Chapter 7
Cellular Structure and Function
Chapter 7.3
Cell Structures and Organelles
The Cell is a Factory for Making
PROTEINS!!
Cell Organelles
Cell Part
Function
Cytoplasm
Semifluid material that surrounds the organelles and
provides a place for chemical reactions to take place.
Cytoskeleton
A network of long, thin protein fibers that form a
framework and support system for the cell; anchors all the
organelles
Nucleus
Control center of the cell; contains the cell’s DNA;
surrounded by nuclear membrane (envelope)
Ribosomes
Produces proteins
Nucleolus
Produces ribosomes
Endoplasmic reticulum
Folded membrane system that is the site for protein and
lipid production
Smooth ER
Area with no ribosomes attached; place where many
carbohydrates and lipids are produced
Rough ER
Ribosomes are attached and produce proteins
Cell Organelles
Cell Part
Function
Golgi Apparatus
Flattened membranes that modified, sorts, and packages
proteins
Vacuoles
Temporary storage for the cell; used to store food, enzymes, and
other materials needed for the cell
Lysosomes
Structure containing enzymes used to digest waste
Centrioles
Used in cell reproduction
Mitochondria
Produce energy by breaking down sugars
Chloroplasts
Capture light energy and convert it to chemical energy (food);
found in plant cells
Cell wall
Thick, rigid fibers that surround the plasma membrane and
protects the cell
Cilia and Flagella
Used for cell movement in some eukaryotic cells
Cytoplasm and Cytoskeleton
Cytoplasm
Semifluid material that surrounds the organelles and
provides a place for chemical reactions to take place.
Cytoskeleton
A network of long, thin protein fibers that form a
framework and support system for the cell; anchors all the
organelles
Nucleus and Nucleolus
Nucleus
Control center of the cell; contains the cell’s DNA;
surrounded by nuclear membrane (envelope)
Nucleolus
Produces ribosomes
Ribosomes
Ribosomes
Produces proteins
Smooth and Rough
Endoplasmic Reticulum
Endoplasmic reticulum
Folded membrane system that is the site for protein and
lipid production
Smooth ER
Area with no ribosomes attached; place where many
carbohydrates and lipids are produced
Rough ER
Ribosomes are attached and produce proteins
Golgi Apparatus
Golgi Apparatus
Flattened membranes that modified, sorts, and packages
proteins
Vacuole
Animal Cell
Plant Cell
Vacuoles
Temporary storage for the cell; used to store food, enzymes,
and other materials needed for the cell
Lysosomes
Lysosomes
Structure containing enzymes used to digest waste
Centrioles
Centrioles
Used in cell reproduction
Mitochondria
Mitochondria
Produce energy by breaking down sugars
Chloroplasts
Chloroplasts
Capture light energy and convert it to chemical energy (food);
found in plant cells
Cell Wall
Cell wall
Thick, rigid fibers that surround the plasma membrane and
protects the cell
Cilia and Flagella
Cilia and Flagella
Used for cell movement in some eukaryotic cells
p. 199
Chapter 7.4
Cellular Transport
Predict
• Food coloring
demonstration
– Drops of red and blue
food coloring are added
to opposite ends of a
container of water.
• Hypothesize:
– What will happen when
the food colorings are
added?
– What will happen after
5 minutes?
Observation & Explanation
• Observe:
– What happened to our food colorings?
• Explain:
– How can this result be explained?
Figure 7.20 © Glencoe-McGraw Hill (2007)
Diffusion
• Substances dissolved in water (solutes) move
constantly in random motion; this is call
Brownian Motion
• Causes diffusion
– net movement of particles from an area where
there are many particles of the substance (high
concentration) to an area where there are few
particles of the substance (low concentration)
• There are two components of solution:
– Solvent – a substance in which another substance
is dissolved
– Solute – the substance that is dissolved
Diffusion
• Movement of substances from high concentration
to low concentration
• Caused by the RANDOM movement of particles
• Requires no energy input!
http://www.indiana.edu/~phys215/lecture/lecnotes/lecgraphics/diffusion.gif
http://www.indiana.edu/~phys215/lecture/lecnotes/lecgraphics/diffusion2.gif
• Interactive Diffusion Activity:
http://www.wisc-online.com/objects/ViewObject.aspx?ID=AP1903
Dynamic Equilibrium
• Once a uniform purple color is
reached, the food coloring
particles continue to move
randomly.
• However, at some point, all
particles of a substance (in this
case food coloring) will be as
spread out as they can and there
will no longer be areas of high
and low concentration.
• When this occurs, dynamic
equilibrium has been reached.
Diffusion in Cells
Factors that Affect Diffusion
• Three main factors affect the
rate (speed) of diffusion:
– Concentration of the diffusing particles
– Temperature
– Pressure
• If any of these three increases, the diffusion
rate will increase. Why?
Facilitated Diffusion
A. Water can pass easily through the plasma
membrane – most substances cannot
B. In facilitated diffusion, special transport
proteins move ions and small molecules across
the plasma membrane
Transport Processes
• Passive transport – movement of a
substance across the plasma
membrane without the use of the
cell’s energy.
• Active transport – requires the use
of the cell’s energy to move
substances into or out of a cell
across the cell membrane.
No Energy
Required
Requires Energy
Cellular Transport Videos
http://www.youtube.com/watch?v=1ZFqOvxXg9
M&feature=related
Osmosis is the
DIFFUSION OF WATER
Osmosis
• The diffusion of water across a selectively
permeable membrane.
Figure 7.22 © Glencoe-McGraw Hill (2007)
– Cells must regulate this in order to maintain
homeostasis.
– One of three
situations exists.
• http://www.stolaf.edu/people/giannini/flasha
nimat/transport/osmosis.swf
• http://www.youtube.com/watch?v=sdiJtDRJQ
Ec
Isotonic Solution
• Cell is in a solution that has the same
concentration of water and solutes
 Iso – Greek meaning “equal”
 cell is in dynamic equilibrium
with environment
 Water enters and leaves the
cell at the same rate.
Figure 7.23 © Glencoe-McGraw Hill (2007)
Hypotonic Solution
• Cell is in a solution that has a lower
concentration of solute than the cell
 hypo – Greek meaning “under”
 Net movement of water is into
the cell
 Causes osmotic pressure
 In animals – cell could burst
 In plants, cell wall prevents
bursting; cell becomes firmer
Figure 7.24 © Glencoe-McGraw Hill (2007)
Hypertonic Solution
• Cell is in a solution that has a higher
concentration of solute than the cell.
 hyper – Greek meaning “above”
 Net movement of water is out
of the cell
 Results:
 In animals – cells shrivel
 In plants, central vacuole pulls
away from cell wall; plant wilts
Figure 7.25 © Glencoe-McGraw Hill (2007)
Red Blood Cells – A Comparison
• Is your blood pure
water?
• What would happen
to your red blood
cells if pure water
were to be injected
into your blood
stream?
Osmosis Examples
Example
Pickles are made by immersing cucumbers in a concentrated
saltwater solution.
Spraying plants with a solution that contains too high a concentration
of fertilizer might cause them to dry out and die.
Patients undergoing surgery are given 0.9% saline (saltwater)
solution.
One of the oldest methods of preserving food is to pack them in
saline solutions, which kill the bacteria that cause foods to spoil.
Organisms that live in seawater have specialized mechanisms that
prevent them from becoming dehydrated.
Florists store fresh flowers in cold water to help the flowers keep
their original appearance.
Solution