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BIOLOGY
CONCEPTS & CONNECTIONS
Fourth Edition
Neil A. Campbell • Jane B. Reece • Lawrence G. Mitchell • Martha R. Taylor
CHAPTER 4
A Tour of the Cell
Modules 4.1 – 4.5
From PowerPoint® Lectures for Biology: Concepts & Connections
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Prokaryotic cells are small and structurally simple
• prokaryotic and eukaryotic
• Prokaryotic cells: small, no nucleus or
membrane bound organelles
• Eukaryotic cells: nucleus, membrane bound
organelles
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• A prokaryotic cell = bacteria
– cell wall =
peptidoglycan
Prokaryotic
flagella
Ribosomes
Capsule
Cell wall
Plasma
membrane
Pili
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Nucleoid region
(DNA)
Figure 4.4
• An animal cell
Smooth
endoplasmic
reticulum
Nucleus
Rough
endoplasmic
reticulum
Flagellum
Not in most
plant cells
Lysosome
Centriole
Ribosomes
Peroxisome
Microtubule
Cytoskeleton
Intermediate
filament
Microfilament
Figure 4.5A
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Golgi
apparatus
Plasma membrane
Mitochondrion
• A plant cell
– Chloroplasts
– A rigid cell wall
– Large Central Vacuoule
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Nucleus
Rough
endoplasmic
reticulum
Ribosomes
Smooth
endoplasmic
reticulum
Golgi
apparatus
Microtubule
Not in
animal
cells
Central
vacuole
Intermediate
filament
Chloroplast
Microfilament
Cell wall
Mitochondrion
Peroxisome
Plasma membrane
Figure 4.5B
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Cytoskeleton
MEMBRANE STRUCTURE AND FUNCTION
Membranes organize the chemical activities of cells
• Membranes: site of chemical reaction and
transport


Cytoplasm
Figure 5.10
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• Membranes = selectively permeable
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Membrane phospholipids form a bilayer
• Phospholipids
hydrophilic head
(phosphate –
polar) and two
hydrophobic tails
(nonpolar fatty
acid)
Head
Symbol
Tails
Figure 5.11A
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• In water, phospholipids form bilayer
– heads outward and tails inward
Water
Hydrophilic
heads
Hydrophobic
tails
Water
Figure 5.11B
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The membrane is a fluid mosaic of phospholipids
and proteins
• Phospholipid molecules form a flexible bilayer
– Cholesterol = keep flexible in body temperature
– Carbohydrates = cell identification tags
– Proteins =
- enzymes
- transport proteins
- receptors
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• The plasma membrane of an animal cell
Glycoprotein
Carbohydrate
(of
glycoprotein)
Fibers of the
extracellular
matrix
Glycolipid
Phospholipid
Cholesterol
Microfilaments
of the
cytoskeleton
Proteins
CYTOPLASM
Figure 5.12
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• 3 types cell membrane proteins
Messenger molecule
Receptor
Activated
molecule
Figure 5.13
Enzyme activity
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Signal transduction
ACTIVE vs PASSIVE Transport
• Passive Transport
- high to low concentration (No Energy needed)
• Active Transport
– Low to high concentration (Energy needed)
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Passive transport is diffusion across a membrane
• PASSIVE
TRANSPORT
Molecule
of dye
Membrane
EQUILIBRIUM
• Ex diffusion
EQUILIBRIUM
Figure 5.14A & B
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Osmosis is the passive transport of water
• Passive Transport:
Osmosis: water hi
to lo
• Solute dissolves in
solvent
• Ex. Salt water =
salt (solute) and
water (solution)
Hypotonic
solution
Hypertonic
solution
Selectively
permeable
membrane
Solute
molecule
HYPOTONIC SOLUTION
HYPERTONIC SOLUTION
Water
molecule
Selectively
permeable
membrane
Solute molecule with
cluster of water molecules
NET FLOW OF WATER
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Figure 5.15
Amount vs Concentration
• Concentration: RATIO of solute to Solvent
- Hypertonic – more concentration (more
solute to solvent)
- Hypotonic – less concentration (less solute to
solvent)
- Isotonic – same concentration
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Water balance between cells and their surroundings
is crucial to organisms
• Osmoregulation
• Isotonic solution – cell stays same
• Hypertonic solution – cell shrivels
• Hypotonic solution – cell bursts (less so with
plants)
ISOTONIC
SOLUTION
HYPOTONIC
SOLUTION
HYPERTONIC
SOLUTION
(1) Normal
(2) Lysing
(3) Shriveled
ANIMAL
CELL
Plasma
membrane
PLANT
CELL
Figure 5.16
(4) Flaccid
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(5) Turgid
(6) Shriveled
Transport proteins facilitate diffusion across
membranes
• Small nonpolar molecules diffuse freely through
the phospholipid bilayer
• Many other kinds of molecules pass through
selective protein pores by facilitated diffusion
Solute
molecule
Transport
protein
Figure 5.17
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Cells expend energy for active transport
• Transport proteins can move solutes across a
membrane against a concentration gradient
– active transport
– Active transport requires ATP
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• Active
transport in
two solutes
across a
membrane
FLUID
OUTSIDE
CELL
Phosphorylated
transport protein
Transport
protein
First
solute
1
First solute,
inside cell,
binds to protein
2
ATP transfers
phosphate to
protein
3
Protein releases
solute outside
cell
5
Phosphate
detaches from
protein
6
Protein releases
second solute
into cell
Second
solute
4
Second solute
binds to protein
Figure 5.18
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Exocytosis and endocytosis transport large
molecules
• Exocytosis
FLUID OUTSIDE CELL
Figure 5.19A
CYTOPLASM
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– (endocytosis)
Figure 5.19B
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• Three kinds of endocytosis
Pseudopod of
amoeba
Food being
ingested
Plasma
membrane
Material bound to
receptor proteins
PIT
Cytoplasm
Figure 5.19C
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Eukaryotic organelles comprise four functional
categories
• Eukaryotic organelles fall into four functional
groups
Table 4.20
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Table 4.20 (continued)
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PROTEIN SYNTHESIS ORGANELLES
The nucleus is the cell’s genetic control center
• Nucleus – DNA (protein blueprint)
• nucleus separated by nuclear envelope
• Rough ER – endoplasmic reticulum has
ribosomes
• Ribosomes – makes protein
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NUCLEUS
Chromatin
Nucleolus
Two membranes
of nuclear
envelope
Pore
ROUGH
ENDOPLASMIC
RETICULUM
Ribosomes
Figure 4.6
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Rough endoplasmic reticulum makes membrane
and proteins
• rough ER makes membranes
• Ribosomes - proteins
Transport vesicle
buds off
4
Ribosome
Sugar
chain
1
Figure 4.8
3
Secretory
(glyco-) protein
inside transport
vesicle
Glycoprotein
2
Polypeptide
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ROUGH ER
Smooth endoplasmic reticulum has a variety of
functions
• Smooth ER = makes lipids
• sometimes regulates carbohydrate metabolism
and breaks down toxins and drugs
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SMOOTH ER
ROUGH
ER
Nuclear
envelope
Ribosomes
SMOOTH ER
Figure 4.9
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ROUGH ER
The Golgi apparatus finishes, sorts, and ships cell
products
• Golgi apparatus = modifies proteins and sends
to other part of cell or out
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• The Golgi apparatus
Golgi apparatus
Golgi
apparatus
“Receiving” side of
Golgi apparatus
Transport
vesicle
from ER
New
vesicle
forming
“Shipping”
side of Golgi
apparatus
Transport vesicle
from the Golgi
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Figure 4.10
Lysosomes digest the cell’s food and wastes
• Lysosomes –
sacs with
digestive
enzymes budded
off the Golgi
LYSOSOME
Nucleus
Figure 4.11A
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• Lysosomal enzymes
– digest food
– destroy bacteria
– recycle damaged organelles
– function in embryonic development in animals
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Rough ER
Transport vesicle
(containing inactive
hydrolytic enzymes)
Plasma
membrane
Golgi
apparatus
Engulfment
of particle
Lysosome
engulfing
damaged
organelle
“Food”
LYSOSOMES
Food
vacuole
Figure 4.11B
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Digestion
Vacuoles function in the general maintenance of the
cell
• Plant - large
central vacuole
– The vacuole has
lysosomal and
storage
functions
Central
vacuole
Nucleus
Figure 4.13A
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• Protists may have contractile vacuoles
– These pump out excess water
Nucleus
Contractile
vacuoles
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Figure 4.13B
A review of the protein synthesis organelles
Rough
ER
Transport
vesicle
from Golgi
Transport
vesicle
from ER
Plasma
membrane
Vacuole
Nucleus
Lysosome
Smooth
ER
Nuclear
envelope
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Golgi
apparatus
Figure 4.14
ENERGY PROCESSING: Chloroplasts and
mitochondria
• Chloroplasts – photosynthesis
• Mitochondria – breakdown sugar to make ATP
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MITOCHONDRION
Outer
membrane
Intermembrane
space
Inner
membrane
Cristae
Figure 4.16
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Matrix
THE CYTOSKELETON AND RELATED
STRUCTURES
The cell’s internal skeleton helps organize its
structure and activities
• A network of protein fibers makes up the
cytoskeleton
Figure 4.17A
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• Microfilaments - enable cells to change shape
and move
• Intermediate filaments - reinforce the cell and
anchor certain organelles
• Microtubules
– give the cell rigidity
– provide anchors for organelles
– act as tracks for organelle movement
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Cilia and flagella move when microtubules bend
• Eukaryotic cilia and flagella help to move
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