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- 1. PowerPoint Lectures
Campbell Biology: Concepts & Connections, 8th Edition, Global Edition
REECE • TAYLOR • SIMON • DICKEY • HOGAN
Lecture by Edward J. Zalisko
Chapter 4
A Tour of the Cell
© 2016 Pearson Education, Ltd.
- 2. Introduction
• Cells have a cytoskeleton that
• provides support and
• allows some cells to crawl and others to swim.
• Our understanding of nature often goes hand in
hand with the invention and refinement of
instruments that extend our senses.
© 2016 Pearson Education, Ltd.
- 3. Introduction
• In 1665, Hooke examined a piece of cork under a
crude microscope and identified “little rooms” as
cells.
• Leeuwenhoek, working at about the same time,
used more refined lenses to describe living cells
from blood, sperm, and pond water.
• Since the days of Hooke and Leeuwenhoek,
improved microscopes have vastly expanded our
view of the cell.
© 2016 Pearson Education, Ltd.
- 5. Figure 4.0-2
Introduction to the Cell
Chapter 4: Big Ideas
The Nucleus and
Ribosomes
The Endomembrane
System
Energy-Converting
Organelles
The Cytoskeleton and
Cell Surfaces
© 2016 Pearson Education, Ltd.
- 7. 4.1 Microscopes reveal the world of the cell
• A variety of microscopes have been developed for
a clearer view of cells and cellular structure.
• The first microscopes were light microscopes. In a
light microscope (LM), visible light passes
through a specimen, then through glass lenses,
and finally is projected into the viewer’s eye.
• Specimens can be magnified by up to 1,000 times.
© 2016 Pearson Education, Ltd.
- 8. 4.1 Microscopes reveal the world of the cell
• Magnification is the increase in an object’s image
size compared with its actual size.
• Resolution is a measure of the clarity of an image.
In other words, it is the ability of an instrument to
show two nearby objects as separate.
© 2016 Pearson Education, Ltd.
- 9. 4.1 Microscopes reveal the world of the cell
• Microscopes have limitations.
• The human eye and the microscope have limits of
resolution—the ability to distinguish between small
structures.
• Therefore, the light microscope cannot provide the
details of a small cell’s structure.
© 2016 Pearson Education, Ltd.
- 10. 4.1 Microscopes reveal the world of the cell
• Using light microscopes, scientists studied
• microorganisms,
• animal and plant cells, and
• some structures within cells.
• In the 1800s, these studies led to cell theory,
which states that
• all living things are composed of cells and
• all cells come from other cells.
© 2016 Pearson Education, Ltd.
- 15. Figure 4.1e-0
Human height
Length of some
nerve and
muscle cells
Chicken egg
Frog egg
Paramecium
Human egg
Most plant and
animal cells
Nucleus
Most bacteria
Mitochondrion
Smallest bacteria
Viruses
Ribosome
Proteins
Lipids
Small
molecules
Atoms
Unaidedeye
Lightmicroscope
Electronmicroscope
10 m
1 m
100 mm
(10 cm)
10 mm
(1 cm)
1 mm
100 nm
10 nm
1 nm
0.1 nm
100 μm
10 μm
1 μm
© 2016 Pearson Education, Ltd.
- 16. Figure 4.1e-1
Human height
Length of some
nerve and
muscle cells
Chicken egg
Frog egg
Paramecium
Human egg
Unaidedeye
10 m
1 m
100 mm
(10 cm)
10 mm
(1 cm)
1 mm
100 μm
© 2016 Pearson Education, Ltd.
- 17. Figure 4.1e-2
Frog egg
Paramecium
Human egg
Most plant and
animal cells
Nucleus
Most bacteria
Mitochondrion
Smallest bacteria
Viruses
Ribosome
Proteins
Lipids
Small
molecules
Atoms
Lightmicroscope
Electronmicroscope
1 mm
100 nm
10 nm
1 nm
0.1 nm
100 μm
10 μm
1 μm
© 2016 Pearson Education, Ltd.
- 18. 4.1 Microscopes reveal the world of the cell
• Beginning in the 1950s, scientists started using a
very powerful microscope called the electron
microscope (EM) to view the ultrastructure of
cells.
• Instead of light, EM uses a beam of electrons.
• Electron microscopes can
• resolve biological structures as small as 2
nanometers and
• magnify up to 100,000 times.
© 2016 Pearson Education, Ltd.
- 19. 4.1 Microscopes reveal the world of the cell
• Scanning electron microscopes (SEMs) study
the detailed architecture of cell surfaces.
• Transmission electron microscopes (TEMs)
study the details of internal cell structure.
• Differential interference light microscopes amplify
differences in density so that structures in living
cells appear almost three-dimensional.
© 2016 Pearson Education, Ltd.
- 20. 4.2 The small size of cells relates to the need
to exchange materials across the plasma
membrane
• Cell size must
• be large enough to house DNA, proteins, and
structures needed to survive and reproduce, but
• remain small enough to allow for a surface-to-
volume ratio that will allow adequate exchange with
the environment.
© 2016 Pearson Education, Ltd.
- 22. 4.2 The small size of cells relates to the need
to exchange materials across the plasma
membrane
• The plasma membrane forms a flexible boundary
between the living cell and its surroundings.
• Phospholipids form a two-layer sheet called a
phospholipid bilayer in which
• hydrophilic heads face outward, exposed to water,
and
• hydrophobic tails point inward, shielded from water.
© 2016 Pearson Education, Ltd.
- 23. 4.2 The small size of cells relates to the need
to exchange materials across the plasma
membrane
• Membrane proteins are embedded in the lipid
bilayer.
• Some proteins form channels (tunnels) that shield
ions and other hydrophilic molecules as they pass
through the hydrophobic center of the membrane.
• Other proteins serve as pumps, using energy to
actively transport molecules into or out of the cell.
© 2016 Pearson Education, Ltd.
- 24. Figure 4.2b
Outside cell
Inside cell
Hydrophilic
heads
Hydrophobic
tails
Phospholipid
Channel
protein
Hydrophilic
regions of
a protein
Hydrophobic
regions of
a protein
© 2016 Pearson Education, Ltd.
- 26. 4.3 Prokaryotic cells are structurally simpler
than eukaryotic cells
• Bacteria and archaea are prokaryotic cells.
• All other forms of life are composed of eukaryotic
cells.
• Eukaryotic cells are distinguished by having
• a membrane-enclosed nucleus and
• many membrane-enclosed organelles that perform
specific functions.
• Prokaryotic cells are smaller and simpler in
structure.
© 2016 Pearson Education, Ltd.
- 27. 4.3 Prokaryotic cells are structurally simpler
than eukaryotic cells
• Prokaryotic and eukaryotic cells have
• a plasma membrane,
• an interior filled with a thick, jellylike fluid called the
cytosol,
• one or more chromosomes, which carry genes
made of DNA, and
• ribosomes, tiny structures that make proteins
according to instructions from the genes.
© 2016 Pearson Education, Ltd.
- 28. 4.3 Prokaryotic cells are structurally simpler
than eukaryotic cells
• The inside of both types of cells is called the
cytoplasm.
• However, in eukaryotic cells, this term refers only
to the region between the nucleus and the plasma
membrane.
© 2016 Pearson Education, Ltd.
- 29. 4.3 Prokaryotic cells are structurally simpler
than eukaryotic cells
• In a prokaryotic cell,
• the DNA is coiled into a region called the nucleoid
(nucleus-like) and
• no membrane surrounds the DNA.
© 2016 Pearson Education, Ltd.
- 30. 4.3 Prokaryotic cells are structurally simpler
than eukaryotic cells
• Outside the plasma membrane of most prokaryotes
is a fairly rigid, chemically complex cell wall, which
• protects the cell and
• helps maintain its shape.
• Some prokaryotes have surface projections.
• Short projections help attach prokaryotes to each
other or their substrate.
• Longer projections called flagella (singular,
flagellum) propel a prokaryotic cell through its liquid
environment.
© 2016 Pearson Education, Ltd.
- 34. 4.4 Eukaryotic cells are partitioned into
functional compartments
• A eukaryotic cell contains
• a membrane-enclosed nucleus and
• various other organelles (“little organs”), which
perform specific functions in the cell.
© 2016 Pearson Education, Ltd.
- 35. 4.4 Eukaryotic cells are partitioned into
functional compartments
• The structures and organelles of eukaryotic cells
perform four basic functions.
1. The nucleus and ribosomes are involved in the
genetic control of the cell.
2. The endoplasmic reticulum, Golgi apparatus,
lysosomes, vacuoles, and peroxisomes are
involved in the manufacture, distribution, and
breakdown of molecules.
© 2016 Pearson Education, Ltd.
- 36. 4.4 Eukaryotic cells are partitioned into
functional compartments
3. Mitochondria in all cells and chloroplasts in plant
cells are involved in energy processing.
4. Structural support, movement, and
communication between cells are functions of
the cytoskeleton, plasma membrane, and cell
wall.
© 2016 Pearson Education, Ltd.
- 37. 4.4 Eukaryotic cells are partitioned into
functional compartments
• The internal membranes of eukaryotic cells
partition it into compartments.
• Cellular metabolism, the many chemical activities
of cells, occurs within organelles.
© 2016 Pearson Education, Ltd.
- 38. 4.4 Eukaryotic cells are partitioned into
functional compartments
• Almost all of the organelles and other structures of
animals cells are present in plant cells.
• A few exceptions exist.
• Lysosomes and centrosomes containing centrioles
are not found in plant cells.
• Only the sperm cells of a few plant species have
flagella.
© 2016 Pearson Education, Ltd.
- 39. 4.4 Eukaryotic cells are partitioned into
functional compartments
• Plant but not animal cells have
• a rigid cell wall that contains cellulose,
• plasmodesmata, cytoplasmic channels through cell
walls that connect adjacent cells,
• chloroplasts, where photosynthesis occurs, and
• a central vacuole, a compartment that stores water
and a variety of chemicals.
© 2016 Pearson Education, Ltd.
- 43. 4.5 The nucleus contains the cell’s genetic
instructions
• The nucleus
• contains most of the cell’s DNA and
• controls the cell’s activities by directing protein
synthesis by making messenger RNA (mRNA).
• DNA is associated with many proteins and is
organized into structures called chromosomes.
• When a cell is not dividing, this complex of proteins
and DNA, called chromatin, appears as a diffuse
mass within the nucleus.
© 2016 Pearson Education, Ltd.
- 44. 4.5 The nucleus contains the cell’s genetic
instructions
• The double membrane nuclear envelope has
pores that
• regulate the entry and exit of large molecules and
• connect with the cell’s network of membranes
called the endoplasmic reticulum.
© 2016 Pearson Education, Ltd.
- 45. 4.5 The nucleus contains the cell’s genetic
instructions
• The nucleolus is
• a prominent structure in the nucleus and
• the site of ribosomal RNA (rRNA) synthesis.
© 2016 Pearson Education, Ltd.
- 47. 4.6 Ribosomes make proteins for use in the
cell and export
• Ribosomes are involved in the cell’s protein
synthesis.
• Ribosomes are the cellular components that use
instructions from the nucleus, written in mRNA, to
build proteins.
• Cells that make a lot of proteins have a large
number of ribosomes.
© 2016 Pearson Education, Ltd.
- 48. 4.6 Ribosomes make proteins for use in the
cell and export
• Some ribosomes are free ribosomes; others are
bound.
• Free ribosomes are suspended in the cytosol.
• Bound ribosomes are attached to the outside of the
endoplasmic reticulum or nuclear envelope.
© 2016 Pearson Education, Ltd.
- 49. Figure 4.6
Rough ER
Bound ribosome
Endoplasmic
reticulum
Protein
Ribosome
Free ribosome
mRNA
© 2016 Pearson Education, Ltd.
- 51. 4.7 Many organelles are connected in the
endomembrane system
• Many of the membranes within a eukaryotic cell
are part of the endomembrane system.
• Some of these membranes are physically
connected, and others are linked when tiny
vesicles (sacs made of membrane) transfer
membrane segments between them.
© 2016 Pearson Education, Ltd.
- 52. 4.7 Many organelles are connected in the
endomembrane system
• Many of these organelles interact in the
• synthesis,
• distribution,
• storage, and
• export of molecules.
© 2016 Pearson Education, Ltd.
- 53. 4.7 Many organelles are connected in the
endomembrane system
• The endomembrane system includes the
• nuclear envelope,
• endoplasmic reticulum (ER),
• Golgi apparatus,
• lysosomes,
• vacuoles, and
• plasma membrane.
© 2016 Pearson Education, Ltd.
- 54. 4.7 Many organelles are connected in the
endomembrane system
• The largest component of the endomembrane
system is the endoplasmic reticulum (ER), an
extensive network of flattened sacs and tubules.
© 2016 Pearson Education, Ltd.
- 55. 4.8 The endoplasmic reticulum is a
biosynthetic workshop
• There are two kinds of endoplasmic reticulum,
which differ in structure and function.
1. Smooth ER lacks attached ribosomes.
2. Rough ER has bound ribosomes that stud the
outer surface of the membrane.
© 2016 Pearson Education, Ltd.
- 58. 4.8 The endoplasmic reticulum is a
biosynthetic workshop
• Smooth ER is involved in a variety of metabolic
processes, including
• the production of enzymes important in the
synthesis of lipids, oils, phospholipids, and steroids,
• the production of enzymes that help process drugs,
alcohol, and other potentially harmful substances,
and
• the storage of calcium ions.
© 2016 Pearson Education, Ltd.
- 59. 4.8 The endoplasmic reticulum is a
biosynthetic workshop
• Rough ER makes
• additional membrane for itself and
• secretory proteins.
© 2016 Pearson Education, Ltd.
- 60. 4.9 The Golgi apparatus modifies, sorts, and
ships cell products
• The Golgi apparatus serves as a molecular
warehouse and processing station for products
manufactured by the ER.
• Products travel in transport vesicles from the ER to
the Golgi apparatus.
• One side of the Golgi stack serves as a receiving
dock for transport vesicles produced by the ER.
© 2016 Pearson Education, Ltd.
- 61. 4.9 The Golgi apparatus modifies, sorts, and
ships cell products
• Products of the ER are modified as a Golgi sac
progresses through the stack.
• The “shipping” side of the Golgi functions as a
depot, where products in vesicles bud off and travel
to other sites.
© 2016 Pearson Education, Ltd.© 2012 Pearson Education, Inc.
- 63. 4.10 Lysosomes are digestive compartments
within a cell
• A lysosome is a membrane-enclosed sac of
digestive enzymes
• made by rough ER and
• processed in the Golgi apparatus
© 2016 Pearson Education, Ltd.
- 64. 4.10 Lysosomes are digestive compartments
within a cell
• Lysosomes
• fuse with food vacuoles and digest food,
• destroy bacteria engulfed by white blood cells, or
• fuse with other vesicles containing damaged
organelles or other materials to be recycled within a
cell.
© 2016 Pearson Education, Ltd.
- 73. 4.11 Vacuoles function in the general
maintenance of the cell
• Vacuoles are large vesicles that have a variety of
functions.
• Some protists have contractile vacuoles, which help
to eliminate water from the protist.
• In plants, vacuoles may
• have digestive functions,
• contain pigments, or
• contain poisons that protect the plant.
© 2016 Pearson Education, Ltd.
- 77. 4.12 A review of the structures involved in
manufacturing and breakdown
• The following figure summarizes the relationships
among the major organelles of the endomembrane
system.
© 2016 Pearson Education, Ltd.
- 79. 4.12 A review of the structures involved in
manufacturing and breakdown
• Peroxisomes are metabolic compartments that do
not originate from the endomembrane system.
• How they are related to other organelles is still
unknown.
• Some peroxisomes break down fatty acids to be
used as cellular fuel.
© 2016 Pearson Education, Ltd.
- 81. 4.13 Mitochondria harvest chemical energy
from food
• Mitochondria are organelles that carry out cellular
respiration in nearly all eukaryotic cells.
• Cellular respiration converts the chemical energy
in foods to chemical energy in ATP (adenosine
triphosphate).
© 2016 Pearson Education, Ltd.
- 82. 4.13 Mitochondria harvest chemical energy
from food
• Mitochondria have two internal compartments.
1. The intermembrane space is the narrow region
between the inner and outer membranes.
2. The mitochondrial matrix contains
• the mitochondrial DNA,
• ribosomes, and
• many enzymes that catalyze some of the reactions
of cellular respiration.
© 2016 Pearson Education, Ltd.
- 83. 4.13 Mitochondria harvest chemical energy
from food
• Folds of the inner mitochondrial membrane, called
cristae, increase the membrane’s surface area,
enhancing the mitochondrion’s ability to produce
ATP.
© 2016 Pearson Education, Ltd.
- 85. 4.14 Chloroplasts convert solar energy to
chemical energy
• Photosynthesis is the conversion of light energy
from the sun to the chemical energy of sugar
molecules.
• Chloroplasts are the photosynthesizing
organelles of plants and algae.
© 2016 Pearson Education, Ltd.
- 86. 4.14 Chloroplasts convert solar energy to
chemical energy
• Chloroplasts are partitioned into compartments.
• Between the outer and inner membrane is a thin
intermembrane space.
• Inside the inner membrane is a thick fluid called
stroma, which contains the chloroplast DNA,
ribosomes, many enzymes, and a network of
interconnected sacs called thylakoids, where green
chlorophyll molecules trap solar energy.
• In some regions, thylakoids are stacked like poker
chips. Each stack is called a granum.
© 2016 Pearson Education, Ltd.
- 88. 4.15 EVOLUTION CONNECTION:
Mitochondria and chloroplasts evolved by
endosymbiosis
• Mitochondria and chloroplasts contain
• DNA and
• ribosomes.
• The structure of this DNA and these ribosomes is
very similar to that found in prokaryotic cells.
© 2016 Pearson Education, Ltd.
- 89. 4.15 EVOLUTION CONNECTION:
Mitochondria and chloroplasts evolved by
endosymbiosis
• The endosymbiont theory states that
• mitochondria and chloroplasts were formerly small
prokaryotes and
• they began living within larger cells.
© 2016 Pearson Education, Ltd.
- 95. 4.16 The cell’s internal skeleton helps
organize its structure and activities
• Cells contain a network of protein fibers, called the
cytoskeleton, which organize the structures and
activities of the cell.
© 2016 Pearson Education, Ltd.
- 97. 4.16 The cell’s internal skeleton helps
organize its structure and activities
• Microtubules (made of tubulin)
• shape and support the cell and
• act as tracks along which organelles equipped with
motor proteins move.
• In animal cells, microtubules grow out from a
region near the nucleus called the centrosome,
which contains a pair of centrioles, each composed
of a ring of microtubules.
© 2016 Pearson Education, Ltd.
- 98. 4.16 The cell’s internal skeleton helps
organize its structure and activities
• Intermediate filaments
• are found in the cells of most animals,
• reinforce cell shape and anchor some organelles,
and
• are often more permanent fixtures in the cell.
© 2016 Pearson Education, Ltd.
- 99. 4.16 The cell’s internal skeleton helps
organize its structure and activities
• Microfilaments (actin filaments)
• support the cell’s shape and
• are involved in motility.
© 2016 Pearson Education, Ltd.
- 107. 4.17 SCIENTIFIC THINKING: Scientists
discovered the cytoskeleton using the tools
of biochemistry and microscopy
• In the 1940s, biochemists first isolated and
identified the proteins actin and myosin from
muscle cells.
• In 1954, scientists, using newly developed
techniques of microscopy, established how
filaments of actin and myosin interact in muscle
contraction.
• In the next decade, researchers identified actin
filaments in all types of cells.
© 2016 Pearson Education, Ltd.
- 108. 4.17 SCIENTIFIC THINKING: Scientists
discovered the cytoskeleton using the tools
of biochemistry and microscopy
• In the 1970s, scientists were able to visualize actin
filaments using fluorescent tags and in living cells.
• In the 1980s, biologists were able to record the
changing architecture of the cytoskeleton.
© 2016 Pearson Education, Ltd.
- 110. 4.18 Cilia and flagella move when
microtubules bend
• The short, numerous appendages that propel
protists such as Paramecium are called cilia
(singular, cilium).
• Other protists may move using flagella, which are
longer than cilia and usually limited to one or a few
per cell.
• Some cells of multicellular organisms also have
cilia or flagella.
© 2016 Pearson Education, Ltd.
- 115. 4.18 Cilia and flagella move when
microtubules bend
• A flagellum, longer than cilia, propels a cell by an
undulating, whiplike motion.
• Cilia work more like the oars of a boat.
• Although differences exist, flagella and cilia have a
common structure and mechanism of movement.
© 2016 Pearson Education, Ltd.
- 116. 4.18 Cilia and flagella move when
microtubules bend
• Both flagella and cilia are composed of
microtubules wrapped in an extension of the
plasma membrane.
• In nearly all eukaryotic cilia and flagella, a ring of
nine microtubule doublets surrounds a central pair
of microtubules.
• This arrangement is called the 9 2 pattern.
• The microtubule assembly is anchored in a basal
body with nine microtubule triplets arranged in a
ring.
© 2016 Pearson Education, Ltd.
- 121. 4.18 Cilia and flagella move when
microtubules bend
• Cilia and flagella move by bending motor proteins
called dynein feet.
• These feet attach to and exert a sliding force on an
adjacent doublet.
• This “walking” causes the microtubules to bend.
© 2016 Pearson Education, Ltd.
- 122. 4.19 The extracellular matrix of animal cells
functions in support and regulation
• Animal cells synthesize and secrete an elaborate
extracellular matrix (ECM), which
• helps hold cells together in tissues and
• protects and supports the plasma membrane.
© 2016 Pearson Education, Ltd.
- 123. 4.19 The extracellular matrix of animal cells
functions in support and regulation
• The ECM may attach to the cell through other
glycoproteins that then bind to membrane proteins
called integrins.
• Integrins
• span the membrane and
• attach on the other side to proteins connected to
microfilaments of the cytoskeleton.
© 2016 Pearson Education, Ltd.
- 124. Figure 4.19
Collagen fiber
EXTRACELLULAR FLUID
CYTOPLASM
Glycoprotein
complex with long
polysaccharide
Connecting
glycoprotein
Integrin
Plasma
membrane
Microfilaments
of cytoskeleton
© 2016 Pearson Education, Ltd.
- 125. 4.20 Three types of cell junctions are found in
animal tissues
• Adjacent cells adhere, interact, and communicate
through specialized junctions between them.
• Tight junctions prevent leakage of fluid across a
layer of epithelial cells.
• Anchoring junctions fasten cells together into
sheets.
• Gap junctions are channels that allow small
molecules to flow through protein-lined pores
between cells.
© 2016 Pearson Education, Ltd.
- 130. 4.21 Cell walls enclose and support plant
cells
• A plant cell, but not an animal cell, has a rigid cell
wall that
• protects and provides skeletal support that helps
keep the plant upright and
• is primarily composed of cellulose.
• Plant cells have cell junctions called
plasmodesmata that allow plants tissues to share
• water,
• nourishment, and
• chemical messages.
© 2016 Pearson Education, Ltd.
- 132. 4.22 Review: Eukaryotic cell structures can
be grouped on the basis of four main
functions
• Eukaryotic cell structures can be grouped on the
basis of four functions:
1. genetic control,
2. manufacturing, distribution, and breakdown of
materials,
3. energy processing, and
4. structural support, movement, and intercellular
communication.
© 2016 Pearson Education, Ltd.
- 136. You should now be able to
1. Describe the importance of microscopes in
understanding cell structure and function.
2. Describe the two parts of cell theory.
3. Distinguish between the structures of prokaryotic
and eukaryotic cells.
4. Explain how cell size is limited.
5. Describe the structure and functions of cell
membranes.
© 2016 Pearson Education, Ltd.
- 137. You should now be able to
6. Explain why compartmentalization is important in
eukaryotic cells.
7. Compare the structures of plant and animal cells.
Note the function of each cell part.
8. Compare the structures and functions of
chloroplasts and mitochondria.
9. Describe the evidence that suggests that
mitochondria and chloroplasts evolved by
endosymbiosis.
© 2016 Pearson Education, Ltd.
- 138. You should now be able to
10. Compare the structures and functions of
microfilaments, intermediate filaments, and
microtubules.
11. Relate the structure of cilia and flagella to their
functions.
12. Relate the structure of the extracellular matrix to
its functions.
13. Compare the structures and functions of tight
junctions, anchoring junctions, and gap
junctions.
© 2016 Pearson Education, Ltd.
- 139. You should now be able to
14. Relate the structures of plant cell walls and
plasmodesmata to their functions.
15. Describe the four functional categories of
organelles in eukaryotic cells.
© 2016 Pearson Education, Ltd.