Transcript Cellular Transport Notes

Cellular Transport
Notes
Ch. 7.2 Plasma Membrane (p.175-178)
Ch. 8.1 Cellular Transport (p.195-200)
Cell Membranes
ALL cells have a Cell
Membrane
2. Functions:
a. Controls what enters
and exits the cell to
maintain an internal
balance called
homeostasis
b. Provides protection and
support for the cell
1.
TEM picture of a
real cell membrane.
Cell Membranes (continued)
3.
Structure of cell membrane
Lipid Bilayer -2 layers of
phospholipids
Phosphate head is polar
(water loving)
b. Fatty acid tails non-polar
(water fearing)
c. Proteins embedded in
membrane
a.
Phospholipid
Lipid Bilayer
Polar heads Fluid Mosaic
love water
Model of the
& dissolve. cell membrane
Non-polar
tails hide
from water.
Carbohydrate cell
markers
Proteins
Membrane
movement
animation
Cell Membranes (continued)

4. Cell membranes have pores (holes) in it
which makes it Selectively Permeable:
Allows some molecules in and keeps other
molecules out (the structure helps it be
selective!!)
Pores
Structure of the Cell Membrane
Outside of cell
Proteins
Lipid
Bilayer
Transport
Protein
Animations
of membrane
Go to structure
Section:
Carbohydrate
chains
Phospholipids
Inside of cell
(cytoplasm)
Cell Membrane
“Use Textbook”
ANSWER THE FOLLOWING:
1. What is the function of the cell membrane? (p. 175)
2. Describe the structure of the cell membrane? (p. 176)
3. How many layers of lipids are there in the plasma membrane? (p. 177)
4. What are the proteins called that are found within the plasma membrane? (p.177)
5.Why is the structure of the cell membrane referred to as a “mosaic?”? (p.178)
Cell Concentrations

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Cells are surrounded
and filled with a liquid
environment
The cytoplasm
contains a solution of
different substances.
Cell Concentrations

A solution is a
mixture of two or
more substances.
 Solute –
dissolved
substance
(salt/sugar)
 Solvent –
dissolves solute
(water)
Cell Concentrations

Substances will move
across the cell
membrane if their
concentrations are
unequal.

Isotonic Solution
Osmosis Animations
for isotonic,
hypertonic, and
hypotonic solutions
Isotonic: The concentration of solutes in the solution
is equal to the concentration of solutes inside the cell.
Result: Water moves equally in both directions and
the cell remains same size! (Dynamic Equilibrium)
A cell in an isotonic solution
Water
moves in
and out
at the
same rate
10%
Solute
How much solvent
inside?
90%
solvent
Cell remains the same!
10%
Solute
How much solvent
outside?
90%
solvent
Hypotonic Solution

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)!
A cell in a hypotonic solution
Water
moves in
20%
Solute
How much solvent
inside?
80%
solvent
Cell swells!
10%
Solute
How much solvent
outside?
90%
solvent
Hypertonic Solution

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)!
A cell in an hypertonic solution
Water
moves
out
10%
Solute
How much solvent
inside?
90%
solvent
Cell shrinks!
20%
Solute
How much solvent
outside?
80%
solvent
What type of solution are these cells in?
A
B
C
Hypertonic
Isotonic
Hypotonic
Types of Cellular Transport
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2.
3.

Weeee!!
!
Passive Transport
cell doesn’t use energy
1.
Diffusion
Facilitated Diffusion
Osmosis
•Animations of Active
Transport & Passive
Transport
high
low
Active Transport
cell does use energy
1.
2.
3.
Protein Pumps
Endocytosis
Exocytosis
This is
gonna
be hard
work!!
high
low
Passive Transport
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
cell uses no energy
molecules move randomly
Molecules spread out from an area of
high concentration to an area of low
concentration.
(HighLow)
3 Types of Passive Transport
1.
2.
3.
Diffusion- diffusion of particles
Facilitative Diffusion – diffusion with
the help of transport proteins
Osmosis – diffusion of water
Passive Transport:
1. Diffusion
1.
Diffusion: random
movement of particles from
an area of high
concentration to an area
of low concentration.
(High to Low)
•
Diffusion continues until all
molecules are evenly spaced
(equilibrium is reached)-Note:
molecules will still move around
but stay spread out.
Simple Diffusion
Animation
Passive Transport:
2. Facilitated Diffusion A
2. Facilitated diffusion:
diffusion of specific particles
with HELP from a
transport proteins
a. Transport Proteins are
specific – they “select”
only certain molecules
to cross the membrane
b. Transports larger or
charged molecules
(sugar)
Facilitated
diffusion
(Channel
Protein)
Carrier Protein
B
Diffusion
(Lipid
Bilayer)
Passive Transport: 2. Facilitated Diffusion
Glucose
molecules
Cellular Transport From aHigh Concentration
High

Cell Membrane
Low Concentration
Through a 
Go to
Section:
Transport
Protein
Protein
channel
Low
Channel Proteins
animations
Passive Transport:
3. Osmosis
Osmosis
animation
3.Osmosis: diffusion
of water through a
selectively permeable
membrane
 Water moves from high
to low concentrations

•Water moves freely
through pores.
•Solute (green) to large
to move across.
How Organisms Deal
with Osmotic Pressure

Paramecium
(protist) removing
excess water
video
•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.
Active Transport
•cell uses energy (ATP)
•actively moves molecules to where they are
needed
•Movement from an area of low concentration
to an area of high concentration
(Low  High)
3 Types of Active Transport
1.
2.
3.
Protein Pumps- transport
macromolecules across the cell
membrane
Endocytosis- material ENTERING
the cell
Exocytosis- material EXITING
the cell
Types of Active Transport
1. Protein Pumps transport proteins that
require energy to do
work
•Example: Sodium /
Potassium Pumps are
important in nerve
responses.
Sodium
Potassium Pumps
(Active Transport
using proteins)
Protein changes
shape to move
molecules: this
requires energy!
Types of Active Transport

2. Endocytosis: taking
bulky material into a cell
•
Uses energy
•
Cell membrane in-folds
around food particle
Aka: “cell eating”
•
forms food vacuole &
digests food
(This is how white blood
cells eat bacteria!)
2 Types of Endocytosis…
1) Phagocytosis:
large
PARTICLES are
engulfed
2) Pinocytosis:
WATER drops
are engulfed
Types of Active Transport
3. 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
•
Endocytosis &
Exocytosis
animations
Compare:
Passive to Active Transport
Passive Transport
-Moves from HIGH to LOW
3 Types:
1) Diffusion- particles move
fm H to L
2) Osmosis- water moves fm
H to L
3) Facilitated Diffusionparticles move fm H to L with
the HELP of transport protein
REQUIRES NO ENERGY
(ATP)

Active Transport
Moves from LOW to HIGH
3 Types:
1) Endocytosis- particles into
the cell
2) Exocytosis- particles exists
the cell
3) Protein Pump- particles
moves with HELP of a
transport protein with ATP
REQUIRES ENERGY (ATP)
