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CAMPBELL BIOLOGY IN FOCUS
Urry • Cain • Wasserman • Minorsky • Jackson • Reece

4
A Tour of
the Cell

Lecture Presentations by
Kathleen Fitzpatrick and Nicole Tunbridge
© 2014 Pearson Education, Inc
...


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1: Biologists use microscopes and the
tools of biochemistry to study cells
§  Most cells are too small to be seen by the unaided
eye

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1 m

Human height
Length of some
nerve and
muscle cells
Chicken egg

1 cm

100 µm
10 µm
1 µm
100 nm
10 nm
1 nm
0
...
2

Smallest bacteria
Viruses
Ribosomes

Superresolution
microscopy

Proteins
Lipids
Small molecules
Atoms

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2: Eukaryotic cells have internal
membranes that compartmentalize their functions
§  There are 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

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2

Figure 4
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5 µm
(b) A thin section through
the bacterium Bacillus
coagulans (TEM)

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§  The plasma membrane is a selective barrier
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3

Figure 4
...
1 µm

Carbohydrate side chains

Hydrophilic
region

Hydrophobic
region
Hydrophilic
region

Phospholipid

Proteins

(b) Structure of the plasma membrane
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Figure 4
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4

Figure 4
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Concept 4
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The Nucleus: Information Central
§  The nucleus contains most of the cell’s genes
§  The nuclear membrane is a double membrane;
each membrane consists of a lipid bilayer
§  Pores regulate the entry and exit of molecules
from the nucleus

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Ribosomes: Protein Factories
§  Ribosomes are complexes of ribosomal RNA
and protein

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4: The endomembrane system
regulates protein traffic and performs metabolic
functions in the cell
§  Components of the endomembrane system
§  Endoplasmic reticulum (ER)
§  Golgi apparatus
§  Lysosomes
§  Vacuoles
§  Plasma membrane

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Figure 4
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2 µm

Nuclear
envelope

ER lumen
Cisternae
Ribosomes
Transport vesicle

Transitional
ER

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Functions of Rough ER
§  The rough ER
§  Secrete glycoproteins (proteins covalently
bonded to carbohydrates)
§  Distributes transport vesicles, proteins
surrounded by membranes
§  Is a membrane factory for the cell

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15-1

Nucleus

Rough ER
Smooth ER

Plasma
membrane
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Figure 4
...
1 µm
cis face
(“receiving” side of
Golgi apparatus)

Cisternae

trans face
(“shipping”
side of Golgi
apparatus)

TEM of Golgi apparatus

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15-2

Nucleus

Rough ER
Smooth ER
cis Golgi

trans Golgi

Plasma
membrane

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Vacuoles: Diverse Maintenance Compartments
§  Vacuoles are large vesicles derived from the
ER and Golgi apparatus
§  Some types of cell can engulf another cell by
phagocytosis forming a food vacuole
§  A lysosome fuses with the food vacuole and
digests the molecules

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12

Nucleus

1 µm

Lysosome
Digestive
enzymes
Lysosome
Plasma
membrane

Digestion
Food vacuole

Lysosomes: Phagocytosis
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Figure 4
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Concept 4
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11

Figure 4
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1 µm

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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

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12

Figure 4
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Concept 4
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10 µm

Figure 4
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13

Roles of the Cytoskeleton: Support and Motility
§  The cytoskeleton helps to support the cell and
maintain its shape
§  Inside the cell, vesicles and other organelles can
“walk” along the tracks provided by the cytoskeleton
using motor proteins

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21

ATP

Vesicle
Receptor for
motor protein

Motor protein Microtubule
(ATP powered) of cytoskeleton
(a)  Motor proteins “walk” vesicles along cytoskeletal
fibers
...
25 µm

(b) SEM of a squid giant axon
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14

Components of the Cytoskeleton
§  Three main types of fibers make up the
cytoskeleton
§  Microtubules, microfilaments also called actin
filaments, and intermediate filaments
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Table 4
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Table 4
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15

Table 4
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Centrosomes and Centrioles
§  In animal cells, microtubules grow out from a
centrosome near the nucleus
§  The centrosome is a “microtubule-organizing
center”and it has a pair of centrioles
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Figure 4
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16

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

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23

Outer microtubule
doublet

0
...
1 µm

0
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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

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25

Secondary
cell wall
Primary
cell wall
Middle
lamella

1 µm
Central vacuole
Cytosol
Plasma membrane
Plant cell walls

Plasmodesmata
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The Extracellular Matrix (ECM) of Animal Cells
§  Animal cells lack cell walls but are covered by
an elaborate extracellular matrix (ECM)
§  It is made up of glycoproteins such as collagen,
proteoglycans, and fibronectin

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26a

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