Download Modules04-15to04-21

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 4.15 – 4.21
From PowerPoint® Lectures for Biology: Concepts & Connections
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
ENERGY-CONVERTING ORGANELLES
4.15 Chloroplasts convert solar energy to chemical
energy
• Chloroplasts are found in plants and some protists
• Chloroplasts convert solar energy to chemical energy in
sugars
• Capturing of light and electron enregizing occur in the
grana and chemical reactions forming food storage
molecules occur in the stroma.
Chloroplast
Stroma
Inner and outer
membranes
Granum
Figure 4.15
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Intermembrane
space
4.16 Mitochondria harvest chemical energy from
food
• Mitochondria carry out cellular respiration
– This process uses the chemical energy in food to
make ATP for cellular work
– ATP is the energy storage molecule.
– Cellular respiration takes place in the presence
of oxygen.
– Carbon dioxide and water are given off by the
cell during the oxidation of glucose.
– ATP is produced for the cells energy needs
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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
4.17 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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Actin subunit
Tubulin
subunit
Fibrous subunits
25 nm
7 nm
MICROFILAMENT
10 nm
INTERMEDIATE
FILAMENT
Figure 4.17B
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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
– provide anchors for organelles
– act as tracks for organelle movement
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• A microfilament of actin is a globular structural protein that
polymerizes in a helical fashion . These form the cytoskeleton a three-dimensional network inside an eukaryotic cell. Actin
filaments provide mechanical support for the cell, determine
the cell shape, enable cell movements (through lamellipodia,
filopodia, or pseudopodia); and participate in certain cell
junctions, in cytoplasmic streaming and in contraction of the
cell during cytokinesis..
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• The microfilaments are the thinnest component of the
cytoskeleton, measuring only 5 nm in diameter.
• Actin is one of the most abundant proteins in many
eukaryotic cells, with concentrations of over 100 μM. It is
also one of the most highly conserved proteins, differing by
no more than 5% in species as diverse as algae and
humans.
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• Intermediate filaments (IFs) are cytoskeletal structures
formed by members of a family of related proteins.
Intermediate filaments have a diameter between that of
actin (microfilaments) and microtubules. Most types of
intermediate filaments are located in the cytosol between
the nuclear envelope and the cell surface membrane.
Nuclear lamins are localized to the cell nucleus.
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There are about 70 different genes coding for
various intermediate filament proteins.
However, different kinds of IFs share basic
characteristics: they are all polymers that
generally measure between 9-11 nm in diameter
when fully assembled
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• Microtubules are protein structures found within cells,
one of the components of the cytoskeleton. They have
diameter of ~ 24 nm and length varying from several
micrometers to possibly millimeters in axons of nerve cells.
Microtubules serve as structural components within cells
and are involved in many cellular processes including
mitosis, cytokinesis, and vesicular transport. Microtubules
are polymers of α- and β-tubulin dimers
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4.18 Cilia and flagella move when microtubules
bend
• Eukaryotic cilia and flagella are locomotor
appendages that protrude from certain cells
• A cilia or flagellum is composed of a core of
microtubules wrapped in an extension of the
plasma membrane
• These structures are often associated with many
mitochondria.
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FLAGELLUM
Electron micrograph
of sections:
Outer microtubule
doublet
Plasma
membrane
Flagellum
Central
microtubules
Outer microtubule
doublet
Plasma
membrane
Figure 4.18A
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Basal body
Basal body
(structurally identical to centriole)
• Clusters of microtubules drive the whipping
action of these organelles
Microtubule doublet
Dynein arm
Figure 4.18B
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Sliding
force
EUKARYOTIC CELL SURFACES AND
JUNCTIONS
4.19 Cell surfaces protect, support, and join cells
• Cells interact with their environments and each
other via their surfaces
• Plant cells are supported by rigid cell walls
made largely of cellulose
– They connect by plasmodesmata, channels that
allow them to share water, food, and chemical
messages
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Walls of two
adjacent
plant cells
Vacuole
PLASMODESMATA
Layers of one
plant cell wall
Cytoplasm
Plasma membrane
Figure 4.19A
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• Animal cells are embedded in an extracellular
matrix of predominantly collagens.
– It is a sticky layer of glycoproteins
– It binds cells together in tissues like the mortar of a
brick wall.
– It can also provide a way of separating the tissues, and
regulating intercellular communication
– It can also have protective functions
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• Tight junctions can bind cells together into
leakproof sheets. For this reason they are more
superficial.
• Anchoring
junctions link
animal cells
TIGHT
JUNCTION
ANCHORING
JUNCTION
• Communicating
junctions allow
substances to
flow from cell
to cell
COMMUNICATING
JUNCTION
Plasma
membranes of
adjacent cells
Figure 4.19B
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Extracellular
matrix
4.20 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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Cell types and Their Morphology
• At all levels of organization, biological
structures are shaped by natural selection to
maximize their ability to perform their
functions.
• Many cells have a structure that suits their
function in the body.
• There are about 210 different cell types in the
human body.
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The eye
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The rods and cones of the retina
SEM or TEM?
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Columnar Epithelium such as
that found in the intestine.
> Surface area
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The Nerve Cell
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Muscle cell
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BLOOD Cells
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2-4 pages …. Due December 14th or 15th
• Choose one organelle or cellular body and
discuss a disease which results if that structure
is not functioning properly.
• OR
• Choose a cell type and explain how its structure
is suited for its function.
• References needed
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings