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Chapter 7 Notes
Cell Structure & Function
Section 7-1 ~ Life is Cellular
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A. The Discovery of the Cell (pg.169)
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1. Early Microscopes: (Tell Who?
What Discovered or Used?
When?)
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a. In 1665, an Englishman Robert Hooke used an
early compound microscope to look at a
thin slice of cork. Used the term “cell”.
b. In Holland about 1674, Anton van Leewenhoek
used a single-lens microscope to observe
pond water and found tiny living organisms…
even in the water he drank.
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2. The Cell Theory (pg. 170) ~

a.
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b. The Cell Theory States:
1838, German botanist Matthias Schleiden
Concluded that all plants were made of cells.
In 1839, German Theodor Schwann stated
all animals were made of cells.
In 1855, German Rudolf Virchow concluded that new
cells could be produced only from existing cells.
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1. All living things are composed of cells.
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2. Cells are the basic units of structure & function
In living things.
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3.
New cells are produced from existing cells.
B. Exploring the Cell
Microscopes are
pg. 170-171
always improving.
(What is the main idea of this passage?)
1.
Light Microscopy
{How does this
work? Advantages & Disadvantages?}
Light microscopes use light in order to magnify images.
Some light microscopes uses laser beams to scan cells
for 3 dimensional pictures, produce movies of cells as
they grow, divide & develop. Light has limitations with
resolution.
Light Microscopy
/ black widow spider
Light Microscopy / black widow spider eyes
Light Microscopy / diatom
Light Microscopy / radiolaria x10
Kingdom: Protist
Scientific Name: Amoeba proteus
Image Courtesy of: Joanne Whallon
Image Width: 30 microns
Image Technology: Laser Scanning
Confocal
Kingdom: Fungus
Scientific Name: Saccharomyces cereviceae
Image Courtesy of: Whallon, Joanne
Image Width: 24 microns
Image Technology: Laser Scanning Confocal Microscopy
Scanning Electron
Microscopes (SEMs)
{How does this work? Advantages & Disadvantages?}
Electon microscopes use a pencil like beam
of electrons to view the surface of
specimens. Can view details of a specimen
1000 times smaller but the specimen must
be in a vacuum and only non-living.
Electron micrograph of a mitochondrion in a section from bat pancreas.
The mosquito's head is mostly eye. The eyes of most insects are compound eyes, made up
of many tiny lenses. Each lens sees a slightly different picture, making up a mosaic of the
object it is looking at. This type of vision is very efficient at noticing very slight motions
such as another insect trying to sneak up on it
Flies use their feet for many purposes. The claws can grab
to hold on. The small hairs will adhere to smooth surfaces
through surface tension. Other hairs are sensory organs,
allowing flies to taste with their feet.
Many types of worms have become specialized to live as parasites
inside other organisms. This spiny-headed worm uses the spines
on its head to attach to the small intestine of a fish. Without a
mouth, the worm absorbs nutrients from the fish through its body
wall.
Diatoms are tiny single celled plants that live inside a hard shell. They
occur in great quantities both in salt and fresh water. When the plant
dies, the shell sinks to the bottom. Over time, large quantities of these
shells accumulate. They can be collected and used as diatomaceous
earth in swimming pool filters. The shells allow water to pass through
but trap any small dirt particles.
This cross section of a fern leaf allows us a view of
the inside of its cells. The electron microscope
reveals many of the cells' structural details not
noticeable with the light microscope.
This beautiful vase-like structure is the skeleton of a
single-celled organism called a radiolarian. Radiolarians
live in large quantities as part of the ocean's plankton.
When the radiolarian dies, it's shell sinks to the bottom.
After millions of years of radiolarian shells "raining
down" on the sea floor, they accumulate in great
quantities. Much of the sea floor of the deep oceans are
covered in this radiolarian "ooze".
SEM ~ Insect antenna
SEM ~ Bee head
SEM ~ Bee Face
SEM ~ dragonfly head
SEM ~ plant pollen
SEM ~ stem
SEM~ wood
SEM~ Leaf
SEM ~ Tick (parasite)
3.
Transmission Electron Microscopes
(TEMs {How does this work? Advantages & Disadvantages?}
Electrons are used to view objects.
Scientists must first cut samples into
ultra thin slices for electrons to pass
through. Therefore only non-living
specimens may be used.
TEM images- Cells / cultured cells
TEM images- Cells / freeze etch yeast
TEM images- Cells / mitochondria
TEM images- Cells / muscle l.s
TEM images- Cells / nerve cell bundle
TEM images- Plant cells / root cell
Scanning Probe Microscopes
In the 1990’s a microscope that
traces the surface of samples with a
probe was perfected. Now we can
observe single atoms.
They can operate in ordinary
air & in solutions.
C. Prokaryotes & Eukaryotes –
pg.172-173
Organism
Definition
Description
Activities
Prokaryote
Genetic material
that is NOT
contained in a
nucleus.
Smaller & less
complex than
eukaryotic cells.
Grow,
reproduce,
respond &
sometimes move
Eukaryote
Contain a
nucleus in which
their genetic
material is
separated from
the rest of the
cell
Larger & more
complex with
dozens of
structures &
membranes.
Great Variety &
carry out
activities
associated with
living things.
Difference between Prokayote &
Eukaryotes is that…
Prokaryotes do NOT have a nucleus &
Eukaryotes DO
III. 7-3 Cell Boundaries pg. 182
~All cells are surrounded by a thin, flexible barrier known as a cell membrane
~Many cells also produce a strong supporting layer around the membrane known
as a cell wall.

A. Cell Membrane



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1. Regulates what enters & leaves the cell
2. Provides protection & support
3.Composed of a double-layered sheet called a lipid
bilayer & contains protein molecules with carbohydrate
molecules attached.
4. These proteins form channels and pumps that help to
move material across the cell membrane. Many of the
carbohydrates act like chemical identification cards that
allows cells to identify one another.
Why would cells need to identify each other?

B. Cell Walls pg. 183
1. Present in many organisms, including
plants, algae, fungi & many prokaryotes.
 2. Lie outside the cell membrane & made of
cellulose; a tough carbohydrate fiber
 3. The main function is to provide support &
protection for the cell
 4. Made from fibers of carbohydrate &
protein that are produced from within the
cell.


C. Diffusion Through Cell Boundaries
 One of the most important functions is to regulate
the movement of dissolved molecules from the
liquid on one side of the membrane to the liquid on
the other side.


2. Diffusion is the process of particles moving from an area where they
are more concentrated to an area where they are less
concentrated. When the concentration of the solute is the same
throughout a solution = equilibrium.
(Because diffusion depends upon random particle movements,
substances diffuse across membranes without requiring the cell to use
energy. )
D. Osmosis is the diffusion of water through a
selectively permeable membrane pg. 185


1. How Osmosis Works - Water will move from where it is
more concentrated to where it is less concentrated until
equilibrium is reached.

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When equilibrium = isotonic
In the beginning, more concentration sugar side = hypertonic
(above strength)
The diluted or less sugar concentration side = hypotonic (below
strength)
2. Osmotic Pressure is the pressure on the hypertonic side of
a membrane
http://programs.northlandcollege.edu/biology/Biology1111/animations/transport1.html
What will happen?
Why?
What do you NOW know about
the selectively permeable membrane?

E. Facilitated Diffusion (pg. 187) Facilitate = HELP

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1. Happens when a cell membrane’s protein channel helps the diffusion of
particles across. Occurs when a molecule that seems too large to pass through a
cell membrane is able to get across.
2. Example: Red blood cells have an internal channel that allows glucose to pass
through.
3. A net movement of molecules across a cell membrane will occur only if there is
a higher concentration of that particular molecule on one side than on the other
side. This movement does not require energy FROM THE CELL.
F. Active Transport pg. 188 when a cell moves , materials against a
concentration – in the opposite direction & requires energy & carrier
proteins within the membrane.

1. Molecular Transport is when small molecules and ions
are carried across the membrane by protein pumps; used
to move calcium, potassium & sodium ions.

A considerable amount of our daily energy is devoted to this
active transport.

2. Endocytosis & Exocytosis

A. Endocytosis is the process of taking materials into
the cell by means of infoldings or pockets of cell
membrane which breaks loose and forms a vacuole.

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Phagocytosis is “cell eating” and when food is taken into a
vacuole.
Pinocytosis is “cell drinking” when liquids are taken into
the cell within a vacuole
B. Exocytosis is the release of large amounts of
materials from the cell by vacuole fusing to the cell
membrane and forcing the contents out of the cell.
 C. The removal of water by means of a contractile
vacuole is one example of exocytosis.

For example, this electron micrograph is showing the process of exocytosis .
The process begins by fusion of the membranes at the peripheral pole of the granule.
Then an opening is created which widens to look like an omicron figure.
This opening allows the granular material to be released. The membrane is now part
of the plasma membrane and any proteins carried with it can be incorporated into
the plasma membrane.
Exocytosis
Endocytosis
IV.
7-4 The Diversity of Cellular Life
The diversity of life is so great that you might have to
remind yourself that all living things are:
~composed of cells
~use the same basic chemistry
~follow the same genetic code
~contain the same kinds of organelles

A. Unicellular Organisms pg. 190

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1. Also called single celled
2. They grow, respond to the environment, transform
energy & reproduce.
3. In terms of their numbers, unicellular organisms
dominate life of Earth.
Bacteria Cell
Scanning electron micrograph of the common soil
bacteria Pseudomonas aeruginosa. These bacteria are
actively motile in aqueous environments.
The one-celled organism
amoeba proteus
Volvox
http://protist.i.hosei.ac.jp/PDB5/PCD0044/htmls/04.html
Algae

B. Multicellular Organisms pg. 190
 1. Multi Cellular means many celled and
there is great variety among these
organisms.
2. All depend on communication & cooperation
among specialized cells – cells created for a
particular function
 3.Specialized Animal Cells
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Red blood cells – transport oxygen throughout the body
Pancreatic cells – produce compounds such as insulin that the body
needs.
Muscle cells - contract & relax to move parts of the body
4. Specialized Plant Cells

Guard cells – control the opening & closing of stomata on the
underside of leaves.
These cells come off the stratified squamous epithelial tissue on
the inner surface of the cheek. These cells show the irregular,
flat shape characteristic of typical "squamous cells." The
nucleus (A) is centrally located, the cell membrane (C) is very
thin, and the cell is filled with cytoplasm (B).
A human red blood cell
The villi of the small intestine
are lined by a single layer
of columnar cells (A) – thus
the name simple columnar
epithelium. Note these cells
are not as wide as they are
tall with the darkly stained
nuclei (B) located at the base
of the cells. The cell membranes
(C) are very thin but easily
identified.
Locations: lining most of the
digestive tract
Function: protection, secretion
and absorption

C. Levels of Organization are individual cells,
tissues, organs, & organ systems .
 1. Tissues

Similar cells grouped into units & these cells perform a particular
function.
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2. Organs
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Many groups of tissues working together form an organ.
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Ex: A collection of cells that produce digestive Enzymes in the pancreas
make up one kind of tissue
Most animals have 4 main types of tissue: muscle, epithelial, nervous &
connective
Each muscle in your body is an individual organ because within your muscle
there is much more than muscle tissue…nerves tissues and connective
tissues are there also.
3. Organ Systems

A group of organs working together to perform a specific function

Ex: Circulatory system, reproductive system, digestive system