Some things to consider before we start
Molecules in solids, liquids, and gases
are always moving.
In which state of matter are molecules
moving the fastest?
• Gas
Slowest?
• Solid
• http://www.harcourtschool.com/activity/states_of_matter/
Some things to consider before we start
Substances must go through the cell
membrane in order to get in or out of
a cell.
Some things to consider before we start
• What substances need to go IN to a cell?
– Water, food/glucose/, oxygen
• What substances need to go OUT of a
cell?
– Wastes, carbon dioxide
• Cell Membrane Movie
CELL MEMBRANES
• … are selectively permeable, which means
that they allow some substances to pass
through but not others.
• Selective means “choosy” and
• Permeable means “to go through”
Cell Transport Video
https://app.discoveryeducation.com/search?Ntt=cell+transport
AIM : Cell Transport – Passive
Transport
Do Now:
What would happen if cell membrane
was fully permeable to all substances in
the cell’s environment?
Diffusion
• Molecules will always move from an
area where they are more
CONCENTRATED to an area where
they are less CONCENTRATED. This
is called diffusion.
What does concentrated mean?
• How many particles are packed in
an area
Diffusion continues until the
molecules of a substance are evenly
distributed in an area.
• This state of “evenly spread” is called
equilibrium.
• Do molecules stop moving once
equilibrium is reached?
• NO
http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_diffusion_works.html
http://www.wisc-online.com/objects/index_tj.asp?objid=AP1903
Diffusion by Brainpop
… is a special kind of diffusion that is
very important to living things.
Osmosis is the diffusion of water
through a selectively permeable
membrane.
This is the manner in which water
gets into and out of cells.
Animation: How Osmosis Works
http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_osmosis_works.html
• Water molecules will naturally flow
from an area in which the water
molecules are in greater numbers to
an area where they are in fewer
numbers.
http://www.biologycorner.com/bio1/diffusion.html
• Which way are water molecules
moving when a plant begins to wilt?
• Out of the cells
Passive transport
requires no ENERGY from the cell.
Diffusion and osmosis are examples of
passive transport.
Molecules in the cell membrane called
transport proteins help to move LARGER
molecules into or out of the cell. This still
does not require energy. Think of this as
being like taking a ferry ride without
having to pay. This is called Facilitated
transport
facilitated transport
http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter2/ani
mation__how_facilitated_diffusion_works.html
AIM : What is Active Transport ?
Do Now
Predict Outcome – What would happen
if the cell was exposed to a drug that
disabled the transport proteins in the
cell membrane?
Active transport
requires ENERGY and uses transport
proteins in the cell membrane.
Used when cells need to move substances
from areas of lower concentration to an area
of higher concentration. This is the opposite
of DIFFUSION and requires energy.
Other types of active transport
endocytosis
o Endocytosis occurs when VERY LARGE
THINGS need to move INTO a cell.
o A vesicle fuses to the cell membrane and
then releases an object into the cell.
o A white blood cell “eating” a BACTERIA
would be an example of endocytosis.
o What does “endo” mean? “IN”
Exocytosis
o Occurs when VERY LARGE molecules need
to move OUT of a cell.
o A vesicle fuses to the cell membrane and
then releases an object out of the cell.
o An example of exocytosis is when proteins
packaged by the GOLGI BODIES need to
move out of the cell, to get to another cell.
o What does “exo” mean? OUT OF
Let’s get some practice:
Tell if each of the following as diffusion, osmosis, facilitated
transport, active transport, endocytosis, or exocytosis.
• Large waste molecules stored in
vacuoles need to be moved out of a
cell:
• exocytosis
Water concentration outside a cell is
85%. Water concentration inside the
cell is 70%. Water flows into the cell:
• Osmosis
85%
70%
• You can smell the cookies baking in
the oven even before you enter the
kitchen:
• Diffusion
The concentration of Na ions outside
the cell is 10%. The concentration of
Na ions inside the cell is 25%. Na ions
move into the cell.
• Active Transport
25%
10%
A one-celled organism “eats” another
one-celled organism:
• Endocytosis
• Glucose molecules are helped to move
into the cell by transport proteins in
the cell membrane, but no energy is
used to do this:
• Facilitated transport
Great Animation
http://www.northland.cc.mn.us/biology/Biology1111/animation
s/transport1.html
Some additional facts about cell
transport:
Simple Diffusion – only small, nonpolar
molecules e.g. Oxygen, Carbon Dioxide,
Steroid Hormones.
Facilitated diffusion – Ions and polar
molecules e.g. sugars, amino acids, water.
Uses two types of transport proteins –
Channel proteins and carrier proteins.
AIM : What are solutions ?
Do Now :
Predict what would happen to the
concentration of the solution if we will
add more of a substance dissolved in it
?
Solution
• a mixture of two or more substances that is
identical throughout
Salt water is
considered a
• can be physically separated
solution. How
• composed of solutes and solvents
can it be
physically
separated?
the substance in the
smallest
amount and the one that
dissolves in the solvent
Iced Tea Mix
(solute)
the substance in the
larger
amount that dissolves
the solute
Iced Tea
(solution)
Water
(solvent)
milk, fog, jello are considered solutions
Solutes Change Solvents
• The amount of solute in a solution determines
how much the physical properties of the
solvent are changed
• Examples:
Lowering the Freezing
Point
The freezing point of a liquid solvent
decreases when a solute is dissolved in it.
Ex. Pure water freezes at 320F (00C), but when salt is
dissolved in it, the freezing point is lowered.
This is why people use salt to melt ice.
Raising the Boiling
Point
The boiling point of a solution is higher
than the boiling point of the solvent.
Therefore, a solution can remain a liquid at
a higher temperature than its pure solvent.
Ex. The boiling point of pure water is 2120F (1000C),
but when salt is dissolved in it, the boiling
point is higher. This is why it takes salt water
longer to boil than fresh water.
Concentration
• the amount of solute dissolved in a
solvent at a given temperature
•described as dilute or
unsaturated if it has
a low concentration of
solute
•described as saturated if it
has a high concentration of
solute
•described as supersaturated if
contains more dissolved solute
than normally possible
Solubility
• the amount of solute that dissolves in a
certain amount of a solvent at a given
temperature and pressure to produce a
saturated solution
• influenced by:
Temperature
Pressure
Solids increased temperature causes
them to be more soluble and vice versa
Solids increased pressure has no
effect on solubility
Gases increased temperature causes
them to be less soluble and vice versa
Gases increased pressure causes them
to be more soluble and vice versa
Ex. Iced Coffee
Ex. Soda,
AIM : How can we use solubility
curves?
DO NOW :
Explain why it would be possible to
dissolve much more NaCl in hot
water than in cold water?
Because an increase in temperture
will increase the solubility of the
substance.
Solubility curve
Saturated
Supersaturated
Unsaturated
Solubility curve
• Any point on a line
represents a saturated
solution.
• In a saturated solution,
the solvent contains the
maximum amount of
solute.
• Example
• At 90oC, 40 g of NaCl(s) in
100g H2O(l) represent a
saturated solution.
Solubility curve
• Any point below a line
represents an
unsaturated solution.
• In an unsaturated solution,
the solvent contains less
than the maximum amount
of solute.
• Example
• At 90oC, 30 g of NaCl(s) in
100g H2O(l) represent an
unsaturated solution. 10 g
of NaCl(s) have to be
added to make the solution
saturated.
Summary :
1. Name a solute and a solvent in following
solutions :
Sugar Water , Club Soda, Sea Water.
2. A solution that contains less solute than it
can hold at a given temperature is said to be
________________
3. Name two factors that affect solubility.