Download The Golgi Apparatus

CHAPTER 4
A Tour of the Cell
Figures 4.1 – 4.3
PowerPoint® Lecture Slides for
Essential Biology, Second Edition & Essential Biology with Physiology
Neil Campbell, Jane Reece, and Eric Simon
Presentation prepared by Chris C. Romero
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
• If you stacked up 8000
cell membranes, they
would be only as thick
as a page in this book
• Every second, your
body produces about
2 million red blood
cells
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
• An electron microscope
can visualize objects a
million times smaller
than the head of a pin
• The cells of a whale
are about the same size
as the cells of a mouse
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
BIOLOGY AND SOCIETY:
DRUGS THAT TARGET CELLS
• Antibiotics are one of the great marvels of
modern medicine
– Treatment with
these drugs will
kill invading
bacteria
– The drugs don’t
harm the human
cells of the host
Figure 4.1
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THE MICROSCOPIC WORLD OF CELLS
• Cells are the building blocks of all life
• Cells must be tiny for materials to move in and out
of them fast enough to meet the cell’s metabolic
needs
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• Organisms are either
– Single-celled, such as most bacteria and protists
– Multicelled, such as plants, animals, and most fungi
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Microscopes as Windows to Cells
• The light microscope is used by many scientists
– Light passes
through the
specimen
– Lenses enlarge,
or magnify, the
image
(a) Light micrograph (LM) of a white blood cell
(stained purple) surrounded by red blood cells
Figure 4.2A
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• Magnification
– An increase in the specimen’s apparent size
• Resolving power
– The ability of an optical instrument to show two
objects as separate
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• Cells were first discovered in 1665 by Robert
Hooke
• The accumulation of scientific evidence led to the
cell theory
– All living things are composed of cells
– All cells form from previously existing cells
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• The electron microscope (EM) uses a beam of
electrons
– It has a higher resolving power than the light
microscope
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• The electron
microscope can
magnify up to
100,000X
Human height
Length of some
nerve and
muscle cells
Chicken
egg
Frog
eggs
– Such power
reveals the
diverse parts
within a cell
Plant and
animal
cells
Nucleus
Most bacteria
Mitochondrion
Smallest bacteria
Viruses
Ribosomes
Proteins
Lipids
Small
molecules
Atoms
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Figure 4.3
• The scanning
electron
microscope
(SEM) is used to
study the detailed
architecture of
the surface of a
cell
(b) Scanning electron micrograph (SEM) of a white
blood cell
Figure 4.2B
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• The transmission electron microscope (TEM) is
useful for exploring the internal structure of a cell
(c) Transmission electron micrograph (TEM) of a white blood cell
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Figure 4.2C
The Two Major Categories of Cells
• The countless cells on earth fall into two categories
– Prokaryotic cells
– Eukaryotic cells
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• Prokaryotic and eukaryotic cells differ in several
respects
Prokaryotic cell
Nucleoid region
Eukaryotic cell
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Nucleus
Organelles
Figure 4.4
• Prokaryotic cells
– Are smaller than eukaryotic cells
– Lack internal structures surrounded by membranes
– Lack a nucleus
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Prokaryotic
flagella
Nucleoid region (DNA)
Ribosomes
Plasma
membrane
Cell wall
Capsule
Pili
Figure 4.5
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A Panoramic View of Eukaryotic Cells
• An idealized animal cell
Ribosomes
Cytoskeleton
Centriole
Lysosome
Flagellum
Not in most
plant cells
Plasma
membrane
Nucleus
Mitochondrion
Rough
endoplasmic
reticulum (ER)
Golgi
apparatus
Smooth
endoplasmic
reticulum (ER)
Figure 4.6A
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
• An idealized plant cell
Not in animal cells
Cytoskeleton
Mitochondrion
Central
vacuole
Nucleus
Cell wall
Rough endoplamsic
reticulum (ER)
Chloroplast
Ribosomes
Plasma
membrane
Smooth
endoplasmic
reticulum (ER)
Plasmodesmata
Golgi apparatus
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Figure 4.6B
MEMBRANE STRUCTURE AND FUNCTION
• The plasma membrane separates the living cell from
its nonliving surroundings
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A Fluid Mosaic of Lipids and Proteins
• The membranes of cells are composed of
– Lipids
– Proteins
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• The lipids belong to a special category called
phospholipids
• Phospholipids form a two-layered membrane, the
phospholipid bilayer
Outside cell
Hydrophilic
head
Hydrophobic
tail
Cytoplasm
(inside cell)
(a) Phospholipid bilayer of membrane
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Figure 4.7A
• Most membranes have specific proteins embedded
in the phospholipid bilayer
Hydrophilic
region of
protein
Phospholipid
bilayer
Hydrophobic
region of protein
(b) Fluid mosaic model of membrane
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Figure 4.7B
• Some functions of membrane proteins
Cytoplasm
Fibers of
extracellular
matrix
c Enzymatic activity
b Cell signaling
a Attachment to
cytoskeleton and
extracellular
matrix
e Intercellular
joining
d Transport
Cytoskeleton
f Cell-cell
recognition
Cytoplasm
Figure 4.8
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
• Membrane phospholipids and proteins can drift
about in the plane of the membrane
• This behavior leads to the description of a
membrane as a fluid mosaic
– Molecules can move freely within the membrane
– A diversity of proteins exists within the membrane
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Selective Permeability
• Membranes of the cell are selectively permeable
– They allow some substances to cross more easily
than others
– They block passage of some substances altogether
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• The traffic of some substances can only occur
through transport proteins
– Glucose, for example, requires a transport protein to
move it into the cell
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THE NUCLEUS AND RIBOSOMES:
GENETIC CONTROL OF THE CELL
• The nucleus is the manager of the cell
– Genes in the nucleus store information necessary to
produce proteins
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Structure and Function of the Nucleus
• The nucleus is bordered by a double membrane
called the nuclear envelope
– It contains chromatin
– It contains a nucleolus
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Ribosomes
Chromatic
Nuclear
envelope
Nucleolus
Pore
Figure 4.9
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Ribosomes
• Ribosomes build all the cell’s proteins
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How DNA Controls the Cell
• DNA controls the cell
by transferring its
coded information
into RNA
– The information in
the RNA is used to
make proteins
DNA
1 Synthesis of
mRNA in the
nucleus
Nucleus
Cytoplasm
2 Movement of
mRNA into
cytoplasm via
nuclear pore
3 Synthesis of
protein in the
cytoplasm
Figure 4.10
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mRNA
mRNA
Ribosome
Protein
THE ENDOMEMBRANE SYSTEM:
MANUFACTURING AND DISTRIBUTING
CELLULAR PRODUCTS
• Many of the membranous organelles in the cell
belong to the endomembrane system
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The Endoplasmic Reticulum
• The endoplasmic
reticulum (ER)
Nuclear
envelope
– Produces an
enormous variety
of molecules
– Is composed of
smooth and rough
ER
Ribosomes
Rough ER
Smooth ER
Figure 4.11
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
Rough ER
• The “roughness” of the rough ER is due to
ribosomes that stud the outside of the ER
membrane
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
• The functions of the rough ER include
– Producing proteins
– Producing new membrane
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
• After the rough ER synthesizes a molecule it
packages the molecule into transport vesicles
4
Transport vesicle
buds off
Ribosome
3
Secretory
protein inside
transport
vesicle
Protein
1
2
Rough ER
Polypeptide
Figure 4.12
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
Smooth ER
• The smooth ER lacks the surface ribosomes of ER
and produces lipids, including steroids
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
The Golgi Apparatus
• The Golgi apparatus
– Works in partnership with the ER
– Refines, stores, and distributes the products of cells
Transport
vesicle
from ER
“Receiving” side of
Golgi apparatus
Golgi apparatus
New vesicle forming
Transport vesicle
from the Golgi
“Shipping” side of
Golgi apparatus
Plasma membrane
Figure 4.13
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Lysosomes
• A lysosome is a membrane-enclosed sac
– It contains digestive enzymes
– The enzymes break down macromolecules
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• Lysosomes have several types of digestive functions
– They fuse with food vacuoles to digest the food
Lysosome
Digestive enzymes
Plasma
membrane
Digestion
Food
Food vacuole
(a) Lysosome digesting food
Figure 4.14a
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– They break down damaged organelles
Lysosome
Digestion
Damaged
organelle
(b) Lysosome breaking down damaged organelle
Figure 4.14b
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
Vacuoles
• Vacuoles are membranous sacs
– Two types are the contractile vacuoles of protists and
the central vacuoles of plants
Central
vacuole
Contractile
vacuoles
(a) Contractile vacuoles in a protist
(b) Central vacuole in a plant cell
Figure 4.15
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
• A review of the
endomembrane
system
Rough ER
Transport
vesicle from ER
Golgi
apparatus
Secretory
vesicle from Golgi
Secretory
protein
Vacuole
Plasma membrane
Figure 4.16
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
Lysosome
CHAPTER 4
A Tour of the Cell
Figures 4.17 – 4.23
PowerPoint® Lecture Slides for
Essential Biology, Second Edition & Essential Biology with Physiology
Neil Campbell, Jane Reece, and Eric Simon
Presentation prepared by Chris C. Romero
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
CHLOROPLASTS AND MITOCHONDRIA:
ENERGY CONVERSION
• Cells require a constant energy supply to do all the
work of life
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CHLOROPLASTS
• Chloroplasts are
the sites of
photosynthesis,
the conversion of
light energy to
chemical energy
Figure 4.17
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
Inner and outer
membranes of
envelope
Granum
Space between
membranes
Stroma (fluid in
chloroplast)
Mitochondria
• Mitochondria are the sites of cellular respiration,
which involves the production of ATP from food
molecules
Outer
membrane
Inner
membrane
Cristae
Matrix
Space between
membranes
Figure 4.18
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
THE CYTOSKELETON:
CELL SHAPE AND MOVEMENT
• The cytoskeleton is an infrastructure of the cell
consisting of a network of fibers
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Maintaining Cell Shape
• One function of
the cytoskeleton
– Provide
mechanical
support to the
cell and
maintain its
shape
Figure 4.19A
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
• The cytoskeleton can
change the shape of a cell
– This allows cells like
amoebae to move
Figure 4.19B
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
Cilia and Flagella
• Cilia and flagella are motile appendages
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• Flagella propel the cell
in a whiplike motion
• Cilia move in a
coordinated back-andforth motion
Figure 4.20A, B
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• Some cilia or flagella
extend from nonmoving
cells
– The human windpipe is
lined with cilia
Figure 4.20C
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CELL SURFACES:
PROTECTION, SUPPORT, AND CELL-CELL
INTERACTIONS
• Most cells secrete materials that are external to the
plasma membrane
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Plant Cell Walls and Cell Junctions
• Plant cells are encased by cell walls
– These provide support for the plant cells
Walls of two adjacent
plant cells
Vacuole
Plasmodesmata
(channels between cells)
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Figure 4.21
Animal Cell Surfaces and Cell Junctions
• Animal cells lack cell walls
– They secrete a sticky covering called the extracellular
matrix
– This layer helps hold cells together
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• Animal cells connect by various types of junctions
– Tight junctions
– Adhering junctions
– Communicating junctions
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
Extracellular matrix
(a) Tight junctions
(b) Anchoring
junctions
(c) Communicating
junctions
Plasma membranes
of adjacent cells
Extracellular matrix
Figure 4.22
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EVOLUTION CONNECTION:
THE ORIGIN OF MEMBRANES
• Phospholipids were probably among the organic
molecules on the early Earth
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• When mixed
with water,
phospholipids
spontaneously
form
membranes
Figure 4.23
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SUMMARY OF KEY CONCEPTS
• The Two Major Categories of Cells
Visual Summary 4.1
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Membrane Structure and Function
• A Fluid Mosaic of Lipids and Proteins
Outside cell
Phospholipid
Hydrophilic
Protein
Hydrophobic
Hydrophilic
Cytoplasm (inside cell)
Visual Summary 4.2
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings