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Chapter 4
A Tour of the Cell
PowerPoint Lectures for
Biology: Concepts and Connections, Fifth Edition
– Campbell, Reece, Taylor, and Simon
Lectures by Chris Romero
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
The Art of Looking at Cells
• Early scientists who observed cells
– Made detailed sketches of what they saw
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• These early sketches revealed an important
relationship
– Between art and biology, the most visual of the
sciences
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
INTRODUCTION TO THE CELL
4.1 Microscopes provide windows to the world of the cell
• The light microscope (LM)
– Enables us to see the overall shape and structure
of a cell
Eyepiece
Ocular
lens
Objective lens
Specimen
Condenser
lens
Light
source
Figure 4.1A
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• Light microscopes
Figure 4.1B
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LM 1,000
– Magnify cells, living and preserved, up to
1,000 times
• The electron microscope
Figure 4.1C
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TEM 2,800 
SEM 2,000 
– Allows greater magnification and reveals
cellular details
Figure 4.1D
• Different types of light microscopes
220
1,000
– Use different techniques to enhance contrast
and selectively highlight cellular components
Figure 4.1E
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Figure 4.1F
4.2 Most cells are microscopic
• Cells vary in size and shape
10 m
100 mm
(10 cm)
Length of some
nerve and
muscle cells
Chicken egg
Unaided eye
Human height
1m
10 mm
(1 cm)
Frog egg
100 m
Most plant and
animal cells
10 m
Nucleus
Light microscope
1 mm
Most bacteria
100 nm
Mitochondrion
Mycoplasmas
(smallest bacteria)
Viruses
Ribosome
10 nm
Proteins
Lipids
1 nm
Small molecules
Figure 4.2A
0.1 nm
Atoms
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Electron microscope
1 m
• The microscopic size of most cells ensures a
sufficient surface area
– Across which nutrients and wastes can
move to service the cell volume
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• A small cell has a greater ratio of surface area
to volume
– Than a large cell of the same shape
10 m
30 m
30 m
Figure 4.2B
Surface area
of one large cube
 5,400 m2
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10 m
Total surface area
of 27 small cubes
 16,200 m2
4.3 Prokaryotic cells are structurally simpler than
eukaryotic cells
• There are two kinds of cells
Colorized TEM 15,000 
– Prokaryotic and eukaryotic
Prokaryotic cell
Nucleoid
region
Nucleus
Figure 4.3A
Eukaryotic cell
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Organelles
• Prokaryotic cells are small, relatively simple cells
– That do not have a membrane-bound nucleus
Prokaryotic
flagella
Ribosomes
Capsule
Cell wall
Plasma
membrane
Nucleoid region (DNA)
Pili
Figure 4.3B
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4.4 Eukaryotic cells are partitioned into functional
compartments
• All other forms of life are composed of more
complex eukaryotic cells
– Distinguished by the presence of a true
nucleus
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• Membranes form the boundaries of many
eukaryotic cells
– Compartmentalizing the interior of the cell
and facilitating a variety of metabolic
activities
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• A typical animal cell
– Contains a variety of membranous organelles
Smooth endoplasmic
reticulum
Nucleus
Rough
endoplasmic
reticulum
Flagellum
Not in most
plant cells
Lysosome
Ribosomes
Centriole
Peroxisome
Microtubule
Cytoskeleton
Golgi
apparatus
Plasma membrane
Intermediate
filament
Mitochondrion
Figure 4.4A
Microfilament
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• A typical plant cells- chloroplasts & cell wall
Nucleus
Rough
endoplasmic
reticulum
Ribosomes
Smooth
endoplasmic
reticulum
Golgi
apparatus
Microtubule
Not in
animal
cells
Central
vacuole
Chloroplast
Cell wall
Mitochondrion
Peroxisome
Plasma membrane
Figure 4.4B
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Intermediate
filament
Microfilament
Cytoskeleton
ORGANELLES OF THE ENDOMEMBRANE SYSTEM
Flow of Information in the Cell
Nuclear Pores
DNA
Protein
RNA
Rough ER
ribosomes
Nucleus
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ribosomes to
Golgi Apparatus
Cytoplasm
• The nucleus is the cellular control center
– Containing the cell’s DNA, which directs
cellular activities
Chromatin
Nucleus
Nucleolus
Two membranes
of nuclear
envelope
Pore
Rough
endoplasmic
reticulum
Figure 4.5
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Ribosomes
Organelles are
connected through the
Endomembrane
system
The endomembrane
system is
membranous
organelles with
interchangeable
membranes
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Endomembrane System
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4.7 Smooth endoplasmic reticulum has a variety of functions
• Smooth endoplasmic reticulum, or smooth ER
– Synthesizes lipids
– Processes toxins and drugs in liver cells
– Stores and releases calcium ions in muscle cells
Smooth ER
Rough ER
Nuclear
envelope
Figure 4.7
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Ribosomes
Rough ER
TEM 45,000
Smooth ER
4.8 Rough endoplasmic reticulum makes
membrane and proteins
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Endomembrane System
Can you identify all the pieces of endomembrane system?
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• Ribosomes on the surface of the rough ER
– Produce proteins that are secreted,
inserted into membranes, or transported in
vesicles to other organelles
Transport vesicle
buds off
4
Ribosome
3
Secretory
(glyco-) protein
inside transport vesicle
Sugar chain
1
2
Glycoprotein
Polypeptide
Rough ER
Figure 4.8
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4.9 The Golgi apparatus finishes, sorts, and ships
cell products
• Stacks of membranous sacs receive and modify
ER products
– Then ship them to other organelles or the cell
surface
Golgi apparatus
Golgi
apparatus
Transport
vesicle
from ER
New vesicle
forming
Figure 4.9
“Shipping” side
of Golgi apparatus
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Transport
vesicle from
the Golgi
TEM 130,000
“Receiving” side of
Golgi apparatus
4.10 Lysosomes are digestive compartments
within a cell
• Lysosomes are sacs of enzymes
– That function in digestion within a cell
Rough ER
1
Transport vesicle
(containing inactive
hydrolytic enzymes)
Golgi
apparatus
Plasma
membrane
Engulfment
of particle
Lysosome
engulfing
damaged
organelle
2
“Food”
Lysosomes
3
5
Food
vacuole
Figure 4.10A
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4
Digestion
• Lysosomes in white blood cells
– Destroy bacteria that have been ingested
Lysosome
Figure 4.10B
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TEM 8,500
Nucleus
• Lysosomes also recycle damaged organelles
Lysosome containing
two damaged organelles
Peroxisome fragment
Figure 4.10C
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TEM 42,500
Mitochondrion fragment
`
Tay Sachs- Lysosomal Storage Disorder
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4.12 Vacuoles function in the general
maintenance of the cell
• Plant cells contain a large central vacuole,
– Which has lysosomal and storage functions
Nucleus
Chloroplast
Figure 4.12A
Colorized TEM 8,700
Central
vacuole
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• Some protists have contractile vacuoles
– That pump out excess water
Contractile
vacuoles
Figure 4.12B
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LM 650
Nucleus
4.13 A review of the endomembrane system
• The various organelles of the endomembrane system
– Are interconnected structurally and functionally
Rough ER
Transport vesicle
from ER to Golgi
Transport vesicle from
Golgi to plasma membrane
Plasma
membrane
Nucleus
Vacuole
Lysosome
Figure 4.13
Smooth ER
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Nuclear envelope
Golgi apparatus
ENERGY-CONVERTING ORGANELLES
4.14 Chloroplasts convert solar energy to chemical
energy
• Chloroplasts, found in plants and some protists
– Convert solar energy to chemical energy in
sugars
Chloroplast
Inner and outer
membranes
Granum
Intermembrane
space
Figure 4.14
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TEM 9,750
Stroma
4.15 Mitochondria harvest chemical energy from food
• Mitochondria carry out cellular respiration
– Which uses the chemical energy in food to
make ATP for cellular work
Mitochondrion
Outer
membrane
Inner
membrane
Cristae
Figure 4.15
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Matrix
TEM 44,880
Intermembrane
space
THE CYTOSKELETON AND RELATED STRUCTURES
4.16 The cell’s internal skeleton helps organize
its structure and activities
• A network of protein fibers
– Make up the cytoskeleton.
Tubulin subunit
Actin subunit
Fibrous subunits
7 nm
Microfilament
Figure 4.16
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25 nm
10 nm
Intermediate filament
Microtubule
• Microfilaments of actin
– Enable cells to change shape and move
• Intermediate filaments
– Reinforce the cell and anchor certain
organelles
• Microtubules give the cell rigidity
– And provide anchors for organelles and act
as tracks for organelle movement
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4.17 Cilia and flagella move when microtubules bend
• Eukaryotic cilia and flagella
Figure 4.17A
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LM 600
Colorized SEM 4,100
– Are locomotor appendages that protrude from
certain cells
Figure 4.17B
• Clusters of microtubules
– Drive the whipping action of these organelles
Flagellum
Electron micrographs
of cross sections:
Outer microtubule
doublet
TEM 206,500
Central
microtubules
Radial spoke
Dynein arms
Flagellum
Figure 4.17C
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Basal body
(structurally identical to
centriole)
TEM 206,500
Plasma
membrane
Basal body
CELL SURFACES AND JUNCTIONS
4.19 Cell surfaces protect, support, and join cells
• Cells interact with their environments and each
other via their surfaces.
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• Plant cells
– Are supported by rigid cell walls made largely
of cellulose
– Connect by plasmodesmata, which are
connecting channels
Walls of two
adjacent plant
cells
Vacuole
Plasmodesmata
Layers of one
plant cell wall
Cytoplasm
Plasma membrane
Figure 4.18A
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• Animal cells are embedded in an extracellular
matrix
– Which binds cells together in tissues
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• Tight junctions can bind cells together into
leakproof sheets
• Anchoring junctions link animal cells into strong
tissues
• Gap junctions allow substances to flow from cell to
cell
Tight junctions
Anchoring junction
Gap junctions
Figure 4.18B
Extracellular matrix
Space between cells
Plasma membranes of adjacent cells
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FUNCTIONAL CATEGORIES OF ORGANELLES
4.19 Eukaryotic organelles comprise four
functional categories
• Eukaryotic organelles fall into four functional
groups
– Manufacturing
– Breakdown
– Energy processing
– Support, movement, and communication
between cells
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• Eukaryotic organelles and their functions
Table 4.19
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