Download Chapter 4 A Tour of the Cell

Chapter 4
A Tour of the Cell
PowerPoint Lectures for
Campbell Biology: Concepts & Connections, Seventh Edition
Reece, Taylor, Simon, and Dickey
© 2012 Pearson Education, Inc.
Lecture by Edward J. Zalisko
 Plans:
 Day 1) Notes: 4.1-4.4/ HW Packet, Assign project and talk
about cell cake
 Day 2) Cards
 Day 3) Cards
 Day 4) Review cards
 Day 5) Card Matching Game
 Day 6) Quiz
 Day 7) Cell Cake
 Day 8) test
 Do Now: What is life? Describe the characteristics of all
living things.
1) Nutrition
2) Respiration
3) Regulation
4) Reproduction
5) Synthesis
6) Transport
7) Excretion
8) Growth
Introduction
 Cells are the simplest collection of matter that can
live.
 Cells were first observed by Robert Hooke in 1665.
 Working with more refined lenses, Antoni van
Leeuwenhoek later described
– blood,
– sperm, and
– organisms living in pond water.
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Introduction
 Since the days of Hooke and Leeuwenhoek,
improved microscopes have vastly expanded our
view of the cell.
© 2012 Pearson Education, Inc.
Figure 4.0_1
Chapter 4: Big Ideas
Introduction to the Cell
The Endomembrane
System
The Nucleus and
Ribosomes
Energy-Converting
Organelles
The Cytoskeleton
and Cell Surfaces
Figure 4.0_2
INTRODUCTION TO THE CELL
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 1)LIGHT MICROSCOPE
 Common?
 Maximum Magnification?
 Magnification:
 Resolution:
 The most frequently used
 Light passes through a specimen, then through
glass lenses, and finally light is projected into the
viewer’s eye.
– Magnified up to 1,000 times
 Magnification is the increase in the apparent size of an object.
 Resolution is a measure of the clarity of an image. In other words, it is
the ability of an instrument to show two close objects as separate.
 Limited detail
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Figure 4.1A
Figure 4.1B
10 m
100 mm
(10 cm)
Length of
some nerve
and muscle
cells
Chicken
egg
10 mm
(1 cm)
Unaided eye
Human height
1m
Frog egg
10 µm
1 µm
100 nm
Most plant and
animal cells
Nucleus
Most bacteria
Mitochondrion
Smallest bacteria
Viruses
Ribosome
10 nm
Proteins
Lipids
1 nm
0.1 nm
Small molecules
Atoms
Electron microscope
100 µm
Paramecium
Human egg
Light microscope
1 mm
 2) ELECTRON MICROSCOPE (EM)
 How it works?
 Maximum magnification?
 limitiation?
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 1950s, scientists started using them to view the
ultrastructure of cells.
– Instead of light, EM uses a beam of electrons.
 Electron microscopes can
– resolve biological structures as small as 2 nanometers
and
– magnify up to 100,000 times.
– Specimen must be dead
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Figure 4.1E
 3) Scanning Electron Microscope (SEM)
 What can you study?
 How does it work?
 Scanning electron microscopes (SEM) study the
detailed architecture of cell surfaces.
– An electron beam to scan the surface which is usually
coated in gold,
– beam excites electrons on the surface
– an image is translated
Figure 4.1C
 4) Transmission Electron Microscope (TEM)
 What is it used for?
 How does it work?
 Transmission electron microscopes (TEM)
study the details of internal cell structure.
– Aims an electron beam through a thin section
– Section is stained with heavy metals
– Electrons that scatter create an image
– Uses electromagnets instead of lenses to bend
pathway of electron, magnifying specimen
.
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Figure 4.1D
 5) CELL THEORY/ SIZE
 What is the cell theory?
 Why are cells small?
 In the 1800s, these studies led to cell theory, which
states that
– all living things are composed of cells and
– all cells come from other cells.
 Cell size must
– be large enough to house DNA, proteins, and structures needed to
survive and reproduce, but
– remain small enough to allow for a surface-to-volume ratio that will
allow adequate exchange with the environment.
Figure 4.2A
1
3
1
3
Total volume
Total surface
area
Surface-tovolume ratio
27 units3
27 units3
54 units2
162 units2
2
6
 6) PLASMA MEMBRANE (CELL MEMBRANE)
 What is the cell membrane like? Where are the
proteins?
 How does it control the traffic of molecules across it?
 What things pass over easily?
 What things need help? How are they helped?
 The plasma membrane forms a flexible boundary between the living
cell and its surroundings.
 Phospholipids form a two-layer sheet called a phospholipid bilayer in
which
– hydrophilic heads face outward, exposed to water, and
– hydrophobic tails point inward, shielded from water.
 Membrane proteins are
– attached to the membrane surface or
– embedded in the phospholipid bilayer.
 Some proteins form channels or tunnels that allow ions and other
hydrophilic/polar molecules through
 O2 and CO2 are nonpolar and pass right over
 Other proteins serve as pumps, using energy to actively transport
molecules into or out of the cell.
© 2012 Pearson Education, Inc.
Figure 4.2B
Outside cell
Hydrophilic
heads
Hydrophobic
region of
a protein
Hydrophobic
tails
Phospholipid
Hydrophilic
region of
a protein
Inside cell
Channel
protein
Proteins
 7) PROKARYOTIC CELL
 Types of organisms?
 Common with eukaryotic cells?
 Different?
 What do they have on the outside?
 Attach to other things?
 Move?
 What do they lack?
 Bacteria and archaea
– Prokaryotic and eukaryotic cells have
– a plasma membrane
– chromosomes, ribosomes and cytoplasm
 The DNA is coiled into a region called the nucleoid, but no membrane
surrounds DNA
 The surface of prokaryotic cells may
– be surrounded by a complex cell wall,
– have a capsule surrounding the cell wall,
– have short projections that help attach to other cells or the
substrate,
– have longer projections called flagella (swim)
–
no true membrane bound organelles.
© 2012 Pearson Education, Inc.
Figure 4.3
Fimbriae
Ribosomes
Nucleoid
Plasma membrane
Cell wall
Bacterial
chromosome
A typical rod-shaped
bacterium
Capsule
Flagella
A TEM of the bacterium
Bacillus coagulans
Figure 4.3_1
Fimbriae
Ribosome
Nucleoid
Plasma membrane
Cell wall
Bacterial
chromosome
A typical rod-shaped
bacterium
Capsule
Flagella
Figure 4.3_2
Ribosome
Nucleoid
Plasma membrane
Cell wall
Capsule
A TEM of the bacterium
Bacillus coagulans
 8) EUKARYOTIC CELL
 What does it have that is missing in prokaryotes?
 What are the four functions?
 How are they achieved?
membrane-bound nucleus and
number of other organelles.
 The structures/organelles perform four basic functions.
1. The nucleus and ribosomes are involved in the genetic control of
the cell.
2. The endoplasmic reticulum, Golgi apparatus, lysosomes, vacuoles,
and peroxisomes are involved in the manufacture, distribution, and
breakdown of molecules.
3. Mitochondria in all cells and chloroplasts in plant cells are involved
in energy processing.
4. Structural support, movement, and communication between cells
are functions of the cytoskeleton, plasma membrane, and cell wall.
© 2012 Pearson Education, Inc.
 9) Plant and Animal Cell
 What does an animal cell have that is missing in a
plant?
 What does a plant have that is missing in an animal?
 What are the chemical reactions in the cell called?
 What are the little organs called?
Organelles: are the small structures with specific functions
Cellular metabolism: the many chemical activities of
cells, occurs within organelles
Animals only: Lysosomes and centrioles
Plant only: a rigid cell wall, chloroplasts, and a central
vacuole.
© 2012 Pearson Education, Inc.
Figure 4.4A
Rough
Smooth
endoplasmic endoplasmic
reticulum
reticulum
NUCLEUS:
Nuclear
envelope
Chromatin
Nucleolus
NOT IN MOST
PLANT CELLS:
Centriole
Lysosome
Peroxisome
Ribosomes
Golgi
apparatus
CYTOSKELETON:
Microtubule
Intermediate
filament
Microfilament
Mitochondrion
Plasma membrane
Figure 4.4B
NUCLEUS:
Nuclear envelope
Chromatin
Nucleolus
Golgi
apparatus
NOT IN ANIMAL
CELLS:
Central vacuole
Chloroplast
Cell wall
Plasmodesma
Mitochondrion
Peroxisome
Plasma membrane
Cell wall of
adjacent cell
Rough
endoplasmic
reticulum
Ribosomes
Smooth
endoplasmic
reticulum
CYTOSKELETON:
Microtubule
Intermediate
filament
Microfilament
THE NUCLEUS AND RIBOSOMES
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 10) NUCLEUS
 Function?
 What is inside?
 How is it kept separate?
 What organelle is inside? Function?
-
contains most of the cell’s DNA and
– controls the cell’s activities by directing protein synthesis by making
messenger RNA (mRNA).
 DNA is associated with many proteins in structures called
chromosomes. (46 for humans) / unorganized chromatin
 The nuclear envelope
– is a double membrane
– has pores that allow material in and out
 The nuclear envelope is attached to cellular membranes called the
endoplasmic reticulum.
 The nucleolus is
– a prominent structure in the nucleus
– the site of ribosomal RNA (rRNA) synthesis
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Figure 4.5
Two membranes
of nuclear envelope
Chromatin
Nucleolus
Pore
Endoplasmic
reticulum
Ribosomes
Nucleus
 11) RIBOSOMES
 What do they do?
 What are they made up of? Who makes them?
 Where are they found?
 Ribosomes are involved in the cell’s protein synthesis.
– Ribosomes are synthesized from rRNA produced in the nucleolus.
– Cells that must synthesize large amounts of protein have a large
number of ribosomes.
– Free ribosomes are
– suspended in the cytoplasm
– make proteins that function in cytoplasm.
– Bound ribosomes are
– attached to the endoplasmic reticulum (ER)
– associated with proteins packed in organelles or exported
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Figure 4.6
Ribosomes
ER
Cytoplasm
Endoplasmic
reticulum (ER)
Free ribosomes
Bound
ribosomes
Colorized TEM showing
ER and ribosomes
mRNA
Protein
Diagram of
a ribosome
THE ENDOMEMBRANE
SYSTEM
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 Many of the membranes within a eukaryotic cell
are part of the endomembrane system
 Some are physically connected and some are
related by the transfer of membrane segments by
tiny vesicles (sacs made of membrane).
 Many of these organelles work together in the
– synthesis,
– storage, and
– export of molecules.
 The endomembrane system includes
– the nuclear envelope, endoplasmic reticulum (ER),
Golgi apparatus, lysosomes, vacuoles, and the plasma
membrane.
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 12) Rough Endoplasmic Reticulum
 What does it do?
 What does it have on it?
 Steps:
 Has ribosomes attached
 Rough ER makes
– additional membrane
– ER ribosomes synthesize, modify, and package proteins to be
transported to other organelles or secreted by cell
– Steps
1. Polypeptide synthesized by ribosomes according to mRNA, as it
enters it takes on its 3D shape
2. Short sugars(address) added creating a glycoprotein
3. Packaged into a vesicle
4. Off to the Golgi
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Figure 4.8B
Transport vesicle
buds off
4
Secretory
protein
inside transport vesicle
mRNA
Ribosome
3
Sugar
chain
1
2
Polypeptide
Glycoprotein
Rough ER
 13) Smooth Endoplasmic Reticulum
 3 functions?
1. Produces enzymes important in the synthesis of lipids,
oils, phospholipids, and steroids.
2. Other enzymes help process drugs, alcohol, and other
potentially harmful substances.
3. Some smooth ER helps store calcium ions.
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Figure 4.8A
Nuclear
envelope
Smooth ER
Ribosomes
Rough ER
Figure 4.8A_1
Smooth ER
Ribosome
Rough ER
 14) Golgi Apparatus
 Function?
 Steps?
 Serves as a molecular warehouse and finishing factory for products
(proteins) manufactured by the ER.
1. Products travel in transport vesicles from the ER to the Golgi
apparatus.
2. One side of the Golgi apparatus functions as a receiving dock for
the product and the other as a shipping dock.
3. Products are modified by enzymes as they go from one side of the
Golgi apparatus to the other and travel in vesicles to other sites.
–
Change sugars, add molecular tags like P to help sort
proteins
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Figure 4.9
“Receiving” side
of Golgi
apparatus
Golgi
apparatus
1
Transport
vesicle
from ER
2
Transport
vesicle from
the Golgi
3
4
4
“Shipping”
side of Golgi
apparatus
Golgi apparatus
 15) Lysosome
 What is it?
 How is it created?
 Steps?
 Membranous sac containing digestive enzymes.
– The enzymes and membrane are produced by the ER
and transferred to the Golgi apparatus for processing.
– Safely isolate these potent enzymes
 Digests food particles engulfed by a cell
1. A food vacuole binds with a lysosome.
2. The enzymes in the lysosome digest the food.
3. The nutrients are then released into the cell.
 Remove or recycle damaged parts of a cell.
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Figure 4.10A_s1
Digestive
enzymes
Lysosome
Plasma membrane
Figure 4.10A_s2
Digestive
enzymes
Lysosome
Food vacuole
Plasma membrane
Figure 4.10A_s3
Digestive
enzymes
Lysosome
Food vacuole
Plasma membrane
Figure 4.10A_s4
Digestive
enzymes
Lysosome
Digestion
Food vacuole
Plasma membrane
Figure 4.10B_s1
Lysosome
Vesicle containing
damaged mitochondrion
Figure 4.10B_s2
Lysosome
Vesicle containing
damaged mitochondrion
Figure 4.10B_s3
Lysosome
Digestion
Vesicle containing
damaged mitochondrion
 16)VACUOLES
 Functions in protists
 Functions in plants:
 Variety of functions.
– Food vacuole
– Some fresh water protists have contractile vacuoles that
help to eliminate extra water
– In plants, vacuoles may
– have digestive functions,
– contain pigments, or
– contain poisons that protect the plant
– Large central vacuole
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Figure 4.11A
Contractile
vacuoles
Nucleus
Figure 4.11B
Central vacuole
Chloroplast
Nucleus
 17)PEROXISOME
 Did it come from the EMS?
 What does it do?
 Do not originate from EM system
 Break down fatty acids to be used as fuel
 In your liver, they detox alcohol
– an enzyme adds H to oxygen to make H2O2 or hydrogen
peroxide
– Other enzymes then convert this toxic substance into a
water
4.12 A review of the structures involved in
manufacturing and breakdown
 The following figure summarizes the relationships
among the major organelles of the endomembrane
system.
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Figure 4.12
Nucleus
Nuclear
membrane
Rough ER
Transport
vesicle from
Golgi to
plasma
membrane
Smooth
ER
Transport
vesicle from ER
to Golgi
Golgi
apparatus
Lysosome
Vacuole
Plasma
membrane
ENERGY-CONVERTING
ORGANELLES
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 18)MITOCHONDRIA
 What do they do?
 How?
 Compartments.
 Carries out cellular respiration
 Converts chemical energy in foods to chemical energy in ATP
(adenosine triphosphate).
 Mitochondria have two internal compartments.
1. The intermembrane space is the narrow region between the inner
and outer membranes.
2. The mitochondrial matrix contains
– the mitochondrial DNA,
– ribosomes,
– many enzymes that catalyze some of the reactions of cellular
respiration.
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Figure 4.13
Mitochondrion
Outer
membrane
Intermembrane
space
Inner
membrane
Cristae
Matrix
 19) CHLOROPLAST
 Process?
 Compartments?
 Photosynthesizing organelles
 Photosynthesis is the conversion of light energy from the sun to the
chemical energy of sugar molecules.
 Compartments.
– Between the outer and inner membrane is a thin intermembrane
space.
– Inside the inner membrane is
– a thick fluid called stroma that contains the chloroplast DNA,
ribosomes, and many enzymes and
– a network of interconnected sacs called thylakoids.
– In some regions, thylakoids are stacked like poker chips.
Each stack is called a granum, where green chlorophyll
molecules trap solar energy.
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Figure 4.14
Inner and
outer
membranes
Granum
Chloroplast
Stroma
Thylakoid
 20)Endosymbiont Theory
 What is it?
 What organelles is it about?
 Why is this thought to be true?
 Mitochondria and chloroplasts have
– DNA and
– ribosomes.
 The structure of this DNA and these ribosomes is very
similar to that found in prokaryotic cells.
 The endosymbiont theory proposes that
– mitochondria and chloroplasts were formerly small
prokaryotes and they began living within larger cells.
© 2012 Pearson Education, Inc.
Figure 4.15
Mitochondrion
Nucleus
Endoplasmic
reticulum
Some
cells
Engulfing
of oxygenusing
prokaryote
Engulfing of
photosynthetic
prokaryote
Chloroplast
Host cell
Mitochondrion
Host cell
THE CYTOSKELETON AND
CELL SURFACES
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 21)CYTOSKELETON
 Function:
 3 types: Functions?
 A network of protein fibers, which functions in structural
support and motility.
 Motility and cellular regulation result when the cytoskeleton
interacts with proteins called motor proteins.
 The cytoskeleton is composed of three kinds of fibers.
1. Microfilaments (actin filaments) support the cell’s
shape and are involved in motility.
2. Intermediate filaments reinforce cell shape and anchor
organelles.
3. Microtubules (made of tubulin) give the cell rigidity and
act as tracks for organelle movement.
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Figure 4.16
Nucleus
Nucleus
Actin subunit
7 nm
Microfilament
Fibrous subunits
Tubulin subunits
10 nm
25 nm
Intermediate filament
Microtubule
 22)Cilia and Flagella
 Function in multicellular organisms
 Function in single celled eukaryotes (protists) and
prokaryotes
 Structure
 multicellular organisms
–
Cells that sweep mucus out of our lungs have cilia and animal sperm are
flagellated
Protists and Prokaryotes
 A flagellum, longer than cilia, propels a cell by an undulating, whiplike motion.
 Cilia work more like the oars of a crew boat.
 Structure
 Both are made of microtubules wrapped in an extension of the plasma
membrane.
 A ring of nine microtubule doublets surrounds a central pair of microtubules.
This arrangement is
–
called the 9 + 2 pattern
–
anchored in a basal body with nine microtubule triplets arranged in a ring.
 Cilia and flagella move by bending motor proteins called dynein feet.
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Figure 4.17A
Cilia
Figure 4.17B
Flagellum
Figure 4.17C
Outer microtubule doublet
Central
microtubules
Radial spoke
Dynein proteins
Plasma membrane
Figure 4.17C_1
Outer
microtubule
doublet
Central
microtubules
Radial spoke
Dynein proteins
4.18 CONNECTION: Problems with sperm
motility may be environmental or genetic
 In developed countries over the last 50 years, there
has been a decline in sperm quality.
 The causes of this decline may be
– environmental chemicals or
– genetic disorders that interfere with the movement of
sperm and cilia. Primary ciliary dyskinesia (PCD) is a
rare disease characterized by recurrent infections of the
respiratory tract and immotile sperm.
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Figure 4.18
 23)Extracellular Matrix
 Function:
 Components:
 Most Abundant?
 Integrin functions
 Animal cells synthesize and secrete an elaborate
extracellular matrix (ECM) that
– helps hold cells together in tissues and
– protects and supports the plasma membrane.
 The ECM may attach to a cell through
glycoproteins that then bind to membrane proteins
called integrins. Integrins span the plasma
membrane and connect to microfilaments of the
cytoskeleton.
© 2012 Pearson Education, Inc.
Figure 4.19
Glycoprotein
complex
with long
polysaccharide
EXTRACELLULAR FLUID
Collagen fiber
Connecting
glycoprotein
Integrin
Plasma
membrane
CYTOPLASM
Microfilaments
of cytoskelton
 24) Animal Cell Junctions:
 Functions:
 3 Types described
 Adjacent cells communicate, interact, and adhere
through specialized junctions between them.
– Tight junctions prevent leakage of extracellular fluid
across a layer of epithelial cells.
– Anchoring junctions fasten cells together into sheets.
– Gap junctions are channels that allow molecules to
flow between cells.
© 2012 Pearson Education, Inc.
Figure 4.20
Tight junctions
prevent fluid from
moving between cells
Tight junction
Anchoring
junction
Gap junction
Plasma membranes
of adjacent cells
Extracellular matrix
 25) Plasmodesmata
 Type of cells
 Function
 A plant cell has a rigid cell wall that
– protects and provides skeletal support that helps keep
the plant upright against gravity and
– is primarily composed of cellulose.
 Plant cells have cell junctions called
plasmodesmata that serve in communication
between cells.
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Figure 4.21
Plant cell
walls
Vacuole
Plasmodesmata
Primary cell wall
Secondary cell wall
Plasma membrane
Cytoplasm
4.22 Review: Eukaryotic cell structures can be
grouped on the basis of four basic functions
 Eukaryotic cell structures can be grouped on the
basis of four functions:
1. genetic control,
2. manufacturing, distribution, and breakdown,
3. energy processing, and
4. structural support, movement, and communication
between cells.
© 2012 Pearson Education, Inc.
Table 4.22
Table 4.22_1
Table 4.22_2
You should now be able to
1. Describe the importance of microscopes in
understanding cell structure and function.
2. Describe the two parts of cell theory.
3. Distinguish between the structures of prokaryotic
and eukaryotic cells.
4. Explain how cell size is limited.
5. Describe the structure and functions of cell
membranes.
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You should now be able to
6. Explain why compartmentalization is important in
eukaryotic cells.
7. Compare the structures of plant and animal cells.
Note the function of each cell part.
8. Compare the structures and functions of
chloroplasts and mitochondria.
9. Describe the evidence that suggests that
mitochondria and chloroplasts evolved by
endosymbiosis.
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You should now be able to
10. Compare the structures and functions of
microfilaments, intermediate filaments, and
microtubules.
11. Relate the structure of cilia and flagella to their
functions.
12. Relate the structure of the extracellular matrix to
its functions.
13. Compare the structures and functions of tight
junctions, anchoring junctions, and gap junctions.
© 2012 Pearson Education, Inc.
You should now be able to
14. Relate the structures of plant cell walls and
plasmodesmata to their functions.
15. Describe the four functional categories of
organelles in eukaryotic cells.
© 2012 Pearson Education, Inc.
Figure 4.UN02
Figure 4.UN03
a.
l.
b.
c.
k.
j.
i.
h.
d.
g.
e.
f.