The document discusses cellular transport and the plasma membrane. It describes the key functions of the plasma membrane including absorption and circulation of materials through the organism. The plasma membrane is selectively permeable and uses both passive and active transport mechanisms. Passive transport includes diffusion, facilitated diffusion, and osmosis which move molecules down concentration gradients without energy. Active transport uses ATP and transport proteins to move molecules against concentration gradients. Endocytosis and exocytosis are described as mechanisms to transport larger particles and molecules into and out of cells.

2.  the life function that involves
the absorption (taking in)
and circulation (moving around) of materials
throughout an organism.

3. • the process where digested (broken down)
nutrients as well as other dissolved
materials enter the cells of an organism
• the key organelle that is involved with this life
function is the PLASMA (CELL) MEMBRANE

4. Polar heads Fluid Mosaic
love water Model of the
& dissolve. cell membrane
Non-polar
Membrane move
tails hide
from water.
Carbohydrate cell
markers
Proteins

5.  Cell membranes have pores (holes) in it
a.Selectively permeable: Allows some
molecules in and keeps other molecules
out
b. The structure helps it be selective!
 Size (macro or micro), charge (+ or -) and solubility (lipid-
soluble or not) affect a molecule’s ability to cross the cell
membrane.
 In general, small noncharged, lipid-soluble molecules
easily cross the cell membranes

6. Remember. it is a
double lipid layer with
floating proteins...
We also can call the plasma
membrane the fluid mosaic model.
Fluid because the double layer
moves around, it never is motionless.
A mosaic because that is how it
appears--a mosaic is a piece of art
that is made up of lots of little pieces
put together.

7. a. Phosphate head is polar
(hydrophilic or water loving)
b. Fatty acid tails non-polar
(hydrophobic or water
fearing)
c. Proteins embedded in
membrane

8. • the transport of materials within one cell and/or the
transport of materials throughout a multicellular
organism
• for unicellular organisms, intracellular (inside the
cell) circulation is accomplished by
the endoplasmic reticulum, Golgi complex,
and CYCLOSIS (cytoplasmic streaming).
• for multicellular organisms, intercellular (between
cells) circulation is accomplished by the diffusion or
transport through vascular tissues (like xylem,

11. (HighLow)
 * it is called passive transport because NO
ENERGY or ATP IS REQUIRED!!! Weeee!!!
1. Diffusion
2. Facilitated
Diffusion high
3. Osmosis
Tonicity
low
Water Potential

12. 1. Diffusion
2. Facilitated Diffusion – diffusion with the
help of transport proteins
3. Osmosis – diffusion of water

13. • *diffusion is where very small
particles move from a region of high concentration (a large
amount) to a region of lower concentration (a smaller
amount).
• * molecules move in straight lines in a random direction
• * diffusion usually happens until the concentration is the
same throughout; this is called EQUILIBRIUM (a balanced
state-- HOMEOSTASIS!)
• Note: molecules will still move around but stay spread out.

14.  Occurs in liquid or gas medium
Diffusion of a solute within a solvent is affected
by several factors:
 Temperature
 Pressure
 Density of the solvent
 Concentration Gradient
 Solubility of the solute
http://bio.winona.edu/berg/Free.htm

17. * larger molecules such
as polysaccharides,
proteins, and lipids
cannot fit, because they
are too big

18. Passive Transport:
2. Facilitated Diffusion
2. Facilitated diffusion: diffusion of specific particles through
membrane transport proteins to help them move through the
cell membrane
a. Transport Proteins are specific – they “select” only certain
molecules to cross the membrane
b. Transports larger or charged molecules
c. Concentration gradient required – can’t transport from low to
high concentration
d. Energy not needed
e. Rate of transport reaches a maximum when all membrane
transport proteins are used up (saturated)
f. Membrane transport proteins are sensitive to inhibitors that
can cause them not to function

19. Passive Transport:
2. Facilitated Diffusion A B
There are 2 types of membrane
transport proteins involved:
 Channel proteins – contain
tunnels/openings that serve as Facilitated
passageways of molecules Diffusion
diffusion (Lipid Bilayer)
(Channel
 Carrier proteins – undergo
Protein)
temporary binding to the
molecule it carries resulting in
conformational change that
moves the molecule through
the membrane Carrier Protein

20.  the diffusion of water through a semi-permeable
membrane

21. •Water moves freely
through pores.
•Solute (green) to large
to move across.

22. Water Potential – term for movement of water
molecules as it undergoes osmosis
- The measure of the difference between the “force”
that pushes water molecules and the “force” exerted
by the membrane
Water solution with less solute (more diluted solution because of more water) =
higher water potential
Water solution with more solute (more concentrated solution) = lower water
potential
Water Potential Gradient - when 2 solutions of different water potentials are
separated by a semipermeable membrane, thus allowing osmosis to occur
Osmotic Pressure – “force” that moves water molecules through a semi-
permeable membrane

24. If the concentration of solute (salt) is equal on both sides, the water will
move back in forth but it won't have any result on the overall amount of
water on either side.
"ISO" means the same

26. "HYPO" means less
In this case there are less solute
(salt) molecules outside the cell,
since salt sucks, water will move
into the cell, causing it to swell.
The cell will gain water and grow
larger. As osmosis continues,
osmotic pressure builds up inside
the cell causing cell lysis.
In plant cells, the vacuoles will fill and the plant becomes stiff and rigid.
The pressure exerted by the water molecule is called TURGOR
PRESSURE, and the phenomenon TURGIDITY. The turgor pressure in
plants will not result in cell lysis as the cell wall keeps the plant from
bursting.
TURGIDITY is important in maintaining the firm and erect position of a
plant.

27. • Osmosis
Animations for
isotonic, hypertonic,
and hypotonic
solutions
Hypotonic: The solution has a lower concentration of
solutes and a higher concentration of water than
inside the cell. (Low solute; High water)
Result: Water moves from the solution to inside the
cell): Cell Swells and bursts open (cytolysis)!

29. "HYPER" means more
In this case there are more solute (salt) molecules outside the cell, which
causes the water to be sucked in that direction.
Causes cells to shrink and lose shape because of water loss.
In plant cells, the central vacuole loses water and the cells shrink, causing
wilting (plasmolysis). In animal cells, the cells also shrink.
In both cases, the cell may die.

30. • Osmosis
Animations for
isotonic, hypertonic,
and hypotonic
solutions
Hypertonic: The solution has a higher concentration
of solutes and a lower concentration of water than
inside the cell. (High solute; Low water)
shrinks
Result: Water moves from inside the cell into the
solution: Cell shrinks (Plasmolysis)!

32. Passive Transport:
3. Osmosis
Tonicity – strength
of a solution in
relation to osmosis
3 Types:
Isotonic
Hypotonic
Hypertonic
Remember: Salt is a solute, when it is concentrated inside or outside
the cell, it will draw the water in its direction. This is also why you
get thirsty after eating something salty.

34. What type of solution are these cells in ?
A B C
Hypertonic Isotonic Hypotonic

35. •Bacteria and plants have cell walls that prevent them
from over-expanding. In plants the pressure exerted on
the cell wall is called tugor pressure.
•A protist like paramecium has contractile vacuoles that
collect water flowing in and pump it out to prevent them
from over-expanding.
•Salt water fish pump salt out of their specialized gills so
they do not dehydrate.
•Animal cells are bathed in blood. Kidneys keep the
blood isotonic by remove excess salt and water.

36.  * a process where a cell USES ENERGY or
ATP to move molecules from a region of
low concentration to a region of high
concentration
 * special proteins called carrier proteins
This is
often called pumps are used to move gonna
be hard
molecules from one side of the membrane work!!
high
to the other
low

37. Example: Sodium
-Potassium Pumps
are important in nerve
responses. They
transfer Na and K
ions in and out of the
nerve and muscle
cells.
Protein changes shape to move molecules:
this requires energy!

41. 1. Endocytosis
Phagocystosis
Pinocytosis
Receptor-mediated
2. Exocytosis

43.  EXOCYTOSIS – going out of the cell
 ENDOCYTOSIS - going inside the cell
Pinocytosis:
* a process where very large (too big to go
through the plasma membrane) particles are
"sucked in" to a cell, forming a vacuole.
* "cell drinking"--uses energy (active transport)

44. 1. Endocytosis: taking bulky material
that can’t use transport proteins
(like macromolecules) into a cell
• Uses energy
• Cell membrane in-folds around
the macromolecule to be
transported
• 3 Types:
 Phagocytosis
 Pinocytosis
 Receptor-mediated Endocytosis

46.  ENDOCYTOSIS - going inside the cell
Phagocytosis:
* a process where a cell engulfs large
undissolved particles, forming a vacuole
* "cell eating"--uses energy (active transport)

48. Receptor-mediated Endocytosis – “cell drinking”
- Compared to pinocytosis, is very specific. The plasma membrane
becomes indented and forms a pit. The pit lined with receptor
proteins picks specific molecules from its surroundings. The pit will
close and pinch off to form a vesicle which will carry the molecules
inside the cytoplasm.

49. 2. Exocytosis: Forces material
out of cell in bulk
• membrane surrounding the
material fuses with cell
membrane
• Cell changes shape –
requires energy
• EX: Hormones or wastes
released from cell