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Chapter 5
Cell Structure and
Function
5-1 The Cell Theory
 How
did van leeuwenhoek, Hooke,
Schleiden, Schwann, and Virchow
contribute to the development of the
cell theory?
 What
are the parts of the cell theory?
All Living things are made of cells!
 Cell-
the basic unit of structure and
function in living things
 First
found under lenses in
microscopes
 Lets
talk about how
History of the cell
 First
lenses were used in Europe
hundreds of years ago for cloth
quality.
 They
then combined lenses together
to see better.
http://www.bombayharbor.com/co
mpany/62262/product.html
In
1600’s two important inventions!
– What were they?
The
telescope – For far away
http://www.robinsdocksideshop
.com/telescopes2.htm
The
Microscope – small
objects in nature visible
http://www.olympusmicro.com/primer/anatomy/introduction.html
Anton van Leeuwenhoek (LAYVuhn-hook)
 Person
given credit for making the
first microscope
 Could
see tiny organisms whose
world was a drop of water
 Observed
them in pond water and
then made drawings
On to England with Robert Hooke
 Used
one of his microscopes to look
at pieces of cork, wood, and stems
 Noticed
 Why
thousands of tiny chambers
did he call them cells?
http://science-of-aging.healthaliciousness.com/timelines/hooke-history-celldiscovery.php
 Was
he looking at living or non-living
cells?
 Why
was it significant?
The next 200 years
 Scientists
in plants
found they were not only
 1833-
Robert Brown observed that
any cells had a dark structure near
the center (What do we call this
now)?
http://www.helloquizzy.com/quizzy/results?quizzyid=936650768789608524&resultid=3
1838-
Matthias Schleiden says, “all
plant were made of cells.”
1839-
Theodor Schwann says, “all
animals were made out of cells.”
Germany
1855-
Rudolf Virchow “New cells
could be produced from the division
of old cells.”
The Cell Theory

Three parts:
– 1. All living things are composed of cells
– 2. Cells are the basic units of structure and
function in living things
– All cells come from preexisting cells
– Cell theory video!
Picture take from: http://pearsonprophoto.com/pictures-of-the-celltheory
5-2 Cell Structure
 What
are the functions of the three
basic structures of most cells?
 How
do prokaryotes and eukaryotes
differ?
 Cell
Video!
Most cells have three common
structures
 The
Cell membrane- outer boundary
of the cell
 The
 The
Nucleus – control center
Cytoplasm – material between
the cell membrane and the nucleus
Cell Membrane
 Regulates
what enters and leaves the
cell. Also, aids in the protection and
support of the cell.
 Think
Walls in
House
 What
process do you think takes
place in the cell membrane?
– Communicate with other cells
– Take in food and water
– And eliminate wastes
 Many
molecules make it up but the
most important are lipids.
A
lipid bilayer forms the cell
membrane
Cell Membrane
Gives
a flexible structure,
strong barrier between the
cell and its surroundings
Most
have proteins embedded
in lipid bilayer.
So
many molecules that they
call cell membrane mosaic
Picture From: http://en.wikibooks.org/wiki/Structural_Biochemistry/Lipids/Lipid_Bilayer
Some
proteins form channels or
pumps which help move material
Carbohydrates
act as chemical I.D.
cards, it allows individual cells to
identify each other.
Cell
Membrane
Video
Picture From: http://php.med.unsw.edu.au/cellbiology/index.php?title=Cell_Membranes_and_Compartments
Cell Wall
 Cell
Wall-Strong supporting layer around
the cell membrane in plants, algae, and
some bacteria
 Lie
outside the cell membrane
 Allows
water, oxygen, and carbon dioxide
to pass through pretty easily.
 Why
is that important???
•Primary Cell Wallcellulose (elasticity)
•Secondary Cell
Wall-Cellulose and
lignin (Wood)
Picture from: http://library.thinkquest.org/C004535/cell_wall.html
Nucleus
 Nucleus-
structure that contains the cell’s
genetic material (DNA) and controls the
cell’s activities
 Eukaryotes-organisms
nuclei
 Prokaryotes-organisms
nuclei
 It’s
whose cells contain
whose cells lack
Greek “pro” = before “eu” = true
 Prokaryotes evolved before the nucleus
Nucleus
Control
center of the cell.
Picture from: http://en.wikipedia.org/wiki/Cell_nucleus
What
does the nucleus contain?
– DNA
What
membrane surrounds the
nucleus?
– Nuclear envelope
Nuclear
envelope-layer of two
membranes that surrounds the
nucleus of a cell
What
does the nuclear envelope do?
– Allows material to move in and out of nucleus
Nucleolus-small,
dense region within
most nuclei in which ribosomes are
made.
Ribosomes
proteins
aid in the production of
Chromosomes
 What
is a chromosome and what does
it form from?
– Threadlike structure within the nucleus
containing the genetic information that is
passed from one generation of cells to the
next. Forms from chromatin
 What
do chromosomes contain?
– Genetic material
Cytoplasm
Can
divide the Eukaryotic cell into
two major parts: Nucleus and
cytoplasm
Cytoplasm-material
inside the cell
membrane-not including the nucleus
These
two structures work
together to create life
picture from: http://www.stephsnature.com/lifescience/cytoplasm.htm
5-3 Cytoplasmic organelles
 The
structures in the cytoplasm are
called organelles
 Organelles-a
tiny structure that
performs a specialized function in the
cell
 Each
has a special job that helps
maintain the cell’s life
Picture from: http://dbscience5.wikispaces.com/Bas
Mitochondria and chloroplasts
Power Stations
 All
living things require energy.
Where do we get these from?
 Sun
 The
or food substances
mitochondrion and the
chloroplast are the key organelles
that change energy from one form to
another.
 Mitochondria-change
the chemical
energy stored in food into
compounds that the cell can use
 Chloroplasts-trap
the energy of
sunlight and convert it into chemical
energy.
 What
organisms are chloroplasts
found in?
Picture from: http://biology.about.com/od/cellanatomy/ss/mitochondria.htm
Power House of the Cell!!!!!!!!!!!!!
Picture from: http://en.wikipedia.org/wiki/Chloroplast
Ribosomes: Protein Factories
 Ribosomes-are
the structures in
which proteins are made
 Cells
are crowded with them if they
are creating proteins
 They
are some of the smallest
organelles 25 nanometers (1 billionth
of a meter
Ribosomes
Picture from: http://en.wikipedia.org/wiki/Ribosome
Endoplasmic Reticulum and Golgi
Apparatus: Manufactures and Shippers
 Endoplasmic
Reticulum (ER)transports materials through the
inside of the cell
 Two
types: Smooth and Rough ER
 Smooth
ER-the walls and sacs look
smooth. Enzymes and chemicals are
stored here
 The
Rough ER is covered with
ribosomes. Why is that?
 It
is responsible for the synthesis of proteins
 The
Rough ER modifies newly made
proteins
Picture from: http://micro.magnet.fsu.edu/cells/endoplasmicreticulum/endoplasmicreticulum.html
 Golgi
apparatus-proteins are
moved here after the ER to be
modified and then sent out of the cell
 It
looks like a flattened stack of
pancakes
Picture from:http://en.wikipedia.org/wiki/Golgi_apparatus
Lysosomes: Cleanup Crews
A
cell can encircle a particle and
bring it into the cell called
endocytosis
 The
particle must now be digested or
broken down by the lysosomes
 Lysosomes-structures
that contain
chemicals and enzymes necessary
for digestion in the cell
 Lysosomes
also break down
organelles that have outlived their
usefulness
 Lysosomes
apparatus
are made by the Golgi
Picture from: http://marionkatiemaggie.blogspot.com/2010/09/lysosomes.html
Vacuoles and Plastids: Storage
Tanks
 Vacuoles-saclike
structure that
store materials such as water, salts,
proteins, and carbs
 Plants
have large central vacuoles
filled with water
 Why
is this important for cells?
Picture From: http://en.wikipedia.org/wiki/Vacuole
 Plastids-plant
organelles that may
take many forms, one of which is the
chlorplast
 Many
are involved in the storage of
food and pigments. Example:
chromoplasts which store pigments
molecules.
 Chromoplasts
tomatoes
= red pigment in
Cytoskeleton: Framework
 Cytoskeleton-composed
of a variety
of filaments and fibers that support
the cell structure and drive the cell
movement
 proteins
that make up the cytoskeleton:
– Microfilaments and microtubules
 What
are microfilaments?
– Threadlike structures made of a protein called
actin
 What
do these help cells do?
– Can help cells move. Ex. amoebas
What
are microtubules?
– Hollow structures made up of
proteins known as tubulins
What
critical role do they play?
– Maintaining cell shape
What
are centrioles?
– Located near the nucleus and help
organize cell division (Not in Plant
cells)
What
do microtubules help build
and what do these structures help
the cell to do?
– Flagella and Cilia. Help cells swim
through liquid
5-4 Movement of Materials Through
the Cell Membrane
 How
do diffusion and osmosis move
materials into and out of cells?
 How
do active and passive transport
differ from each other?
 What
are endocytosis, phagocytosis,
pinocytosis, and exocytosis?
 Each
individual cell is covered in
liquid that was once part of blood (in
us that is).
 This
liquid allows food, oxygen, and
water to move into and out of the
cell
 Several
ways in which materials
enter and leave the cell
Diffusion through cell boundaries
One
main function of the membrane:
to regulate the movement of dissolved
molecules from the liquid on one side
to the liquid on the other side of the
membrane.
Picture from: http://en.wikipedia.org/wiki/Diffusion
Diffusion
 Particles
are always moving in solution
 Diffusion-process
by which molecules
tend to move from an area where they
are more concentrated to an area where
they are less concentrated.
 Equilibrium-
when a concentration of a
solute is the same throughout the solution
What
does this have to do with cell
membrane?
If
a substance is higher on one side of
the cell membrane, and it is able to
move through the membrane. It will
move from the side with a higher
concentration to the side with a lower
concentration.
Diffusion
animation
 Because
diffusion depends upon random
particle movements, substances diffuse
across membranes Without requiring the
cell to use energy!
 Even
at equilibrium particles still move.
 Almost
equal numbers of particles move in
each direction, causes no further change in
concentration
Picture from: http://good50x70.org/2007/gallery/gallery02/
Osmosis
 Some
particles are too large or too
charged too cross the lipid bilayer
Picture From: http://www.biologycorner.com/bio1/diffusion.html
A
membrane is permeable to a substance
if the substance can diffuse across it.
A
membrane is impermeable to a
substance that can’t pass through it.
 Most
membranes are selectively
permeable- Some substances can pass
across them, others can’t
 Water
passes across easily
 Osmosis-
the diffusion of water through
a selectively permeable membrane
Picture From: http://www.occc.edu/biologylabs/documents/cells%20membranes/Osmosis_Definition.htm
How Osmosis Works
Look
on Page 101 Fig. 5-18
In
the left beaker, more sugar
molecules on the left side then on the
right.
Concentration
of water is lower on the
left then on the right.
The
membrane is permeable to the
water and not the sugar. Water can
pass through but sugar can’t
The
means that water will move from
the right to the left of the beaker
High
concentration of water to an area
of low concentration of water. Beaker
on the right.
Water
will move until equilibrium is
reached.
This
means the concentration of water
and sugar is the same on both sides.
Isotonic-When
the concentration of
two solutions is the same
Hypertonic-
When comparing two
solutions, the solution with the greater
concentration of solutes
Hypotonic-
When comparing two
solutions, the solution with the lesser
concentration of solutes.
Diffusion
Animation!!!
Picture From: http://www.biologycorner.com/bio1/diffusion.html
Picture From: http://web.fccj.org/~ethall/2046/ch11/op.htm
Osmotic pressure
 Osmosis
exerts osmotic pressure on the
hypertonic side of the membrane
 Can
cause problems for cell
 The
cell is filled with many molecules,
usually always hypertonic
 Cell
usually has a net movement of fresh
water into the cell if in contact with it
 Could
Cause the cell to burst
 Luckily
most cells do not come in
contact with fresh water
 Example
they are bathed in fluid like
blood which is isotonic
 These
fluids have concentrations that
are about equal in the cell
 Cell
walls prevent cells from expanding.
 Makes
the vulnerable to injury with
increased pressure.
Picture From:
http://legacy.hopkinsville.kctcs.edu/si
tecore/instructors/JasonArnold/VLI/Module%202/m2cellfuncti
onandenergetics/m2cellfunctionand
energetics6.html
Picture From: http://biology.about.com/od/cellularprocesses/ss/diffusion_2.htm
Facilitated Diffusion
 Why
are Large, highly charged, glucose
molecules able to go across the
membrane so easily?
 Cell
 Red
membrane have protein channels
blood cells have internal channel to
allow glucose to pass through it.
Only
glucose can pass through that
channel, and in both directions
The
cell membranes protein facilitates
Facilitated
Diffusion- movement of
specific molecules across cell
membranes through protein channels.
Many,
Many, Many different protein
channels.
Picture From: http://bio1151b.nicerweb.com/Locked/media/ch07/facilitated_diffusion-carrier.html
It
is still diffusion!
Needs
to be a difference of
concentration from one side to the
other
Does
not require energy from
the cell!
Facilitated
Diffusion Animation!!
Picture From: http://www.daviddarling.info/encyclopedia/A/active_transport.html
Active Transport
 Cells
sometimes have to go against the
concentration difference.
 Active
Transport-energy-requiring
process that moves material across a cell
membrane against a concentration
difference.
 This
requires Energy!
 Usually
done by transport pumps or
proteins
 Located
in membrane
 Large
molecules or clumps move by
endocytosis and exocytosis.
 Sometimes
the cell membrane needs to
change shape.
Picture From: http://hyperphysics.phy-astr.gsu.edu/hbase/biology/actran.html
Molecular Transport
Proteins
that act like energy
requiring pumps move molecules
Calcium,
potassium, and sodium ions
are the main things moved
Changing
shape is important
A
large part of a cells energy goes to
active transport
Energy
is needed to keep the
concentration the same on one side
of the membrane even though
diffusion is trying to move it.
Sodium-Potassium
Pump Animation
Endocytosis and Exocytosis
 Large
molecules or clumps of molecules
are able to cross the cell membrane
 Endocytosis-process
by which a cell
takes material into the cell by infolding of
the cell membrane
 The
pocket breaks loose from the cell
membrane and forms a vacuole in the
cytoplasm
Picture From: http://www.psc.edu/science/2007/bardomain/
 Can
be done with large molecules, clumps
of food, and whole cells
 Ex.
Pinocytosis & Phagocytosis.
 Phagocytosis-
Process in which
extensions of cytoplasm surround and
engulf large particles and take them into
the cell.
Amoebas
Requires
use this to get food
a lot of energy = Active
Transport
Picture From: http://www.biofortified.org/2010/03/glowing-phagocytosis/
Pinocytosis-process
by which a cell
takes in liquid from the surrounding
environment
Tiny
pockets form in cell membrane
Exocytosis-process
by which a cell
releases large amounts of material
Vacuole
fuses with membrane and
forces the contents out
Picture From: http://www.psc.edu/science/2007/bardomain/
5-5 Cell Specialization
 Cell
Specialization-cells are often
uniquely suited to perform a
particular function within the
organism.
 Examples:
help move, react to their
environment, and specialized to
make certain products
5-6 Levels of organization
 The
levels of organization in a
multicellular organism include cells,
organs, and organ systems that
make up the organism
http://peer.tamu.edu/curriculum_modules/cell_biology/module_1/index.htm
Tissues
 Cells
are organized in specialized
groups called tissues
 Tissue-a
group of similar cells that
perform similar functions
 The
specialized cells we talked about
earlier make up tissues
 Most
animals have four major types:
– Muscle
– Epithelial
– Nerve
– Connective tissue
http://www.bio.davidson.edu/people/kabernd/BerndCV/Lab/EpithelialInfoWeb/index.html
Organs
 Could
take hundreds of thousands of
cells to make a tissue
 Many
tasks are too complicated to be
done by just one type of tissue
 In
these cases an organ is needed
 Organ-a
group of tissues that work
together to perform a specific
function
 Each
muscle in your body is a
specific organ…Why do they say
that?
A
muscle is made up of muscle,
nerve, and connective tissue
http://okolo.org/2011/01/24/microcosmic-orbit-and-prelude/
Organ systems
 Even
a complex organ is not able to
complete a series of specialized tasks
 Organ
System-a group of organs
that works together to perform a
certain functions
 There
are eleven organ systems in
the body…
http://www.jlhahnconsulting.com/prepsteps1/bioG2.html
 These
levels of organization make
multicellular life possible
 The
specialization is of cells is vital to
living things