04 Lecture ModV1

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BIOLOGY Life on Earth
WITH PHYSIOLOGY 11th Edition
4
Cell Structure
and Function
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Chapter 4 At a Glance
•4.1 What Is the Cell Theory?
•4.2 What Are the Basic Attributes of Cells?
•4.3 What Are the Major Features of
Eukaryotic Cells?
•4.4 What Are the Major Features of
Prokaryotic Cells?
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Learning Objectives
Lg1 Summarize the cell theory.
Lg2 Compare and contrast prokaryotic and eukaryotic cells.
Lg3 Describe the major structures of animal cells and their
functions.
Lg4 Describe the structure and function of organelles that are
found in plant, but not animal, cells.
Lg5 Explain the structure, function, and movement of
eukaryotic cilia and flagella.
Lg6 Describe the structure and function of the nucleus, and
compare it to the nucleoid region of prokaryotic cells.
Lg7 List the parts of the endomembrane system and explain
how they are interconnected.
Lg8 Describe the structure and function of both the surface
and the internal features of bacterial cells.
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4.1 What Is the Cell Theory?
• The cell theory states that cells are the basic
units of life
• Three principles comprise the cell theory
• Every living organism is made of one or more cells
and cell products.
• The smallest organisms are single cells, and cells are
the functional units of multicellular organisms
• All cells arise from preexisting cells
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4.2 Basic Attributes of Cells
• Most cells range in size from about 1 to 100
micrometers (µm) in diameter
• Cells need to exchange nutrients and wastes with the
environment by diffusion.
• Larger cells have LOWER surface to volume ratio (d2/
d3 = 1/d) than smaller cells. Thus, larger cells are not
as effective in nutrient/waste.
• Experiment to demonstrate this principle. (1:25)
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Figure 4-1
100 m
10 m
1m
0.1 m
1 cm
1 mm
100 m
10 m
1 m
100 nm
10 nm
1 nm
0.1 nm
longest
python
DNA
house fly
most
eukaryotic
cells
apple
tallest redwood
tree
crab
louse
human
flu virus
C
most
prokaryotic
cells
hemoglobin
carbon
atom
human eye
light microscope
electron microscope
© 2017 Pearson
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4.2 Basic Attributes of Cells?
• All cells share common features
• Include plasma membrane
• Include cytoplasm
• Use DNA as hereditary blueprint
• Use RNA to copy the blueprint and guide
construction of cell parts.
The statement that “every cell has a nucleus” is false.
Why?
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4.2 Basic Attributes of Cells
Plasma Membrane
• Phospholipid bilayer interspersed with
cholesterol
• Barrier between interior and exterior of cell
• Embedded proteins
• Communication portals
• Regulate passage of molecules and ions
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Figure 4-2 The plasma membrane
interstitial fluid (outside)
carbohydrate
glycoprotein
A phospholipid bilayer
helps to isolate the
cell’s contents
Proteins help the cell
communicate with
its environment
channel protein
membrane protein
cytoskeleton
cytosol
4.2 Basic Attributes of Cells?
Cytoplasm
• All cells contain cytoplasm
• The cytoplasm consists of all the fluid and
structures that lie inside the plasma membrane but
outside of the nucleus
• The fluid portion of the cytoplasm (cytosol)
contains water, salts, and organic molecules
• Most of the cell’s metabolic activities occur in the
cell cytoplas
• Cytoskeleton
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Figure 4-3 A generalized animal cell
microfilaments
nuclear envelope
nuclear pore
nucleus
chromatin (DNA)
nucleolus
cytosol
microtubules
(cytoskeleton)
flagellum
(propels
sperm cell)
basal body
rough
endoplasmic
reticulum
vesicle
intermediate
filaments
(cytoskeleton)
cytoplasm
Golgi
apparatus
centriole
ribosomes
on rough
ER
polyribosome
lysosome
smooth
endoplasmic
reticulum
vesicles releasing
substances from
the cell
mitochondrion
plasma
membrane
free ribosome
Figure 4-4 A generalized plant cell
nucleus
microtubules
(cytoskeleton)
nuclear envelope
nuclear pore
chromatin
nucleolus
ribosomes
intermediate
filaments
(cytoskeleton)
cell walls of adjoining
plant cells
chloroplast
cytoplasm
rough
endoplasmic
reticulum
smooth
endoplasmic
reticulum
Golgi apparatus
central
vacuole
vesicle
mitochondrion
cell wall
plasma
membrane
plasmodesmata
cytosol
plastid
free
ribosome
4.2 Basic Attributes of Cells
DNA and RNA
• All cells use DNA as a hereditary blueprint
and RNA to copy the blueprint and guide
construction of cell parts
• All cells use DNA (deoxyribonucleic acid) as a
hereditary blueprint
• All cells use RNA (ribonucleic acid) to copy the
blueprint and to guide construction of proteins
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4.3 Variations in cell types
• There are two basic types of cells:
prokaryotic and eukaryotic
• Prokaryotic (“before the nucleus”) cells form the
bodies of bacteria and archaea, the simplest forms of
life
• Eukaryotic (“true nucleus”) cells form the bodies of
animals, plants, fungi, and protists
• The cytoplasm of eukaryotic cells includes a
variety of organelles, such as the nucleus and
mitochondria
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4.3 Eukaryotic Cells
Nucleus
• The nucleus, containing DNA, is the control
center of the eukaryotic cell
• The nucleus is the control center of the eukaryotic
cell and has three major parts
• Nuclear envelope
• Chromatin
• Nucleolus
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Figure 4-9
nuclear
envelope
nuclear
pores
ribosomes
nuclear pores with
nuclear pore complex
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4.3 Eukaryotic Cells
Nucleus
• Chromatin
• DNA molecules and their associated proteins
• Nuclear material within nucleus
• Extremely long, indistinguishable strands when a cell is not
dividing (most of the time)
• The nuclear envelope allows selective exchange
of materials
• consists of a double membrane perforated by nuclear pores
• perforated with tiny protein-lined nuclear pores that allow
water, ions, and small molecules to pass freely
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4.3 Eukaryotic Cells
Nucleus
• The nucleolus is the site of ribosome
assembly
• Eukaryotic nuclei contain at least one nucleolus, the
site of ribosome synthesis
• A ribosome is a small particle composed of
ribosomal RNA and proteins
• Composed of ribosomal RNA (rRNA), DNA, proteins,
and ribosomes
• Because proteins are synthesized in the cytoplasm,
protein blueprints, called messenger RNA (mRNA),
must leave the nucleus through the nuclear pores.
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4.3 Eukaryotic Cells
Cytoskeleton
• The cytoskeleton regulates the following
cell properties:
• Cell shape
• Cell movement
• Organelle movement
• Cell division (centriole and mitotic spindles that
separate chromosomes- microtubule)
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4.3 Eukaryotic Cells
Cytoskeleton
• The cytoskeleton is composed of three
types of protein fibers
• Thin microfilaments, e.g. actin.
• Medium-sized intermediate filaments (not moving)
• Thick microtubules (tubulin)
• Animation (microtubules)
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Figure 4-7
subunit
ribosomes
rough endoplasmic
reticulum
25 nm
microfilaments (red)
Microtubules: Composed of pairs of different
polypeptides in a helical arrangement
subunit
10 nm
Intermediate filaments: Composed of
ropelike bundles of various proteins
subunits
cell membrane
mitochondrion
(a) Cytoskeleton
© 2017 Pearson Education, Inc.
7 nm
Microfilaments: Composed of actin proteins
that resemble twisted double strands of beads
DNA in
nucleus (blue)
microtubules (green)
(b) Light micrograph showing the
cytoskeleton
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4.3 Eukaryotic Cells
Cytoskeleton
• Cytoskeleton proteins work in these
following ways to change cell shapes, make
cell movements, or move organelles
• By shortening, lengthening, or sliding past each other
• Requires energy (ATP)
• May act as railroad tracks for motor proteins moving
molecules or organelles within the cell
• May be pulled by motor proteins (as in muscle cells)
Cytoskeleton - Animation
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4.3 Eukaryotic Cells
Cytoskeleton
• Cytoskeleton proteins (continued)
• Participate in cell division
• Guide chromosome movements (microtubule)
• Pinch dividing cell into two daughter cells (actin)
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4.3 Eukaryotic Cells
Cytoskeleton
• Cilia and flagella move the cell through
fluid or move fluid past the cell
• Flagella and cilia consist of microtubules.
• Flagella are longer than cilia, and cells with
flagella usually have only one or two
• Ciliated cells line such diverse structures as the
gills of oysters, the oviducts of female mammals,
and the respiratory tracts of land vertebrates
• Most animal sperm rely on flagella for movement
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Figure 4-8
cilia lining
trachea
protein
sidearms
fused
microtubule
pair
(b) Cilia
central pair of
microtubules
TEM showing crosssection
flagellum of
human sperm
plasma
membrane
basal body (extends
into cytoplasm)
(a) Internal structure of cilia and flagella
© 2017 Pearson Education, Inc.
(c) Flagellum
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4.3 Eukaryotic Cells
Cytoplasm – Endomembrane system
• The eukaryotic cytoplasm contains
membranes that form the endomembrane
system
• The endomembrane system segregates
molecules from the surrounding cytosol to
ensure the orderly occurrences of biochemical
processes
• The endomembrane system includes the
nuclear envelope, endoplasmic reticulum,
Golgi apparatus, lysosomes, vesicles, and
vacuoles
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4.3 Eukaryotic Cells
Cytoplasm – Endomembrane system
Endoplasmic Reticulum
• The endoplasmic reticulum forms
membrane-enclosed channels within the
cytoplasm (animation to 3:10)
• The endoplasmic reticulum (ER) is a series of
interconnected membranes that form a labyrinth
of flattened sacs and channels within the
cytoplasm
• All the proteins and phospholipids of cell
membranes are synthesized in the ER
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Figure 4-11 Endoplasmic reticulum
ribosomes
smooth ER
rough ER
rough
ER
smooth ER
vesicles
Endoplasmic reticulum may be
rough or smooth
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Smooth and
rough ER
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Figure 4-10 Ribosomes
ribosome
polyribosome
mRNA
growing
protein
amino acid
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4.3 Eukaryotic Cells
Cytoplasm – Endomembrane system
Endoplasmic Reticulum
• Rough endoplasmic reticulum
• studded with ribosomes that synthesize proteins
• Fold proteins in ER channels.
• Produce cell membrane (phospholipids) and
membrane proteins
• Smooth endoplasmic reticulum
• has no ribosomes,
• synthesizes lipids - such as membranes and
steroid hormones (depends on cell types).
• Break down harmful substances, detoxifies
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drugs.
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Oncocytic Adrenocortical Carcinoma
Prominent nucleoli, perinuclear rough endoplasmic reticulum,
numerous cytoplasmic mitochondria, and lipid droplets are
noted ultrastructurally.
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RER disease
Transmission electron microscopy
(TEM) of cultured fibroblasts in a
patient (right panels) and a healthy
control individual (left panels) revealed
dilated cisterns of the rough
endoplasmic reticulum (RER, upper
panels) and decreased number of free
ribosomes (red circles, lower panels) in
the patient cells.
4.3 Eukaryotic Cells
Cytoplasm – Endomembrane system
Golgi Apparatus
• The Golgi apparatus modifies, sorts, and
packages important molecules
• The Golgi apparatus modifies molecules,
especially, adding a carbohydrate group to
proteins to make glycoproteins
• It sorts and packages (UPS distribution
center) the finished proteins and lipids received
from the ER into vesicles that are then
transported to other parts of the cell (within) or to
the plasma membrane for export
Animation (3:10-3:50)
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Figure 4-13
Protein-carrying
vesicles from the ER
merge with the Golgi
apparatus.
Golgi
apparatus
© 2017 Pearson Education, Inc.
Vesicles carrying
modified protein leave
the Golgi apparatus.
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4.3 Eukaryotic Cells
Cytoplasm – Endomembrane system
Golgi Apparatus
• Secreted proteins are modified as they
move through the cell
• Secreted proteins, like antibodies, are made in
the rough ER, travel through Golgi, and then are
exported through the plasma membrane
• Antibodies are glycoproteins produced by white blood
cells that attach to foreign invaders to destroy them
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4.3 Eukaryotic Cells
Cytoplasm – Endomembrane system
Vesicles
• Vesicles are membranous sacs
transporting molecules to the various
regions of the membrane system
• Exocytosis is the process whereby vesicles fuse
with the plasma membrane as they export their
contents outside the cell
• Endocytosis is the process whereby the plasma
membrane extends and surrounds material just
outside the cell, fuses, and then pinches off to
form a vesicle inside the cell
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Figure 4-13 A protein is manufactured and exported
(interstitial fluid)
Vesicles merge with the
plasma membrane and
release antibodies into the
interstitial fluid
(cytosol)
Completed glycoprotein
antibodies are packaged
into vesicles on the opposite
side of the Golgi apparatus
vesicles
Golgi apparatus
Vesicles fuse with the
Golgi apparatus, and
carbohydrates are added
as the protein passes
through the compartments
The protein is
packaged into vesicles
and travels to the Golgi
apparatus
forming
vesicle
Antibody protein is
synthesized on ribosomes
and is transported into
channels of the rough ER
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4.3 Eukaryotic Cells
Cytoplasm – Endomembrane system
Lysosome
• Lysosomes serve as the cell’s
digestive/waste treatment system
• Digestive proteins are made in the rough ER,
travel through the Golgi, and are packaged in
membrane-enclosed vesicles as lysosomes
• A lysosome fuses with a food vacuole and
digests food into basic nutrients
• Absent in most plants (vacuole instead)
Animation (3:50 – 4:20)
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Figure 4-14 Formation and function of lysosomes and food vacuoles via the endomembrane system
(interstitial fluid)
(cytosol)
food
food
vacuoles
A lysosome fuses
with a food vacuole,
and the enzymes
digest the food
The enzymes
are delivered to
the lysosome in
vesicles
lysosome
The Golgi
apparatus modifies
the enzymes for
export to the
lysosomes
Golgi apparatus
digestive
enzymes
The enzymes
are packaged into
vesicles and travel to
the Golgi apparatus
Digestive
enzymes are
synthesized on
ribosomes and
travel through
the rough ER
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Tay-Sachs Disease or Lysosomal
storage disease
This EM photo shows numerous membrane bound myelin figures. These myelin figures are
composed of whorls of membranes enclosed within the lysosomes
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4.3 Eukaryotic Cells
Cytoplasm – Endomembrane system
Vacuole (plant only)
• Vacuoles serve many functions, including
water regulation, storage, and support
• Many freshwater organisms possess contractile
vacuoles composed of collecting ducts, a central
reservoir, and a tube leading to a pore in the
plasma membrane that carries excess water out
of the organism
• Cellular energy is used to pump salts from the
cytoplasm of the protist into collecting ducts
• A full contractile vacuole contracts, squirting
water out through a pore in the plasma
membrane
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4.3 Eukaryotic Cells
Cytoplasm – Endomembrane system
Vacuole (plant only)
• Plant cells have central vacuoles
• A large central vacuole occupies three-quarters
or more of the volume of most mature plant cells
and has several functions
• Central vacuoles provide support for plant cells
• Turgor pressure (water pressure), within the vacuole,
pushes the fluid portion of the cytoplasm up against
the cell wall
• To maintain water balance
• To store hazardous wastes, nutrients, or pigments
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4.3 Eukaryotic Cells
Energy related organelles
• Some eukaryotic cells are supported by
cell walls
• The outer surfaces of plants, fungi, and some
protists are covered with nonliving, relatively stiff
coatings called cell walls
• Plant cell walls are composed of cellulose and
other polysaccharides
• Fungal cell walls are made of polysaccharides
and chitin
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4.3 Eukaryotic Cells
Energy related organelles
• Mitochondria extract energy from food
molecules, and chloroplasts capture solar
energy (photosynthesis)
• All eukaryotic cells have mitochondria that capture
energy stored in sugar by producing high-energy
ATP molecules
• Plant cells have chloroplasts, which can capture
energy from sunlight and store it in sugar molecules
• Biologists believe that both mitochondria and
chloroplasts evolved from prokaryotic bacteria that
became incorporated into the cytoplasm of other
prokaryotic cells (endosymbiont hypothesis)
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4.3 Eukaryotic Cells
Energy related organelles
• The endosymbiont hypothesis
• Both mitochondria and chloroplasts are about the
size
of prokaryotic cells (1–5 micrometers in
diameter)
• Both have a double membrane, the outer
possibly coming from the host cell and the inner
from the
guest cell
• Both have enzymes to synthesize ATP
• Both possess DNA and ribosomes
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Figure 4-16 A mitochondrion
outer
membrane
inner
membrane
intermembrane
space
matrix
cristae
0.1 micrometer
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Figure 4-17 A chloroplast
outer membrane
inner membrane
stroma
thylakoid
channel
interconnecting
thylakoids
granum
(stack of thylakoids)
1 micrometer
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4.3 Eukaryotic Cells
Energy related organelles
• Plastids
• Synthesize and/or store pigments or food
molecules
•
•
•
•
Fruit color
Flower color
Starch
Lipids
• Only found in plants and photosynthetic protists
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Figure 4-19
plastid
starch
globules
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4.4 Major Features of Prokaryotic Cells
• Prokaryotic cells are small (<5 µm long)
and possess specialized surface features
• Prokaryotic cells have fewer specialized
structures within their cytoplasm
• They usually have a stiff cell wall
• Prokaryotic cells can take several shapes
• Rod-shaped bacilli
• Spiral-shaped spirilla
• Spherical cocci
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Figure 4-3a
pili
chromosome (within
the nucleoid region)
ribosomes
plasmid (DNA)
prokaryotic
flagellum
cytoplasm
plasma membrane
capsule or
slime layer
food
granule
cell wall
(a) Generalized prokaryotic cell (bacillus)
© 2017 Pearson Education, Inc.
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4.4 Prokaryotic Cells
Nucleoid
• In the central region of the cell is an area
called the nucleoid, which is separate
from the cytoplasm
• Within the nucleoid is a single, circular
chromosome of DNA
• Small rings of DNA (plasmids) are located in the
cytoplasm
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4.4 Prokaryotic Cells
Cell surface
• All bacteria
• have cell wall, composed of peptidoglycan
(sugars and small peptides)
• polysaccharide coatings called capsules and
slime layers (glycocalyx) outside their cells
• Capsules and slime layers are similar except capsules are
harder to remove
• assist in the formation of adhesive films
• Examples include tooth decay, diarrhea, and urinary tract
infections
• Both protect bacteria and keep them from drying out
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4.4 Prokaryotic Cells
Pili
• Pili (meaning hairs) are surface protein
projections of the cell walls in some
bacteria that further enhance adhesion
• Attachment pili are short and abundant; they help
bacteria adhere to structures
• Sex pili – exchange genetic materials via
plasmids
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4.4 Prokaryotic Cells
No membrane bound organelles
• Prokaryotic cells have no nuclear
membrane or membrane-bound
organelles present
• Some have internal membranes used to
capture light
• The cytoplasm may contain food granules
and ribosomes, the latter with a function
similar to that of ribosomes in eukaryotic
cells
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Table 4-1
Endomembrane
System
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Lab- Microscope
How to use a microscope
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Microscopy Today: Compound Light Microscope
• Light passed through specimen
• Focused by glass lenses
• Image formed on human retina
• Max magnification about 1000X
• Resolves objects separated by 0.2 m,
500X better than human eye
How to use a microscope
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Determining the size of objects
• Total magnification = ocular lens x
objective lens
• Use an object of known dimension (e.g.
stage micrometer) to calibrate the ocular
micrometer at lower power (40x or 100x).
Ruler
<1
mm>
At 40x
I mm = 1000 µm = 42 O.U.
1 O.U. = 1000 µm/42= 23.8 µm
If you switch to 100x
1 O.U. = 23.8 *(40/100)= 9.5 µm
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Onion skin cells/human
epithelial cell
1. Draw a picture of your
observation.
2. Label your drawings –
organelles.
3. Measure the width and length
of a cell in “ocular units”
4. Convert ocular unit into µm
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