
 They have a smooth outer memb...
© 2014 Pearson Education, Inc.
Figure 4.17
Free
ribosomes
in the
mitochondrial
matrix
Mitochondrion
Intermembrane space
Ma...
© 2014 Pearson Education, Inc.
Figure 4.17a
Matrix
Cristae
Outer
membrane
Inner
membrane
0.1 µm
Chloroplasts: Capture of Light Energy
 Chloroplasts contain the green pigment chlorophyll,
as well as enzymes and other m...
 Chloroplast structure includes
 Thylakoids, membranous sacs, stacked to form
a granum
 Stroma, the internal fluid
 Th...
© 2014 Pearson Education, Inc.
Figure 4.18
Intermembrane space
Ribosomes
Inner and outer
membranes
1 µm
Stroma
Granum
DNA
...
© 2014 Pearson Education, Inc.
Figure 4.18a
Intermembrane space
Ribosomes
Inner and outer
membranes
1 µm
Stroma
Granum
DNA...
© 2014 Pearson Education, Inc.
Figure 4.18aa
Inner and outer
membranes
1 µm
Stroma
Granum
© 2014 Pearson Education, Inc.
Figure 4.18b
50 µm
(b) Chloroplasts in an algal cell
Chloroplasts
(red)
Peroxisomes: Oxidation
 Peroxisomes are specialized metabolic
compartments bounded by a single membrane
 Peroxisomes pro...
© 2014 Pearson Education, Inc.
Figure 4.19
Chloroplast
1 µm
Peroxisome
Mitochondrion
Concept 4.6: The cytoskeleton is a network of
fibers that organizes structures and activities in
the cell
 The cytoskelet...
© 2014 Pearson Education, Inc.
Figure 4.20
10µm
Roles of the Cytoskeleton: Support and Motility
 The cytoskeleton helps to support the cell and
maintain its shape
 It i...
© 2014 Pearson Education, Inc.
Figure 4.21
Microtubule Vesicles
(b) SEM of a squid giant axon
Receptor for
motor protein
0...
© 2014 Pearson Education, Inc.
Figure 4.21a
Microtubule Vesicles
(b) SEM of a squid giant axon
0.25 µm
Components of the Cytoskeleton
 Three main types of fibers make up the cytoskeleton
 Microtubules are the thickest of th...
© 2014 Pearson Education, Inc.
Video: Actin in Crawling Cell
Video: Actin in Neuron
Video: Actin Cytoskeleton
Video: Cytop...
© 2014 Pearson Education, Inc.
Table 4.1
© 2014 Pearson Education, Inc.
Table 4.1a
Column of tubulin dimers
Microtubules
25 nm
Tubulin dimerβα
© 2014 Pearson Education, Inc.
Table 4.1b
Actin subunit
Microfilaments
7 nm
© 2014 Pearson Education, Inc.
Table 4.1c
Keratin
proteins
Fibrous subunit
(keratins coiled
together)
Intermediate filamen...
Microtubules
 Microtubules are hollow rods constructed from
globular protein dimers called tubulin
 Functions of microtu...
Centrosomes and Centrioles
 In animal cells, microtubules grow out from a
centrosome near the nucleus
 The centrosome is...
© 2014 Pearson Education, Inc.
Animation: Cilia Flagella
Video: Ciliary Motion
Video: Chlamydomonas
Video: Flagellum Micro...
© 2014 Pearson Education, Inc.
Figure 4.22
Microtubule
Centrioles
Centrosome
Cilia and Flagella
 Microtubules control the beating of cilia and
flagella, microtubule-containing extensions
projecting ...
 Cilia and flagella share a common structure
 A core of microtubules sheathed by the plasma
membrane
 A basal body that...
© 2014 Pearson Education, Inc.
Figure 4.23
Plasma
membrane
Microtubules
Basal body
(a) Longitudinal section
of motile cili...
© 2014 Pearson Education, Inc.
Figure 4.23a
Plasma
membrane
Microtubules
Basal body
(a) Longitudinal section of
motile cil...
© 2014 Pearson Education, Inc.
Figure 4.23b
(b) Cross section of
motile cilium
Plasma
membrane
Cross-linking
proteins
betw...
© 2014 Pearson Education, Inc.
Figure 4.23ba
(b) Cross section of
motile cilium
Cross-linking
proteins
between outer
doubl...
© 2014 Pearson Education, Inc.
Figure 4.23c
(c) Cross section of basal body
Triplet
0.1 µm
© 2014 Pearson Education, Inc.
Figure 4.23ca
(c) Cross section of basal body
Triplet
0.1 µm
 How dynein “walking” moves flagella and cilia
 Dynein arms alternately grab, move, and release the
outer microtubules
...
Microfilaments (Actin Filaments)
 Microfilaments are thin solid rods, built from
molecules of globular actin subunits
 T...
© 2014 Pearson Education, Inc.
Figure 4.24
Microfilaments
(actin filaments)
0.25 µm Microvillus
Plasma
membrane
 Microfilaments that function in cellular motility
interact with the motor protein myosin
 For example, actin and myosin...
Intermediate Filaments
 Intermediate filaments are larger than
microfilaments but smaller than microtubules
 They suppor...
Concept 4.7: Extracellular components and
connections between cells help coordinate
cellular activities
 Most cells synth...
Cell Walls of Plants
 The cell wall is an extracellular structure that
distinguishes plant cells from animal cells
 Prok...
 Plant cell walls may have multiple layers
 Primary cell wall: relatively thin and flexible
 Middle lamella: thin layer...
© 2014 Pearson Education, Inc.
Figure 4.25
Secondary
cell wall
Central vacuole
Primary
cell wall
1 µm
Middle
lamella
Plasm...
© 2014 Pearson Education, Inc.
Figure 4.25a
Secondary
cell wall
Primary
cell wall
1 µm
Middle
lamella
The Extracellular Matrix (ECM) of Animal Cells
 Animal cells lack cell walls but are covered by an
elaborate extracellula...
© 2014 Pearson Education, Inc.
Figure 4.26
© 2014 Pearson Education, Inc.
Figure 4.26a
© 2014 Pearson Education, Inc.
Figure 4.26b
Cell Junctions
 Neighboring cells in an animal or plant often
adhere, interact, and communicate through direct
physical c...
Plasmodesmata in Plant Cells
 Plasmodesmata are channels that perforate plant
cell walls
 Through plasmodesmata, water a...
Tight Junctions, Desmosomes, and Gap Junctions
in Animal Cells
 Animal cells have three main types of cell junctions
 Ti...
© 2014 Pearson Education, Inc.
Figure 4.27
1 µm
Intermediate
filaments
TEM
0.5 µm
TEM
0.1 µm
TEM
Tight
junction
Tight
junc...
© 2014 Pearson Education, Inc.
Figure 4.27a
Intermediate
filaments
Tight
junction
Ions or small
molecules
Extracellular
ma...
© 2014 Pearson Education, Inc.
Figure 4.27b
0.5 µm
TEM
Tight
junction
© 2014 Pearson Education, Inc.
Figure 4.27c
1 µm
Desmosome (TEM)
© 2014 Pearson Education, Inc.
Figure 4.27d
0.1 µm
Gap junctions
(TEM)
The Cell: A Living Unit Greater Than the Sum of
Its Parts
 Cellular functions arise from cellular order
 For example, a ...
© 2014 Pearson Education, Inc.
Figure 4.28
5µm
© 2014 Pearson Education, Inc.
Figure 4.UN01a
1 µm
Mature parent
cell
Budding
cell
© 2014 Pearson Education, Inc.
Figure 4.UN01b
r
V = π r3
3
4
d
© 2014 Pearson Education, Inc.
Figure 4.UN02
© 2014 Pearson Education, Inc.
Figure 4.UN03
© 2014 Pearson Education, Inc.
Figure 4.UN04
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Biology in Focus Chapter 4

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Biology in Focus Chapter 4 - A Tour of the Cell

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Biology in Focus Chapter 4

  1. 1. CAMPBELL BIOLOGY IN FOCUS © 2014 Pearson Education, Inc. Urry • Cain • Wasserman • Minorsky • Jackson • Reece Lecture Presentations by Kathleen Fitzpatrick and Nicole Tunbridge 4 A Tour of the Cell
  2. 2. Overview: The Fundamental Units of Life  All organisms are made of cells  The cell is the simplest collection of matter that can be alive  All cells are related by their descent from earlier cells  Though cells can differ substantially from one another, they share common features © 2014 Pearson Education, Inc.
  3. 3. © 2014 Pearson Education, Inc. Figure 4.1
  4. 4. Concept 4.1: Biologists use microscopes and the tools of biochemistry to study cells  Most cells are between 1 and 100 µm in diameter, too small to be seen by the unaided eye © 2014 Pearson Education, Inc.
  5. 5. 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 © 2014 Pearson Education, Inc.
  6. 6.  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 between two distinguishable points  Contrast, visible differences in parts of the sample © 2014 Pearson Education, Inc.
  7. 7. © 2014 Pearson Education, Inc. Figure 4.2 Most plant and animal cells Length of some nerve and muscle cells Viruses Smallest bacteria Human height Chicken egg Frog egg Human egg Nucleus Most bacteria Mitochondrion Super- resolution microscopy Atoms Small molecules Ribosomes Proteins Lipids Unaidedeye LM 10 m EM 1 m 0.1 m 1 cm 1 mm 100 µm 10 nm 1 nm 0.1 nm 100 nm 10 µm 1 µm
  8. 8. © 2014 Pearson Education, Inc. Figure 4.2a Length of some nerve and muscle cells Human height Chicken egg Frog egg Human egg Unaidedeye LM 10 m 1 m 0.1 m 1 cm 1 mm 100 µm
  9. 9. © 2014 Pearson Education, Inc. Figure 4.2b Most plant and animal cells Viruses Smallest bacteria Nucleus Most bacteria Mitochondrion Super- resolution microscopy Atoms Small molecules Ribosomes Proteins Lipids EM 100 µm 10 nm 1 nm 0.1 nm 100 nm 10 µm 1 µm LM
  10. 10.  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 light microscopy © 2014 Pearson Education, Inc.
  11. 11.  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 three-dimensional  Transmission electron microscopes (TEMs) focus a beam of electrons through a specimen  TEM is used mainly to study the internal structure of cells © 2014 Pearson Education, Inc.
  12. 12. © 2014 Pearson Education, Inc. Figure 4.3 Scanning electron microscopy (SEM) Transmission electron microscopy (TEM) Longitudinal section of cilium Cross section of cilium Cilia 2 µm 2 µm 50µm 10µm50µm Brightfield (unstained specimen) Electron Microscopy (EM) Fluorescence Brightfield (stained specimen) Differential-interference contrast (Nomarski) Phase-contrast Confocal Light Microscopy (LM)
  13. 13. © 2014 Pearson Education, Inc. Figure 4.3a 50µm Brightfield (unstained specimen) Brightfield (stained specimen) Differential-interference contrast (Nomarski) Phase-contrast Light Microscopy (LM)
  14. 14. © 2014 Pearson Education, Inc. Figure 4.3aa 50µm Brightfield (unstained specimen)
  15. 15. © 2014 Pearson Education, Inc. Figure 4.3ab Brightfield (stained specimen) 50µm
  16. 16. © 2014 Pearson Education, Inc. Figure 4.3ac Phase-contrast 50µm
  17. 17. © 2014 Pearson Education, Inc. Figure 4.3ad Differential-interference contrast (Nomarski) 50µm
  18. 18. © 2014 Pearson Education, Inc. Figure 4.3b 50µm 10µm Fluorescence Confocal Light Microscopy (LM)
  19. 19. © 2014 Pearson Education, Inc. Figure 4.3ba 10µm Fluorescence
  20. 20. © 2014 Pearson Education, Inc. Figure 4.3bb Confocal: without technique 50µm
  21. 21. © 2014 Pearson Education, Inc. Figure 4.3bc Confocal: with technique 50µm
  22. 22. © 2014 Pearson Education, Inc. Figure 4.3c Scanning electron microscopy (SEM) Transmission electron microscopy (TEM) Longitudinal section of cilium Cross section of cilium Cilia 2 µm Electron Microscopy (EM)
  23. 23. © 2014 Pearson Education, Inc. Figure 4.3ca Scanning electron microscopy (SEM) Cilia 2 µm
  24. 24. © 2014 Pearson Education, Inc. Figure 4.3cb Transmission electron microscopy (TEM) Longitudinal section of cilium Cross section of cilium 2 µm
  25. 25.  Recent advances in light microscopy  Labeling molecules or structures with fluorescent markers improves visualization of details  Confocal and other types of microscopy have sharpened images of tissues and cells  New techniques and labeling have improved resolution so that structures as small as 10–20 µm can be distinguished © 2014 Pearson Education, Inc.
  26. 26. Cell Fractionation  Cell fractionation breaks up cells and separates the components, using centrifugation  Cell components separate based on their relative size  Cell fractionation enables scientists to determine the functions of organelles  Biochemistry and cytology help correlate cell function with structure © 2014 Pearson Education, Inc.
  27. 27. Concept 4.2: 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  Organisms of the domains Bacteria and Archaea consist of prokaryotic cells  Protists, fungi, animals, and plants all consist of eukaryotic cells © 2014 Pearson Education, Inc.
  28. 28. Comparing Prokaryotic and Eukaryotic Cells  Basic features of all cells  Plasma membrane  Semifluid substance called cytosol  Chromosomes (carry genes)  Ribosomes (make proteins) © 2014 Pearson Education, Inc.
  29. 29.  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 © 2014 Pearson Education, Inc.
  30. 30. © 2014 Pearson Education, Inc. Figure 4.4 (a) A typical rod-shaped bacterium 0.5 µm (b) A thin section through the bacterium Bacillus coagulans (TEM) Bacterial chromosome Fimbriae Nucleoid Ribosomes Cell wall Plasma membrane Capsule Flagella
  31. 31. © 2014 Pearson Education, Inc. Figure 4.4a 0.5 µm (b) A thin section through the bacterium Bacillus coagulans (TEM) Nucleoid Ribosomes Cell wall Plasma membrane Capsule
  32. 32.  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 © 2014 Pearson Education, Inc.
  33. 33.  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 © 2014 Pearson Education, Inc.
  34. 34. © 2014 Pearson Education, Inc. Figure 4.5 0.1 µm (a) TEM of a plasma membraneOutside of cell (b) Structure of the plasma membrane Inside of cell Hydrophilic region Hydrophilic region Hydrophobic region Carbohydrate side chains Phospholipid Proteins
  35. 35. © 2014 Pearson Education, Inc. Figure 4.5a 0.1 µm (a) TEM of a plasma membrane Outside of cell Inside of cell
  36. 36. © 2014 Pearson Education, Inc. Figure 4.5b (b) Structure of the plasma membrane Hydrophilic region Hydrophilic region Hydrophobic region Carbohydrate side chains Phospholipid Proteins
  37. 37.  Metabolic requirements set upper limits on the size of cells  The ratio of surface area to volume 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 © 2014 Pearson Education, Inc.
  38. 38. © 2014 Pearson Education, Inc. Figure 4.6 750 Surface area increases while total volume remains constant 125 150 125 6 1 6 1 61.2 5 1 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 ratio [surface area ÷ volume]
  39. 39. A Panoramic View of the Eukaryotic Cell  A eukaryotic cell has internal membranes that divide the cell into compartments—organelles  The plasma membrane and organelle membranes participate directly in the cell’s metabolism © 2014 Pearson Education, Inc. Animation: Tour of a Plant Cell Animation: Tour of an Animal Cell
  40. 40. © 2014 Pearson Education, Inc. Figure 4.7a CYTOSKELETON: NUCLEUS ENDOPLASMIC RETICULUM (ER) Smooth ER Rough ERFlagellum Centrosome Microfilaments Intermediate filaments Microvilli Microtubules Mitochondrion Peroxisome Golgi apparatus Lysosome Plasma membrane Ribosomes Nucleolus Nuclear envelope Chromatin
  41. 41. © 2014 Pearson Education, Inc. Figure 4.7b CYTO- SKELETON NUCLEUS Smooth endoplasmic reticulum Chloroplast Central vacuole Microfilaments Intermediate filaments Cell wall Microtubules Mitochondrion Peroxisome Golgi apparatus Plasmodesmata Plasma membrane Ribosomes Nucleolus Nuclear envelope Chromatin Wall of adjacent cell Rough endoplasmic reticulum
  42. 42. © 2014 Pearson Education, Inc. Figure 4.7c Nucleolus Nucleus Cell 10µm Human cells from lining of uterus (colorized TEM)
  43. 43. © 2014 Pearson Education, Inc. Figure 4.7d 5µm Parent cell Buds Yeast cells budding (colorized SEM)
  44. 44. © 2014 Pearson Education, Inc. Figure 4.7e 1 µm A single yeast cell (colorized TEM) Mitochondrion Nucleus Vacuole Cell wall
  45. 45. © 2014 Pearson Education, Inc. Figure 4.7f 5µm Cell wall Cell Chloroplast Mitochondrion Nucleus Nucleolus Cells from duckweed (colorized TEM)
  46. 46. © 2014 Pearson Education, Inc. Figure 4.7g 8µm Chlamydomonas (colorized SEM)
  47. 47. © 2014 Pearson Education, Inc. Figure 4.7h 1µm Chlamydomonas (colorized TEM) Cell wall Flagella Chloroplast Vacuole Nucleus Nucleolus
  48. 48. Concept 4.3: 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 © 2014 Pearson Education, Inc.
  49. 49. 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 © 2014 Pearson Education, Inc.
  50. 50.  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 © 2014 Pearson Education, Inc.
  51. 51. © 2014 Pearson Education, Inc. Figure 4.8 Ribosome 1 µm Chromatin Rough ER Nucleus Nucleolus Nucleus Chromatin 0.5µm 0.25µm Nuclear envelope: Nuclear pore Inner membrane Outer membrane Pore complex Close-up of nuclear envelope Nuclear lamina (TEM) Surface of nuclear envelope Pore complexes (TEM)
  52. 52. © 2014 Pearson Education, Inc. Figure 4.8a Ribosome Chromatin Rough ER Nucleus Nucleolus Chromatin Nuclear envelope: Nuclear pore Inner membrane Outer membrane Pore complex Close-up of nuclear envelope
  53. 53. © 2014 Pearson Education, Inc. Figure 4.8b 1 µm Nuclear envelope: Nuclear pore Inner membrane Outer membrane Surface of nuclear envelope
  54. 54. © 2014 Pearson Education, Inc. Figure 4.8c 0.25µm Pore complexes (TEM)
  55. 55. © 2014 Pearson Education, Inc. Figure 4.8d 0.5µm Nuclear lamina (TEM)
  56. 56.  In the nucleus, DNA is organized into discrete units called chromosomes  Each chromosome is one long 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 © 2014 Pearson Education, Inc.
  57. 57. Ribosomes: Protein Factories  Ribosomes are complexes 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) © 2014 Pearson Education, Inc.
  58. 58. © 2014 Pearson Education, Inc. Figure 4.9 TEM showing ER and ribosomes Diagram of a ribosome Ribosomes bound to ER Free ribosomes in cytosol Endoplasmic reticulum (ER) Ribosomes ER 0.25 µm Large subunit Small subunit
  59. 59. © 2014 Pearson Education, Inc. Figure 4.9a TEM showing ER and ribosomes Ribosomes bound to ER Free ribosomes in cytosol Endoplasmic reticulum (ER) 0.25 µm
  60. 60. Concept 4.4: 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 through transfer by vesicles © 2014 Pearson Education, Inc.
  61. 61. 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: lacks ribosomes  Rough ER: surface is studded with ribosomes © 2014 Pearson Education, Inc. Video: Endoplasmic Reticulum Video: ER and Mitochondria
  62. 62. © 2014 Pearson Education, Inc. Figure 4.10 Transport vesicle Smooth ER Rough ER Ribosomes Transitional ER Cisternae ER lumen Smooth ER Rough ER Nuclear envelope 0.2 µm
  63. 63. © 2014 Pearson Education, Inc. Figure 4.10a Transport vesicle Smooth ER Rough ER Ribosomes Transitional ER Cisternae ER lumen Nuclear envelope
  64. 64. © 2014 Pearson Education, Inc. Figure 4.10b Smooth ER Rough ER 0.2 µm
  65. 65. Functions of Smooth ER  The smooth ER  Synthesizes lipids  Metabolizes carbohydrates  Detoxifies drugs and poisons  Stores calcium ions © 2014 Pearson Education, Inc.
  66. 66. 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 © 2014 Pearson Education, Inc.
  67. 67.  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 © 2014 Pearson Education, Inc. Video: Golgi 3-D Video: Golgi Secretion Video: ER to Golgi Traffic
  68. 68. © 2014 Pearson Education, Inc. Figure 4.11 TEM of Golgi apparatus Golgi apparatus trans face (“shipping” side of Golgi apparatus) Cisternae 0.1 µm cis face (“receiving” side of Golgi apparatus)
  69. 69. © 2014 Pearson Education, Inc. Figure 4.11a trans face (“shipping” side of Golgi apparatus) Cisternae cis face (“receiving” side of Golgi apparatus)
  70. 70. © 2014 Pearson Education, Inc. Figure 4.11b TEM of Golgi apparatus 0.1 µm
  71. 71. 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 © 2014 Pearson Education, Inc.
  72. 72. Animation: Lysosome Formation Video: Phagocytosis  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 © 2014 Pearson Education, Inc. Video: Paramecium Vacuole
  73. 73. © 2014 Pearson Education, Inc. Figure 4.12 Lysosome 1 µmNucleus Lysosome Digestive enzymes Plasma membrane Food vacuole Lysosomes: Phagocytosis Digestion
  74. 74. © 2014 Pearson Education, Inc. Figure 4.12a Lysosome Digestive enzymes Plasma membrane Food vacuole Lysosomes: Phagocytosis Digestion
  75. 75. © 2014 Pearson Education, Inc. Figure 4.12b Lysosome 1 µmNucleus
  76. 76. © 2014 Pearson Education, Inc. Figure 4.13 Lysosome Lysosomes: Autophagy Peroxisome Mitochondrion Vesicle Digestion Mitochondrion fragment Peroxisome fragment Vesicle containing two damaged organelles 1 µm
  77. 77. © 2014 Pearson Education, Inc. Figure 4.13a Lysosome Lysosomes: Autophagy Peroxisome Mitochondrion Vesicle Digestion
  78. 78. © 2014 Pearson Education, Inc. Figure 4.13b Mitochondrion fragment Peroxisome fragment Vesicle containing two damaged organelles 1 µm
  79. 79. Vacuoles: Diverse Maintenance Compartments  Vacuoles are large vesicles derived from the endoplasmic reticulum and Golgi apparatus © 2014 Pearson Education, Inc.
  80. 80.  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  Certain vacuoles in plants and fungi carry out enzymatic hydrolysis like lysosomes © 2014 Pearson Education, Inc.
  81. 81. © 2014 Pearson Education, Inc. Figure 4.14 Central vacuole Central vacuole Chloroplast Cytosol Cell wall Nucleus Plant cell vacuole 5 µm
  82. 82. © 2014 Pearson Education, Inc. Figure 4.14a Central vacuole Chloroplast Cytosol Cell wall Nucleus Plant cell vacuole 5 µm
  83. 83. The Endomembrane System: A Review  The endomembrane system is a complex and dynamic player in the cell’s compartmental organization © 2014 Pearson Education, Inc.
  84. 84. © 2014 Pearson Education, Inc. Figure 4.15-1 Rough ER Nucleus Smooth ER Plasma membrane
  85. 85. © 2014 Pearson Education, Inc. Figure 4.15-2 Plasma membrane Rough ER cis Golgi Nucleus Smooth ER trans Golgi
  86. 86. © 2014 Pearson Education, Inc. Figure 4.15-3 Plasma membrane Rough ER cis Golgi Nucleus Smooth ER trans Golgi
  87. 87. Concept 4.5: 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 © 2014 Pearson Education, Inc.
  88. 88.  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 The Evolutionary Origins of Mitochondria and Chloroplasts © 2014 Pearson Education, Inc.
  89. 89.  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 © 2014 Pearson Education, Inc. Video: ER and Mitochondria Video: Mitochondria 3-D
  90. 90. © 2014 Pearson Education, Inc. Figure 4.16 Mitochondrion Mitochondrion Nonphotosynthetic eukaryote Photosynthetic eukaryote At least one cell Chloroplast Engulfing of photosynthetic prokaryote Nucleus Nuclear envelope Endoplasmic reticulum Ancestor of eukaryotic cells (host cell) Engulfing of oxygen- using nonphotosynthetic prokaryote, which becomes a mitochondrion
  91. 91. 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 © 2014 Pearson Education, Inc.
  92. 92. © 2014 Pearson Education, Inc. Figure 4.17 Free ribosomes in the mitochondrial matrix Mitochondrion Intermembrane space Matrix Cristae DNA Outer membrane Inner membrane 0.1 µm
  93. 93. © 2014 Pearson Education, Inc. Figure 4.17a Matrix Cristae Outer membrane Inner membrane 0.1 µm
  94. 94. 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 © 2014 Pearson Education, Inc.
  95. 95.  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 © 2014 Pearson Education, Inc.
  96. 96. © 2014 Pearson Education, Inc. Figure 4.18 Intermembrane space Ribosomes Inner and outer membranes 1 µm Stroma Granum DNA Chloroplast Thylakoid (a) Diagram and TEM of chloroplast 50 µm (b) Chloroplasts in an algal cell Chloroplasts (red)
  97. 97. © 2014 Pearson Education, Inc. Figure 4.18a Intermembrane space Ribosomes Inner and outer membranes 1 µm Stroma Granum DNA Thylakoid (a) Diagram and TEM of chloroplast
  98. 98. © 2014 Pearson Education, Inc. Figure 4.18aa Inner and outer membranes 1 µm Stroma Granum
  99. 99. © 2014 Pearson Education, Inc. Figure 4.18b 50 µm (b) Chloroplasts in an algal cell Chloroplasts (red)
  100. 100. 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 © 2014 Pearson Education, Inc. Video: Cytoskeleton in Neuron
  101. 101. © 2014 Pearson Education, Inc. Figure 4.19 Chloroplast 1 µm Peroxisome Mitochondrion
  102. 102. Concept 4.6: 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 © 2014 Pearson Education, Inc. Video: Organelle Movement Video: Organelle Transport Video: Microtubule Transport
  103. 103. © 2014 Pearson Education, Inc. Figure 4.20 10µm
  104. 104. 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 and other organelles can “walk” along the tracks provided by the cytoskeleton © 2014 Pearson Education, Inc.
  105. 105. © 2014 Pearson Education, Inc. Figure 4.21 Microtubule Vesicles (b) SEM of a squid giant axon Receptor for motor protein 0.25 µm Vesicle Motor protein (ATP powered) ATP Microtubule of cytoskeleton (a) Motor proteins “walk” vesicles along cytoskeletal fibers.
  106. 106. © 2014 Pearson Education, Inc. Figure 4.21a Microtubule Vesicles (b) SEM of a squid giant axon 0.25 µm
  107. 107. 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 © 2014 Pearson Education, Inc.
  108. 108. © 2014 Pearson Education, Inc. Video: Actin in Crawling Cell Video: Actin in Neuron Video: Actin Cytoskeleton Video: Cytoplasmic Stream Video: Microtubule Movement Video: Chloroplast Movement Video: Microtubules
  109. 109. © 2014 Pearson Education, Inc. Table 4.1
  110. 110. © 2014 Pearson Education, Inc. Table 4.1a Column of tubulin dimers Microtubules 25 nm Tubulin dimerβα
  111. 111. © 2014 Pearson Education, Inc. Table 4.1b Actin subunit Microfilaments 7 nm
  112. 112. © 2014 Pearson Education, Inc. Table 4.1c Keratin proteins Fibrous subunit (keratins coiled together) Intermediate filaments 8–12 nm
  113. 113. Microtubules  Microtubules are hollow rods constructed from globular protein dimers called tubulin  Functions of microtubules  Shape and support the cell  Guide movement of organelles  Separate chromosomes during cell division © 2014 Pearson Education, Inc.
  114. 114. Centrosomes and Centrioles  In animal cells, microtubules grow out from a centrosome near the nucleus  The centrosome is a “microtubule-organizing center”  The centrosome has a pair of centrioles, each with nine triplets of microtubules arranged in a ring © 2014 Pearson Education, Inc.
  115. 115. © 2014 Pearson Education, Inc. Animation: Cilia Flagella Video: Ciliary Motion Video: Chlamydomonas Video: Flagellum Microtubule Video: Sperm Flagellum Video: Flagella in Sperm Video: Paramecium Cilia
  116. 116. © 2014 Pearson Education, Inc. Figure 4.22 Microtubule Centrioles Centrosome
  117. 117. Cilia and Flagella  Microtubules control the beating of cilia and flagella, microtubule-containing extensions projecting from some cells  Flagella are limited to one or a few per cell, while cilia occur in large numbers on cell surfaces  Cilia and flagella also differ in their beating patterns © 2014 Pearson Education, Inc.
  118. 118.  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 © 2014 Pearson Education, Inc.
  119. 119. © 2014 Pearson Education, Inc. Figure 4.23 Plasma membrane Microtubules Basal body (a) Longitudinal section of motile cilium (c) Cross section of basal body (b) Cross section of motile cilium Triplet Plasma membrane Cross-linking proteins between outer doublets Radial spoke Central microtubule Outer microtubule doublet Dynein proteins 0.1 µm 0.5 µm 0.1 µm
  120. 120. © 2014 Pearson Education, Inc. Figure 4.23a Plasma membrane Microtubules Basal body (a) Longitudinal section of motile cilium 0.5 µm
  121. 121. © 2014 Pearson Education, Inc. Figure 4.23b (b) Cross section of motile cilium Plasma membrane Cross-linking proteins between outer doublets Radial spoke Central microtubule Outer microtubule doublet Dynein proteins 0.1 µm
  122. 122. © 2014 Pearson Education, Inc. Figure 4.23ba (b) Cross section of motile cilium Cross-linking proteins between outer doublets Radial spoke Central microtubule Dynein proteins 0.1 µm Outer microtubule doublet
  123. 123. © 2014 Pearson Education, Inc. Figure 4.23c (c) Cross section of basal body Triplet 0.1 µm
  124. 124. © 2014 Pearson Education, Inc. Figure 4.23ca (c) Cross section of basal body Triplet 0.1 µm
  125. 125.  How dynein “walking” moves flagella and cilia  Dynein arms alternately grab, move, and release the outer microtubules  The outer doublets and central microtubules are held together by flexible cross-linking proteins  Movements of the doublet arms cause the cilium or flagellum to bend © 2014 Pearson Education, Inc.
  126. 126. Microfilaments (Actin Filaments)  Microfilaments are thin solid rods, built from molecules of globular actin subunits  The structural role of microfilaments is to bear tension, resisting pulling forces within the cell  Bundles of microfilaments make up the core of microvilli of intestinal cells © 2014 Pearson Education, Inc.
  127. 127. © 2014 Pearson Education, Inc. Figure 4.24 Microfilaments (actin filaments) 0.25 µm Microvillus Plasma membrane
  128. 128.  Microfilaments that function in cellular motility interact with the motor protein myosin  For example, actin and myosin interact to cause muscle contraction, amoeboid movement of white blood cells, and cytoplasmic streaming in plant cells © 2014 Pearson Education, Inc.
  129. 129. Intermediate Filaments  Intermediate filaments are larger than microfilaments but smaller than microtubules  They support cell shape and fix organelles in place  Intermediate filaments are more permanent cytoskeleton elements than the other two classes © 2014 Pearson Education, Inc.
  130. 130. Concept 4.7: 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 materials are involved in many cellular functions © 2014 Pearson Education, Inc.
  131. 131. 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 © 2014 Pearson Education, Inc.
  132. 132.  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 © 2014 Pearson Education, Inc. Video: Extracellular Matrix Video: Fibronectin Video: Collagen Model
  133. 133. © 2014 Pearson Education, Inc. Figure 4.25 Secondary cell wall Central vacuole Primary cell wall 1 µm Middle lamella Plasmodesmata Cytosol Plasma membrane Plant cell walls
  134. 134. © 2014 Pearson Education, Inc. Figure 4.25a Secondary cell wall Primary cell wall 1 µm Middle lamella
  135. 135. 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 © 2014 Pearson Education, Inc.
  136. 136. © 2014 Pearson Education, Inc. Figure 4.26
  137. 137. © 2014 Pearson Education, Inc. Figure 4.26a
  138. 138. © 2014 Pearson Education, Inc. Figure 4.26b
  139. 139. Cell Junctions  Neighboring cells in an animal or plant often adhere, interact, and communicate through direct physical contact  There are several types of intercellular junctions that facilitate this  Plasmodesmata  Tight junctions  Desmosomes  Gap junctions © 2014 Pearson Education, Inc.
  140. 140. 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 © 2014 Pearson Education, Inc.
  141. 141. Tight Junctions, Desmosomes, and Gap Junctions in Animal Cells  Animal cells have three main types of cell junctions  Tight junctions  Desmosomes  Gap junctions  All are especially common in epithelial tissue © 2014 Pearson Education, Inc. Animation: Gap Junctions Animation: Tight Junctions Animation: Desmosomes
  142. 142. © 2014 Pearson Education, Inc. Figure 4.27 1 µm Intermediate filaments TEM 0.5 µm TEM 0.1 µm TEM Tight junction Tight junction Ions or small molecules Extracellular matrix Gap junction Desmosome Space between cells Plasma membranes of adjacent cells Tight junctions prevent fluid from moving across a layer of cells
  143. 143. © 2014 Pearson Education, Inc. Figure 4.27a Intermediate filaments Tight junction Ions or small molecules Extracellular matrix Gap junction Desmosome Space between cells Plasma membranes of adjacent cells Tight junctions prevent fluid from moving across a layer of cells
  144. 144. © 2014 Pearson Education, Inc. Figure 4.27b 0.5 µm TEM Tight junction
  145. 145. © 2014 Pearson Education, Inc. Figure 4.27c 1 µm Desmosome (TEM)
  146. 146. © 2014 Pearson Education, Inc. Figure 4.27d 0.1 µm Gap junctions (TEM)
  147. 147. The Cell: A Living Unit Greater Than the Sum of Its Parts  Cellular functions arise from cellular order  For example, a macrophage’s ability to destroy bacteria involves the whole cell, coordinating components such as the cytoskeleton, lysosomes, and plasma membrane © 2014 Pearson Education, Inc.
  148. 148. © 2014 Pearson Education, Inc. Figure 4.28 5µm
  149. 149. © 2014 Pearson Education, Inc. Figure 4.UN01a 1 µm Mature parent cell Budding cell
  150. 150. © 2014 Pearson Education, Inc. Figure 4.UN01b r V = π r3 3 4 d
  151. 151. © 2014 Pearson Education, Inc. Figure 4.UN02
  152. 152. © 2014 Pearson Education, Inc. Figure 4.UN03
  153. 153. © 2014 Pearson Education, Inc. Figure 4.UN04

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