Figure 6-01
Investigating Cell Structure and
Function
1. Cell Theory
2. Microscopya. History
b. Types
3. Studying cell organelles
a. Cell homogenization
b. Cell Fractionation
LE 6-2
10 m
Human height
Length of some
nerve and
muscle cells
0.1 m
Chicken egg
Unaided eye
1m
1 cm
Frog egg
100 µm
Most plant and
animal cells
10 µm
Nucleus
Most bacteria
1 µm
100 nm
Mitochondrion
Smallest bacteria
Viruses
Ribosomes
10 nm
Proteins
Lipids
1 nm
Small molecules
0.1 nm
Atoms
Electron microscope
Measurements
1 centimeter (cm) = 10–2 meter (m) = 0.4 inch
1 millimeter (mm) = 10–3 m
1 micrometer (µm) = 10–3 mm = 10–6 m
1 nanometer (nm) = 10–3 µm = 10–9 m
Light microscope
1 mm
Table 7.1 Different Types of Light Microscopy: A Comparison
LE 6-3a
Brightfield (unstained
specimen)
50 µm
Brightfield (stained
specimen)
Phase-contrast
LE 6-3b
Differentialinterferencecontrast (Nomarski)
Fluorescence
50 µm
Confocal
50 µm
LE 6-4
Scanning electron
microscopy (SEM)
Transmission electron
microscopy (TEM)
Cilia
Longitudinal
section of
cilium
1 µm
Cross section
of cilium
1 µm
LE 6-4a
Cilia
Scanning electron
microscopy (SEM)
1 µm
LE 6-4b
Longitudinal
section of
cilium
Cross section
of cilium
1 µm
Transmission electron
microscopy (TEM)
LE 6-9a
ENDOPLASMIC RETICULUM (ER
Nuclear envelope
Flagellum
Rough ER
Smooth ER
NUCLEUS
Nucleolus
Chromatin
Centrosome
Plasma membrane
CYTOSKELETON
Microfilaments
Intermediate filaments
Microtubules
Ribosomes:
Microvilli
Golgi apparatus
Peroxisome
Mitochondrion
Lysosome
In animal cells but not plant cells:
Lysosomes
Centrioles
Flagella (in some plant sperm)
Inner Life of A Cell
• http://www.studiodaily.com/main/searchlist
/6850.html
LE 6-5a
Homogenization
Tissue
cells
Differential centrifugation
Homogenate
LE 6-5b
1000 g
(1000 times the
force of gravity)
10 min
Supernatant poured
into next tube
20,000 g
20 min
80,000 g
60 min
Pellet rich in
nuclei and
cellular debris
150,000 g
3 hr
Pellet rich in
mitochondria
(and chloroplasts if cells
are from a plant)
Pellet rich in
“microsomes”
(pieces of plasma
membranes and
cells’ internal
membranes)
Pellet rich in
ribosomes
Cell Structure
1. Basic requirements to be a cell
•
Cytoplasm
•
DNA
•
Ribosome
•
Cell membrane
2.
Prokaryotic and eukaryotic cells
3. Limitations to cell size
a. Lower limits
b. Upper limits-SA/volume ratio
Prokaryotic and Eukaryotic Cells
LE 6-6
Pili
Nucleoid
Ribosomes
Plasma
membrane
Bacterial
chromosome
Cell wall
Capsule
0.5 µm
Flagella
A typical
rod-shaped
bacterium
A thin section through the
bacterium Bacillus
coagulans (TEM)
LE 6-7
Surface area increases while
Total volume remains constant
5
1
1
Total surface area
(height x width x
number of sides x
number of boxes)
6
150
750
Total volume
(height x width x length
X number of boxes)
1
125
125
Surface-to-volume
ratio
(surface area  volume)
6
1.2
6
An overview of animal cell structure
1.
2.
3.
a.
b.
c.
d.
e.
4.
5.
Nucleus
Ribosomes
Endomembrane System
RER & SER
Vesicles
Golgi apparatus
Vacuoles
Lysosomes
Mitochondria
Cytoskeleton
LE 6-9a
ENDOPLASMIC RETICULUM (ER
Nuclear envelope
Flagellum
Rough ER
Smooth ER
NUCLEUS
Nucleolus
Chromatin
Centrosome
Plasma membrane
CYTOSKELETON
Microfilaments
Intermediate filaments
Microtubules
Ribosomes:
Microvilli
Golgi apparatus
Peroxisome
Mitochondrion
Lysosome
In animal cells but not plant cells:
Lysosomes
Centrioles
Flagella (in some plant sperm)
LE 6-8
Outside of cell
Carbohydrate side chain
Hydrophilic
region
Inside of cell 0.1 µm
Hydrophobic
region
Hydrophilic
region
TEM of a plasma membrane
Phospholipid
Proteins
Structure of the plasma membrane
What is contained in the
nucleus of a cell?
DNA
Chromosomes
Genes
R-rna
All of the above
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0%
DN
A
1.
2.
3.
4.
5.
LE 6-10
Nucleus
Nucleus
1 µm
Nucleolus
Chromatin
Nuclear envelope:
Inner membrane
Outer membrane
Nuclear pore
Pore
complex
Rough ER
Surface of nuclear envelope
Ribosome
1 µm
0.25 µm
Close-up of nuclear
envelope
Pore complexes (TEM)
Nuclear lamina (TEM)
What is the function of
ribosomes?
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n
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In
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A
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he
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0%
Pr
ot
ei
n
1. Protein synthesis
2. DNA synthesis
3. Intracellular
digestion
4. Transport of
proteins outside of
the cell
LE 6-11
Ribosomes
ER
Cytosol
Endoplasmic
reticulum (ER)
Free ribosomes
Bound ribosomes
Large
subunit
Small
subunit
0.5 µm
TEM showing ER
and ribosomes
Diagram of
a ribosome
There is a difference in the make-up of
cytoplasmic eukaryotic ribosomes and prokaryotic
ribosomes
1. True
2. False
se
0%
Fa
l
Tr
ue
0%
Proteins that are secreted from
a cell are produced by:
1. Membrane-bound
ribosomes
2. Free ribosomes
0%
M
em
br
a
os
om
ib
Fr
ee
r
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-b
ou
nd
rib
o.
..
es
0%
Secreted proteins are carried
away from the ER by:
1. The golgi
apparatus
2. Lysosomes
3. Mitochondria
4. vesicles
Th
e
nd
ria
ch
o
ito
Ly
so
so
m
0%
ve
s ic
le
s
0%
es
0%
M
go
l
gi
ap
pa
r
at
us
0%
LE 6-12
Smooth ER
Rough ER
Nuclear
envelope
ER lumen
Cisternae
Ribosomes
Transport vesicle
Smooth ER
Transitional ER
Rough ER
200 nm
If a secreted protein needs to be chemically modified after
it leaves the ER in a vesicle, it will go to:
A lysosome
Mitochondria
A storage vacuole
The Golgi
apparatus
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le
pp
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ac
uo
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a
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o
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0%
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0%
A
1.
2.
3.
4.
LE 6-16-3
Nucleus
Rough ER
Smooth ER
Nuclear envelope
cis Golgi
Transport vesicle
Plasma
membrane
trans Golgi
Vesicles from either the ER or the Golgi that contain
proteins involved in intracellular digestion fuse to form this
cell organelle
1. Storage vacuole
2. Mitochondria
3. Lysosome
ch
o
ito
M
e
le
cu
o
va
ge
St
or
a
0%
Ly
so
so
m
0%
nd
ria
0%
Lysosomes are involved in destroying “worn
out” cell organelles:
1. True
2. False
se
0%
Fa
l
Tr
ue
0%
Up to 5 optional points
• You have 3 minutes to write a short
answer to this question:
• Why is it important that the pH of a
lysosome is acidic compared to the
cytoplasm of the cell?
LE 6-14a
1 µm
Nucleus
Lysosome
Lysosome contains Food vacuole Hydrolytic
active hydrolytic
enzymes digest
fuses with
enzymes
food particles
lysosome
Digestive
enzymes
Plasma
membrane
Lysosome
Digestion
Food vacuole
Phagocytosis: lysosome digesting food
LE 6-14b
Lysosome containing
two damaged organelles
1 µm
Mitochondrion
fragment
Peroxisome
fragment
Lysosome fuses with
vesicle containing
damaged organelle
Hydrolytic enzymes
digest organelle
components
Lysosome
Digestion
Vesicle containing
damaged mitochondrion
Autophagy: lysosome breaking down
damaged organelle
Malfunctions within a lysosome
can cause diseases.
1. True
2. False
se
0%
Fa
l
Tr
ue
0%
Vacuoles
Ca
n
be
e
0%
ab
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of
t
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w
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fo
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ed
ce
st
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.
su
bs
ta
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by
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m
M
ay
fo
r
be
Ca
n
0%
h.
..
0%
Ca
n
1. Can be formed by
endocytosis
2. May store
substances the cell
will need later
3. Can be formed by
vesicles joining
together
4. Can be filled with
water
5. All of the above
LE 7-14
Filling vacuole
Contracting vacuole
50 µm
50 µm
This cell organelle has a structure adapted for
making ATP during cellular respiration.
Lysosome
Nucleus
Vacuole
Golgi apparatus
mitochondria
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Nu
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us
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0%
Ly
so
so
m
1.
2.
3.
4.
5.
LE 6-17
Mitochondrion
Intermembrane space
Outer
membrane
Free
ribosomes
in the
mitochondrial
matrix
Inner
membrane
Cristae
Matrix
Mitochondrial
DNA
100 nm
The Cytoskeleton
1. Made up of 3 elements
a. Microtubules
b. Microfilaments
c. Intermediate filaments
2. Functions-diverse including maintaining
cells shape; motility; contraction; and
organelle movement
LE 6-20
Microtubule
Microfilaments
0.25 µm
Table 6-1a
LE 6-22
Centrosome
Microtubule
Centrioles
0.25 µm
Longitudinal section Microtubules
of one centriole
Cross section
of the other centriole
Cilia and Flagella
• Cell Movement
LE 6-23a
Direction of swimming
Motion of flagella
5 µm
LE 6-23b
Direction of organism’s movement
Direction of
active stroke
Motion of cilia
Direction of
recovery stroke
15 µm
This cell organelle contains 2 compartments
separated by a membrane, which is necessary for
chemiosmosis to occur
Golgi apparatus
Mitochondria
RER
Lysosome
vacuole
M
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0%
va
c
uo
l
e
e
RE
R
0%
Ly
so
so
m
ito
ch
o
ar
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ia
pp
0%
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0%
Go
lg
1.
2.
3.
4.
5.
Which of the following
statements is/are true?
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B
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B
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an
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4.
5.
6.
A
3.
cy
to
sk
el
et
Th
...
e
cy
to
sk
el
et
Th
...
e
cy
to
sk
el
et
...
2.
The cytoskeleton is composed
of protein
The cytoskeleton is involved
in the segregation of
chromosomes during mitosis
The cytoskeleton can
reorganize by
polymerizing/depolymerizing
A and B
B and C
All of the above
Th
e
1.
LE 6-24a
Microtubules
Plasma
membrane
Basal body
0.5 µm
LE 6-24b
0.1 µm
Outer microtubule
doublet
Dynein arms
Central
microtubule
Cross-linking
proteins inside
outer doublets
Radial
spoke
0.5 µm
Plasma
membrane
LE 6-25b
Cross-linking
proteins inside
outer doublets
Anchorage
in cell
Effect of cross-linking proteins
Wavelike motion
ATP
Organelle Movement
• Position of organelles not fixed in the cell
LE 6-21a
Vesicle
ATP
Receptor for
motor protein
Motor protein
(ATP powered)
Microtubule
of cytoskeleton
LE 6-21b
Microtubule
Vesicles
0.25 µm
Table 6-1c
LE 6-26
Microvillus
Plasma membrane
Microfilaments (actin
filaments)
Intermediate filaments
0.25 µm
Table 6-1b
LE 6-27a
Muscle cell
Actin filament
Myosin filament
Myosin arm
Myosin motors in muscle cell contraction
LE 6-27b
Cortex (outer cytoplasm):
gel with actin network
Inner cytoplasm: sol
with actin subunits
Extending
pseudopodium
Amoeboid movement
LE 6-27c
Nonmoving
cytoplasm (gel)
Chloroplast
Streaming
cytoplasm
(sol)
Vacuole
Parallel actin
filaments
Cytoplasmic streaming in plant cells
Cell wall
Dyneine walking is a key event in this
cellular process:
0%
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0%
0%
Ch
em
io
sm
Am
os
oe
is
bo
id
m
ov
em
...
Cy
to
ke
ne
s is
M
ot
ili
ty
us
in
g.
Al
..
lo
ft
he
ab
o.
..
1. Chemiosmosis
2. Amoeboid
movement
3. Cytokenesis
4. Motility using
flagella
5. All of the above
Plant Cell Structure
1. All of the same organelles and structures
that are in animals plus
a. Cell wall
b. Large central vacuole
c. Chloroplasts
LE 6-9b
Nuclear
envelope
NUCLEUS
Nucleolus
Chromatin
Centrosome
Rough
endoplasmic
reticulum
Smooth
endoplasmic
reticulum
Ribosomes
(small brown dots)
Central vacuole
Golgi
apparatus
Microfilaments
Intermediate
filaments
Microtubules
CYTOSKELETON
Mitochondrion
Peroxisome
Chloroplast
Plasma
membrane
Cell wall
Plasmodesmata
Wall of adjacent cell
In plant cells but not animal cells:
Chloroplasts
Central vacuole and tonoplast
Cell wall
Plasmodesmata
LE 6-28
Central
vacuole
of cell
Plasma
membrane
Secondary
cell wall
Primary
cell wall
Central
vacuole
of cell
Middle
lamella
1 µm
Central vacuole
Cytosol
Plasma membrane
Plant cell walls
Plasmodesmata
LE 6-15
Central vacuole
Cytosol
Tonoplast
Nucleus
Central
vacuole
Cell wall
Chloroplast
5 µm
LE 6-18
Chloroplast
Ribosomes
Stroma
Chloroplast
DNA
Inner and outer
membranes
Granum
1 µm
Thylakoid
LE 6-19
Chloroplast
Peroxisome
Mitochondrion
1 µm
This cell organelle contains 2 compartments
separated by a membrane, which is necessary for
chemiosmosis to occur
Golgi apparatus
Mitochondria
RER
Chloroplast
2 and 4
M
nd
2a
pl
a
or
o
0%
4
0%
st
RE
R
0%
Ch
l
ito
ch
o
ar
a
ia
pp
0%
nd
ria
tu
.. .
0%
Go
lg
1.
2.
3.
4.
5.
Because plant cells have a large central
water vacuole, they must also have:
Chloroplasts
Lysosomes
Mitochondria
A cell wall
RER
al
ce
ll w
0%
RE
R
0%
l
0%
A
0%
Ly
so
so
m
es
M
ito
ch
on
dr
ia
or
o
pl
a
st
s
0%
Ch
l
1.
2.
3.
4.
5.
Plays a role in cytoplasmic streaming, amoeboid
movement, and muscle contraction:
1. Microfilaments
2. Intermediate
filaments
3. Microtubules
4. Dyneine walking
5. All of the above
kin
of
t
w
he
al
0%
ab
o.
..
.. .
0%
es
Dy
ne
in
e
icr
M
ed
ia
te
ot
ub
ul
s
en
t
In
te
rm
of
ila
m
icr
M
0%
Al
l
0%
f ..
.
0%
These in class clicker questions
are helpful
Strongly Agree
Agree
Neutral
Disagree
Strongly Disagree
0%
ng
ly
Di
sa
gr
ee
gr
ee
0%
St
ro
l
0%
Di
sa
Ag
r
ee
0%
Ne
ut
ra
ng
ly
Ag
re
e
0%
St
ro
1.
2.
3.
4.
5.
Cell Surrface
Molecules/Connections
1. Cell surface molecules (glycocalyx)
2. Cell Connections-Plants
a. Plasmodesmata
3. Cell connections-Animals
a. Tight junctions
b. Desmosomes
c. Gap junctions
LE 6-29a
Collagen
fiber
EXTRACELLULAR FLUID
Fibronectin
Plasma
membrane
Integrin
CYTOPLASM
Microfilaments
Proteoglycan
complex
LE 6-30
Cell walls
Interior
of cell
Interior
of cell
0.5 µm
Plasmodesmata
Plasma membranes
LE 6-31
Tight junctions prevent
fluid from moving
across a layer of cells
Tight junction
0.5 µm
Tight junction
Intermediate
filaments
Desmosome
1 µm
Space
between
cells
Gap
junctions
Plasma membranes
of adjacent cells
Gap junction
Extracellular
matrix
0.1 µm
5 µm
LE 6-32