Chapter 6
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
INTRODUCTION TO THE CELL
6.1 Microscopes provide windows to the world of the cell
• The light microscope (LM)
– see the overall shape and structure of a cell
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
Scanning EM (SEM)
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TEM 2,800 
SEM 2,000 
– Allows greater magnification and reveals
cellular details
Figure 4.1D
Transmission EM (TEM)
Cells vary in size and shape
According to the chart:
1. What type of microscope do
you need to view most bacteria?
2. What is highest resolving
power of the electron
microscope?
3. What is the smallest cell you
can see with the unaided eye?
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Cell Fractionation
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Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
1 square inch ~15 grams
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Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Cell Fractionation:
Step 1: Isolate tissue
Step 2: Homogenate
Step 3: Serial Centrifugation
Why?
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6.2 Prokaryotic cells vs. Eukaryotic cells
Figure 4.3A
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• Prokaryotic cells:
• Small
• relatively simple cells
• NO membrane-bound nucleus
• 1 membrane-bound organelle
Figure 4.3B
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Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Eukaryotic cells:
• More complex
• Presence of a true nucleus
• Membranous compartments metabolic
activities
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Typical Animal Cell
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• Typical plant cell:
• chloroplasts
• rigid cell wall
Figure 4.4B
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Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
ORGANELLES OF THE ENDOMEMBRANE SYSTEM
Concept 6.3 The nucleus
• The largest organelle
– separated from the cytoplasm by the
nuclear envelope
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• Contains the cell’s DNA  directs cellular activities
Figure 4.5
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Endoplasmic Reticulum (ER):
Smooth ER vs. Rough ER
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Endoplasmic Reticulum (ER):
Smooth:
– Synthesizes lipids
– Processes toxins and drugs in liver cells
– Stores and releases calcium ions in muscle cells
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Rough endoplasmic reticulum
= Manufactures membranes and excreted proteins
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Ribosomes
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DNA
RNA
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DNA
1. Ribosomes
produces
RNA
polypeptide
where it folds into
3D shape.
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DNA
1. Ribosomes
produces
RNA
polypeptide
where it folds into
3D shape.
2. Short sugar chains
are attached
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DNA
1. Ribosomes
produces
RNA
polypeptide
where it folds into
3D shape.
2. Short sugar chains
are attached
3. Molecule
packaged into
transport vesicle
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DNA
1. Ribosomes
produces
RNA
polypeptide
where it folds into
3D shape.
2. Short sugar chains
are attached
3. Molecule
packaged into
transport vesicle
4. Transport vesicle
buds off ER
Golgi
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6.4 Golgi apparatus:
- Stacks of membranous sacs that receive and modify
ER products
- Finishes, sorts, and ships cell products
Cis face
Trans face
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Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
???????????????????????????????????????????
Starting with the DNA in the nucleus, describe
how a protein that will be secreted from a cell is
produced.
Hint: Endomembrane System!
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???????????????????????????????????????????
Starting with the DNA in the nucleus, describe how a
protein that will be secreted from a cell is produced.
Hint: Endomembrane System!
DNA RNA nuclear pore in nuclear envelope
Cytoplasm Ribosome on Rough ER polypeptide
into RER lumen folded and sugar added transport
vesicle Golgi transport vesicle Plasma mem.
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Endomembrane System
Rough ER
Golgi
Transport
vesicle
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Endomembrane System
Special case:
Rough ER
Golgi
Lysosome
-Digest food or
old organelles
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Lysosomal Disease
• Tay–Sachs disease
• Caused by insufficient activity of an Lysosomal
enzyme of neuronal cells. Lipids accumulate in
the brain and interfere with normal biological
processes.
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Vacuoles
Function in the general maintenance of the cell
Storage
- Starch
- Flower pigments
- Poisons
Figure 4.12A
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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
ENERGY-CONVERTING ORGANELLES
6.5 Chloroplasts: Convert solar energy to
chemical energy
• Found in plants and some protists
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Mitochondria:
• cellular respiration
• chemical energy in food
(glucose)  make ATP for
ALL cellular work
Figure 4.15
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Mitochondrial Disease
• MERRF syndrome (or Myoclonic Epilepsy
with Ragged Red Fibers)
• extremely rare:1/400,000 in Europe
lumps of diseased mitochondria accumulate in the
subsarcolemmal region of the muscle fiber
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THE CYTOSKELETON AND RELATED STRUCTURES
Concept 6.6: Cytoskeleton =cell’s internal skeleton
=helps organize its structure and activities
=network of protein fibers
Figure 4.16
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THE CYTOSKELETON AND RELATED STRUCTURES
Cytoskeleton: 3 Fibers
1.Microfilament
Movement/structure
Muscle cells
2.Intermediate
3.Microtubule
Structure
Movement
Hair
ER/golgi vesicles
Figure 4.16
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Cilia and flagella
Figure 4.17A
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LM 600
Colorized SEM 4,100
– Microtubule locomotor appendages that
protrude from certain cells
Figure 4.17B
THE CYTOSKELETON AND RELATED STRUCTURES
Microtubules
= helps organize
cellular activities
Figure 4.16
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CELL SURFACES AND JUNCTIONS
Concept 6.7 Cell surfaces
- protect
- support
- join cells
• Cells interact with their environments and each
other via their surfaces.
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• Plant cells
– Connect by plasmodesmata, which are
connecting channels
Figure 4.18A
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Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Animal Cell Surfaces
• Tight junctions- bind cells together into leak-proof
sheets
• Anchoring junctions- link animal cells into strong
tissues
• Gap junctions- allow substances to flow from cell
to cell
Figure 4.18B
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Small intestine
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Extracellular Matrix (EMC)
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FUNCTIONAL CATEGORIES OF ORGANELLES
• Eukaryotic organelles fall into one of four
functional groups
– Manufacturing?
– Breakdown?
– Energy processing?
– Support, movement, and communication
between cells?
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Review Ch. 5
4. Nucleic Acids- Monomers = 5 nucleotides
3 parts of the Monomer
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DNA or RNA monomer?
A
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Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Review
Ch. 6
Microscopy: Light vs. Electron microscope
Cell Fractionation WHY?
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Ch. 6 Review
Prokaryotic vs. Eukaryotic cells
Eukaryotic cells:
-Nucleus
-ER (smooth and rough)
-Ribosomes (free and bound)
-Golgi Body
-Endomemebrane system, parts?
-Lysosome
-Vacuoles
-Mitochondria
-Chloroplast
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings