Warm Up 12-02
Why do your cells need to transport
“stuff”? What would be some things they
would transport?
 Today:

Discuss diffusion and concentration gradients
 How osmosis functions

Warm UP 12-3
Explain how diffusion works, including the
concentrations needed for the substance
to move
 Today:

Begin egg lab
 Solutions (hypotonic, hypertonic, isotonic)

Homeostasis and Cell
Transport
Chapter 5

Diffusion –


the net movement of particles from an area
of higher concentration to an area of lower
concentration
Occurs because of the kinetic energy in
molecules (random movement)
DEMO

Diffusion in Water


EX: Food dye slowly diffuses b/c of the
movement of the water molecules and the
dye particles
Diffusion in air

EX: The odor molecules bounce against
each other and the gas molecules in the air
and slowly diffuse into the classroom.

Concentration Gradient –


difference in concentration of molecules
across a distance
Dynamic Equilibrium –
the condition in which there is continuous
movement but no overall change
 This means there no longer is a
concentration gradient

 there
equal
is no “high” and no “low” – everything is

Osmosis –
the diffusion of water molecules through a
selectively permeable membrane
 Diffusion of water goes from high
concentration to lower concentration


http://www.youtube.com/watch?v=sdiJtDRJQEc&feature=related
Draw
Which way will the water move?
Solution
Sucrose = 75%
Water = 25%
Cell
Sucrose = 25%
Water = 75%
Cell
Sucrose = 65%
Water = 35%
Solution
Sucrose = 35%
Water = 65%
Where will the water move?
What will happen?

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Reverse Osmosis
12-4
What is an hypotonic solution? What
happens to the movement of molecule in
an hypotonic solution?
 Then hand in your warm ups
 Today:

Continue with the Egg lab (get out your lab
sheet)
 Discuss turgor pressure, plasmolysis,
hypertonic solutions


Solution –


Homogeneous mixture (a uniform mixture) of two or
more substances
Example:


Solute:


Substance that is dissolved in another substance
Solvent:


Salt and Water
Thing that the solute is dissolved in
What is the most common solvent?

Water
Biology Warm Up 12-07
Describe why water leaves the cell in a
hypertonic solution.
 Today:

Continue with the lab
 Worksheet

Warm Up 12-08
Draw a graphic organizer for hypotonic,
hypertonic and isotonic solutions. Tell me
which way the water moves for each and
what happens to the cell
 Today:

We will finish our egg lab today
 Take notes on turgor pressure and
plasmolysis

Bio Warm Up 12-10


1.
2.
3.
Get out a clean piece of paper you can turn
in
Questions:
What is osmosis?
What is a hypertonic solution? What
happens to the cell in this type of solution?
What is a hypotonic solution? What
happens to the cell in this type of solution?

Isotonic Solution –


a solution in which the concentration of
solutes outside the cell (ex: salts) is the
same as the concentration of solutes
inside the cell
Would osmosis occur in this situation?

No, because there is no concentration
gradient (no net movement)

Hypotonic Solution –
solution in which the concentration of solutes (ex salts) is LOWER than the solute concentration inside
the cell
Which way will the water move?
 into the cell  cell will swell / burst



If we put Elodea leaves in a hypotonic solution,
what happens?

Water will move into the cell to dilute the salts – this
causes the cell to swell
 Turgor
Pressure –
 the
pressure that exists inside a cell
caused by water
 High turgor pressure can cause animal cells
to burst. Why?


They do not have a cell wall.
What would happen if there is low turgor
pressure in plants?
Causes them to wilt
 Then you water the plant and it will regain the
pressure and stand up straight


Hypertonic Solution –

solution in which the concentration of solute (ex salt)
is higher outside than the concentration inside the cell
Which
direction will the water move?
 Out

of the cell
What will happen to an Elodea Leaf in a
hypertonic solution?


Water will leave the cell
Plasmolysis –

Water will leaves the cell, and result in shriveling of the cell
Warm Up 12-11
What is plasmolysis? What would happen
to the plant cell? What is turgor pressure?
What happens to the plant if there is low
turgor pressure? High turgor pressure?
 Today:

Discuss plasmolysis and turgor pressure
 View the effects of a hypo / hypertonic
solution on Elodea leaves

Summary of Hypo/Hypertonic solution
changes on a RBC.
Biology Warm ATB 12-14


What is the function of the contractile vacuole?
Why do some cells need them?
Today:

Turn in egg lab!





1st page - Rubric
2nd page – lab write up
3rd page – graph
4th page – lab direction sheet
Assignment – read pages 97-102


Do Questions #1-8
Turn in when done
ATB 12-15
What would happen to a grape placed in
highly concentrated sugar water? Why
would this happen?
 This Week:



Test Friday!
Today:
Selective permeability
 Active transport

Review
If the cell shrinks, it is in what type of solution?
 If the cell is at equilibrium with it’s
environment, its in what type of solution?
 If the cell swells, it’s in what type of solution?

Water –90%
Water 95%
Salt – 10%
Salt 5%
Water 50%
Water 50%
Salt 50%
Salt 50%
Water 64%
Water 44%
Salt 36%
Salt 56%
 Contractile
 Organelle
Vacuoles –
that excretes excess water
from cells
Uses energy
 Usually found in unicellular freshwater
organisms.
 This prevents them from bursting in a
hypotonic solution.


Contractile vacuole
 Plasmolysis
–
 loss
of turgor pressure in plant cell
due to loss of water
 What happens to a plant during
plasmolysis?
The plant wilts
 The plants plasma membrane and cytoplasm
will shrink away from the cell wall

Starting
Mass
(grams)
Egg Lab Report

Graph



Must be colored
Graph your starting
mass and then use
your final mass data
which is in blue
Egg in
shell
Vinegar
Corn
Syrup
Distilled
“Percent Change in Mass”


Change
in mass
(g)
% Change in Mass
((Initial Mass – Final
Mass) / Initial Mass) x
100
Add a column to you data table:

Final
Mass
(g)
((Initial Mass – Final Mass) / Initial
Mass) x 100
Calculate all the changes in mass for
your egg
=====
====
===
Egg Lab Report

Analysis of your Data:



Be sure you are using the terms we’ve discussed in
class in your explanation of your results.
Example
What you should turn in:




Page 1 – Directions
Page 2 – Written lab report
Page 3 – Graph
Page 4 – Your actual lab procedure

Selective Permeability –


plasma membrane to allows some
materials to pass while keeping others out
Why is selective permeability important?

So the cell can allow important substance
in (water, oxygen, glucose) and keep
harmful substances out (bacteria).
Passive Transport

Passive Transport –

movement of particles across membranes by
diffusion
 This
process uses no energy
 Molecules
low conc
moving from hi conc 
 Facilitated
 name
Diffusion –
for passive transport using
transport proteins
 Does not use energy!!!
 Example:
– going from high conc.
Outside cell low inside the cell
 Glucose
Transport through the cell membrane:
 Transport proteins –


proteins that assist facilitated diffusion
Warm Up 12-16
What is the function of transport proteins?
What is the function of the ion channels?
 TEST FRIDAY! RS due Friday!
 Today:


Finish notes – Na + / K + pump, endocytosis,
exocytosis

Ion channels –




proteins – transport ions from high concentration to
lower concentration
Ions (like Na+, Ca+, etc) are not soluble in lipids, so
they must travel through proteins channels
Ion channels are ion specific
Some channels are always open, some have
gate

Gates open from stimuli: stretching of cell membrab.,
electrical or chemical signals
Active Transport

Active Transport –


transport of materials against a concentration
gradient – requires energy
ATP (adenosine tri-phosphate) –



the ENERGY molecule for the cell
Breaks down from
ATP  ADP (Adenosine
di-phosphate)
Hydrolysis of the
phosphate releases
energy
Active Transport Example
http://www.youtube.com/watch?v=STzOiRqzzL4&feature=related

Sodium-potassium Pump –
transfer protein example
 Transfers Na+ out and K+ in

Creates electrical gradient
 Important for nerve impulses


http://www.youtube.com/watch?v=bGJIvEb6x6w&NR=1
Na+ / K+ Pump

Endocytosis –


when a cell surrounds and takes in
material from the environment
Uses ____Energy___
Warm Up 12-17
Draw a picture illustrating endocytosis
 Test / RS tomorrow!
 Today:

Review for test
 Work on review sheet

Endocytosis

Pinocytosis –

Transport of fluids into the cell

Phagocytosis –


Transfer of large particles / cells into the cell
Phagocytes –


Cells that ingest bacteria / viruses –
lysosomes fuse w/ vesicle to destroy them
before harm done
http://www.youtube.com/watch?v=1w10R9lv7eQ

Exocytosis –
when a cell expels materials to the
extracellular environment
 Cell exports proteins, hormones and wastes
this way
 This process uses ___Energy___

Endo / Exocytosis
Exocytosis and endocytosis
 http://www.youtube.com/watch?v=K7yku3
sa4Y8


The End
Hypo / Hypertonic Solutions