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Chapter 3 Cells The Basis of Life
 Environment of the cell
Extracellular environment
*Fluid filled area outside the cell
Intracellular environment
*Fluid filled area inside cell
 Drawings on p.49 fig. 3-1 a and b
A. Extracellular Environment
 Area outside the cell.
 Contains gases, salts,
food particles, and
cellular products which
are materials
synthesized by cell and
released by secretion.
*These cellular
products are proteins,
hormones and vitamins.
Matrix
*Solid
*Provides structural
support
 Intercellular
environment
*Compartment of
Extracellular
environment between
adjacent cells
 In the extracellular
environment, you have
extracellular fluid (ECF)
*This is a syrup like
mixture of water
products and other
substances
2 Types of ECF
1. Plasma
*Located within vessels
*Provides liquid medium for transport of
substances in blood
2. Interstitial fluid
*Located between cells of body
*Provides pathway for substances
going to and from the cells
B. Intracellular Environment
 Protoplasm
 This is where most
internal cell
functions occur.
 Energy production.
 Energy storage.
 Synthesis of new
products.
*Substance of a cell.
Composed of water,
proteins, carbohydrates,
fats, nucleic acids and
electrolytes.
*It is alive when all
materials carry out
activities.
 Characteristics of living
things.
*Organization, growth,
metabolism,
reproduction,
excitability.
3 Parts of Protoplasm
1.Plasma Membrane
(cell membrane)
*Separates inside of cell
(intracellular
environment) from its
outside environment
(extracellular
environment). Contains
intracellular fluid (ICF)
which is a mixture of
water, proteins and
other chemicals.
3 Parts of Protoplasm
2.Cytoplasm
*Thickened gel like
material which
occupies most of the
ICF. This is where
the organelles are.
3 Parts of Protoplasm
3. Nucleus
*Regulates activities
of cell. Lies within
intracellular
environment.
Packet questions pp.35-37 1-29
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Cell Structure and Function
 Common features of
cells are plasma
membrane, cytoplasm
and nucleus which all
work together to provide
cellular functions.
 Size is small and
measured in
micrometers which is 1
millionth of a meter.
25,400 micrometers
equals 1 inch.
 Size varies according to
function of cell.
 Model of a cell.
Drawing p.50 fig.33 Also do 2-3
observing a human
cell.
Plasma Membrane
*Separates intracellular environment from
extracellular environment.
*Regulates movement of materials
between these areas.
*Envelopes cell completely.
*Maintains homeostasis because plasma.
*Membrane regulates materials.
A. Structure
 Lipid bilayer and protein molecules and
a little carbohydrates
 Is less than one millionth of an inch
thick
 Selectively permeable: only allows
certain substances to pass through.
Plasma Membrane
Structure
 Glycoproteins
 Proteins
*Union of proteins and
carbohydrates.
Receptors for
substances that must
distinguish between
different types of cells
like hormones, growth
factors and antibodies.
*Peripheral proteins
attach to outside and
inside of cell surface.
*Integral proteins are
embedded in the lipid
bilayer and extend out.
These proteins form
channels and give the
cell its status of
selectively permeable.
Modifications of Plasma Membrane
1.Microvilli
 Tiny plasma membrane
extensions
 Increase surface area
 More materials cross
over
 In cells which absorb
*cells lining small
intestines
*excretory cells in
kidneys
Modifications
2.Cilia
 Longer
 Contain protein
microtubules for
structure and support
 Do not absorb but keep
things moving
 Cells lining respiratory
tract, to keep mucous
moving
*ciliary action
Modifications
3.Flagella
 1 and long
 Contains protein
microtubules
 Provide propulsion
*sperm cells
 http://pictures.ask.com/r
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B. Functions
 Ways in which materials cross the
plasma membrane
*Based on the energy that is required
1. passive transport
2. active transport
1. Passive Transport
 Powered by kinetic
energy, force which
causes molecules to
move about
randomly.
 Requires no energy
from the cell.
 3 types
i. Diffusion
ii. Osmosis
iii. Filtration
I.Diffusion
*Kinetic energy only
*Molecules move from a
region of higher
concentration to a
region of lower
concentration.
*Movement continues until
equilibrium is reached
*Diffusion moves with a
concentration gradient
*A diffusion in
concentration from one
region to another
 EX. Spray a
freshener in air.
 EX. In body,
movement of
oxygen molecules
from air sacs in
lungs to blood
vessels that
surround air sacs.
Diffusion
 Diffusion through
plasma membrane.
*lipid-soluble solutes
diffuse right in.
*lipid-insoluble solutes
like glucose use
facilitated diffusion with
the integral protein to
get in
Passive Transport
II. Osmosis
 The movement of water
molecules across a
selectively permeable
membrane from a
region of higher water
molecule concentration
to a region of lower
water molecule
concentration (lower
water molecule
concentration means
higher solute
concentration).
 Just like diffusion,
osmosis moves with
a concentration
gradient until
equilibrium is
reached.
Osmosis
 Osmotic pressure is the
force exerted by the
water molecule. It
depends on magnitude
of concentration
gradient.
 In cells, osmosis is
important to cell
survival. The water
molecules move quickly
through channels
formed by the integral
proteins.
 3 examples of osmosis with
respect to the solution.
1. Isotonic
2. Hypertonic
3. Hypotonic
ISOTONIC
Put a red blood cell (RBC) into a solution
which contains equal amounts of solute.
The water will flow from inside cell to
outside cell at equal rate and visa versa.
This happens because concentration is
equal on both sides. The state of
equilibrium of extracellular fluid is
ISOTONIC to intracellular fluid. (iso means
equal).
HYPERTONIC
Put a RBC into a solution
that contains a greater
concentration of solutes.
This means that there is
less water in the solution
then in the RBC, so water
will tend to flow out of the
cell. This causes the cell
to shrink. This is known
as crenation. The
extracellular fluid is
HYPERTONIC to the
intracellular fluid.
(hyper means above
normal).
 http://www.tvdsb.on.
ca/westmin/science/
sbi3a1/Cells/Osmosi
s.htm
HYPOTONIC
Put a RBC into a solution
that contains a lesser
concentration of solutes.
This means that there is
more water in the solution
then in the RBC, so water
will tend to move into the
cell. This causes the cell
to swell. This is known as
hypertrophy. The
Extracellular fluid is
HYPOTONIC to the
intracellular fluid. (hypo
means below normal)
 http://www.tvdsb.on.
ca/westmin/science/
sbi3a1/Cells/Osmosi
s.htm
III. Filtration
 Movement of molecules across a
selectively permeable membrane from a
region of high pressure to a region of
low pressure.
 Occurs in kidneys when waste product
urea is forced by pressure of blood to
cross membrane.
2. Active Transport
Needs energy from cell
(ATP)
Recall ATP  ADP +
PO4-2 + E
Active Transport
*Requires use of energy
(ATP)
*Transport of substances
against a concentration
gradient across a
selectively permeable
Membrane.
*Requires carrier proteins
for assistance.
*Needed to maintain
levels of ions inside cell
in spite of concentration
gradient.
*Also used for amino acids
to be carried into cell
where their numbers
are larger.
*CYTOSIS is the transport
of large volume of
materials and large
particles across the
membrane.
 There are 2 types:
endocytosis and
exocytosis.
1. Endocytosis
*Import material into the
cell
 A. Phagocytosis (fig. 310)
*Portion of membrane
forms pseudopod,
engulfs substance.
Substance is digested
by enzymes from
lysosome.
*Notable in WBC.
B. Pinocytosis “cell
drinking”
 *Bulk movement of
fluid into cell.
 *Only slight folding
of plasma.
 *Cells lining blood
vessels and
kidneys.
Endocytosis
2. Exocytosis
 Export material out of
cell.
 Releases either waste
products or molecules
manufactured in
cytoplasm.
 The membranes of the
organelles fuse with
plasma membrane and
release materials into
extra cellular
environment.
A. Excretion
*Removal of waste
materials
B. Secretion
*Releasing
molecules produced by
organelles into
Extracellular
environment. i.e.
Digestive enzymes,
mucous, hormones,
antibodies.
Exocytosis
Packets pp. 39-43
Quiz on pp.48-59 and all notes
from ch. 3
Followed by webquest on cell