Download Transport Notes

Transport
• In order to live, all cells must take in
nutrients and eliminate wastes
• Nutrients and waste materials must cross
the cell membrane between the solution
outside the cell and the solution inside the
cell.
Concentration
• Amount of substance within a solution.
• Concentration gradient: The difference in
concentration of a substance from one
location to another. Movement along the
gradient occurs from high to low.
•Several processes are involved
in moving materials across the
cell membrane and can be
classified as either passive or
active transport
• Passive transport: the
movement of a
substance across a cell
membrane without the
input of the cell’s
energy – with the
concentration gradient
(high to low).
Examples include
diffusion, facilitated
diffusion and osmosis.
• Active transport: uses
cellular energy to
move substances
across a cell
membrane –
opposite of
concentration
gradient (low to
high)
Solutions
Solution: mixture of substances that is the same
throughout—it is homogenous. Example: Koolaid
Solvent: Water. (liquid substance that dissolves another
substance-water is the solvent for many solutions).
Solute: Often Solid particles that have a charge are
dissolved by water or other solvent liquid. Example:
sugar is a charged solid before mixing with water
Passive Transport: Diffusion
Cell Homeostasis
• Passive transport: Diffusion: the
random movement of solute or gas
from an area of higher concentration
(more molecules) to an area of low
concentration (fewer molecules)
Cell Homeostasis
• Simple diffusion enables oxygen and
carbon dioxide to cross the cell membrane
• Diffusion occurs down a concentration
gradient and does not require energy
from cell!
Think – Pair - Share
• What is going to make this
process happen faster?
• The rate of diffusion depends
on:
– Temperature
– Size of the molecule
Homeostasis: Passive Transport
•When the molecules are
evenly dispersed on both sides
of membrane. The net
movement is equal.
• This is called
equilibrium
Word play
•How are you going to
remember what equilibrium
means?
•Some molecules diffuse
across the cell membrane
with the help of carrier
proteins in the membrane
Nothing to write
• Facilitated diffusion: the
passive process of transporting
molecules by carrier proteins
during diffusion; requires NO
energy output-passive
transport.
• Always moves down a
concentration gradient from
an area of high concentration
to an area of low
concentration.
• ex: the movement of glucose from the blood
into body cells
Why?
Why do we need to get glucose
into our cells?
http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter2/animation__h
ow_facilitated_diffusion_works.html
Homeostasis
Facilitated diffusion Review:
1.Facilitated diffusion requires
A) enzymes. B) carrier transport proteins. C) lipid carriers. D) carbohydrate
carriers. E) lipid or carbohydrate carriers.
2. Facilitated diffusion occurs
A) into the cell only. B) out of the cell only. C) in either direction depending
on the temperature. D) in either direction depending on the
concentration gradient of the molecules. E) in either direction depending
on the size of the molecule.
3. Facilitated diffusion is used to transport
A) sugars and amino acids. B) H2O and O2. C) CO2 and O2. D) CO2 and
H2O. E) sugars and H2O.
4. Unlike simple diffusion, facilitated diffusion requires energy expenditure by
the cell. A) True B) False
5. Facilitated diffusion requires a specific transporter for a specific molecule. A)
True B) False
Passive Transport:
Osmosis:
the
diffusion
of water
across a
semipermeable
membrane
Osmosis
• Form of passive transport
• Occurs when the concentrations of
solutes in the membrane are
different
• Water moves from solutions with
high water concentration to
solutions with low water
concentration—water moves toward
solute/solid
Solutions
• Hypotonic: A solution that has a lower concentration
of solutes.
• Isotonic: Equal concentration of solutes on each side.
• Hypertonic: A solution that has a higher concentration
of solutes.
** These are comparison terms**
Cell contents
are equal
Cell Expands
Cell shrinks
Cell Homeostasis
Watch this: Osmosis/diffusion of substances through membrane (don’t
forget the QUIZ after!)
And
http://www.phschool.com/science/biology_place/labbench/lab1/ex1.h
tml
Osmosis and Turgor pressure
• Osmosis causes water from the environment to
move into the vacuole and pushes the
cytoplasm and cell membrane against the plant
cell wall. If the plant has enough water
available, the plant cells will stay rigid. If the
plant is lacking water, or the surrounding water
is hypertonic, water will leave the plant and it
will wilt.
Cell shrinks
equal
Cell Expands
Turgor pressure in a plant cell is analogous to
air pressure in a car tire;
Cell Homeostasis
Cells in hypotonic, isotonic, and hypertonic
solutions:
http://www.youtube.com/watch?v=IRQLRO3
dIp8
Cell Homeostasis
Example: Saltwater or
corn syrup
Example: Distilled
water
Cell has more
solute than
solution
Gummy Bear Osmosis % change
• Step 1: Calculate Change (subtract original value from
the new value) (EXAMPLE: You had 5, but now you
have 7=2)
• Step 2: Divide that change by the original value (you
will get a decimal number) (EXAMPLE: 2/5= 0.4)
• Step 3: Convert to a percentage (by multiplying by 100
and adding a "%" sign) (EXAMPLE: 0.4 x100=40%)
• Note: if the new value is greater then the old value, it
is a percentage increase, otherwise it is a decrease.
Solutions
• For each of the following determine the solute and
solvent percentages for the solution outside the cell
(environment) and for the inside of the cell. Then...
• A) Tell whether the solution outside the cell is
hypotonic, hypertonic or isotonic.
• B) Give the direction of the net movement of water (
into the cell, out of the cell, or into & out of the cell at
equal rates)
• C) Tell what will happen to the cell (shrink, swell or
stay the same)
Scenario-You stay in the pool or Lake
Unpleasant too long:
A. Hypotonic (80% water solvent)
B. Water will move inside the cell toward
solute
C. Cell will swell
Scenario-You are stranded in ocean and
drink too much seawater
A. Hypertonic (90% solute-”salt” in this
instance)
B. Water will move outside the cell toward
solute
C. Cell will shrink
Solutions
• What type of solution would have a 50%
each of solute (iodine) and solvent
(water)?
• What is the net movement of water in this
type of solution?
• What will happen to the cell?
If passive transport is going down a
slide, then what is active transport?
ACTIVE TRANSPORT: Movement of a substance
against a concentration gradient from areas of lower
concentration to areas of higher concentration
http://www.dnatube.com/video/1589/Cellulartransprot-of-sodium-and-potassium-active-transport
Active Transport
• Always requires energy
• Often involves carrier proteins
• The energy source for active transport is
ATP
• Active transport is important in
maintaining proper ion concentrations
inside the cell
• Helps with muscle contractions and
transmission of nerve impulses
• In plants, it enables roots to absorb
nutrients from the soil.
Active Transport examples:
• Endocytosis: Large molecules moved
into the cell via vesicle. There are two
types:
• http://www.susanahalpine.com/anim/
Life/endo.htm
1. Phagocytosis: The process by which
solid material is engulfed by a cell. – this
is how our white blood cells get rid of
foreign bodies in our blood.
http://www.cellsalive.com/mac.htm
Active Transport
2. Pinocytosis: Movement by vesicle in which
liquids are brought in or moved out of the cell.
This is used because they are unable to move
through the lipid bilayer.
Active Transport
• Exocytosis: Large particles moved out of
the cell via vesicle (the last stage of
endocytosis).
Cell Homeostasis
Summary of the passive and active methods of cell molecule transport:
• http://www.pbslearningmedia.org/resource/tdc02.sci.life.cell.membraneweb/c
ell-membrane-just-passing-through/
The proton pump is an indirect active transport used
by mitochondria and chloroplasts that gets its energy from
the potential energy of the concentration gradient of H+
protons.