Bio H – The Cell
Cell Transport: moving things in and out of the cell
To understand cell transport, you need to understand the structure of the cell membrane, and the components of the
cell membrane. Go to Chapter 4. Read pp 77-78. Draw the cell membrane, and identify the following structures (ie.
Don’t just copy the picture, think about what type of protein receptor and transport proteins are, as compared to the
enzyme show in the picture. Use information from pages 78-79 and the following website:
http://www.susanahalpine.com/anim/Life/memb.htm (no audio)
https://www.youtube.com/watch?v=svAAiKsJa-Y (audio) – watch the whole thing, but we will work on
understanding.
Label the following on a HAND DRAWN diagram. You will need to use both the book and the website. Fluid mosaic
model, plasma membrane (cell membrane) Phospholipid bilayer (hydrophilic head and hydrophobic tail); integral
protein, peripheral protein, transport protein, receptor protein, glycoprotein, cholesterol
DIAGRAM:
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Bio H – The Cell
Plasma membrane:
_____________________________________that surrounds all cells and certain organelles within the cell. Contains
proteins, cholesterol and carbohydrates as well.
- location of plasma membrane gives it more specialized name like cell membrane, nuclear membrane etc.
Phospholipid – primary molecule in the cell membrane consisting of two parts:
Remember the Triglycerides!!!
What’s the difference between them and a phospholipid?
Why do we need a “bilayer”? Why not a single later of phospholipids?
Double layer allows:
•
All hydrophobic parts ____________________________
•
All hydrophilic parts _____________________________
WHAT ELSE IS IN THE MEMBRANE???
•
Plasma membrane also contains:
•
Proteins
•
Cholesterol
•
Carbohydrate chains
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Bio H – The Cell
Why proteins?
•
___________________________________________________________________________________________
___________________________________________________________
In other words, some molecules can sneak through the phospholipids themselves (diffusion). Others need a
specialized Protein “tunnel” to pass through. Some tunnels required ATP (active transport) while others do not
(facilitated diffusion). The movement of water is a type of diffusion, but is called OSMOSIS.
Why Cholesterol?
•
___________________________________________________________________________________________
___________________________________________________________
Why Carbs?
•
___________________________________________________________________________________________
___________________________________________________________
Fluid Mosaic Model – Theory explaining the makeup of the plasma membrane
-
Fluid because:
-
Mosaic because:
Membrane acts as a _______________________ barrier (think bouncer!)
- some stuff passes right through the phospholipids themselves:
_____________________________________ (O2, N2)
_____________________________________ (CO2)
some stuff won’t, these need membrane proteins to help them in or out of the cell:
- __________(Na+, Cl-, K+, Ca++)
- ________________________________ (Sugars, Amino Acids)
Wáter , because it is polar, uses proteins most of the time. In extreme conditions, a small amount of water (because it
is so small and it is polar, but NOT an ion) can pass through the bilayer as well.
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Bio H – The Cell
Factors that affect
permeability:
A
little
H2O
Now known that small polar
H20
H20
molecules usually pass through aquaporins (proteins) as well.
There are two general categories of transport:
1. Passive transport: The easy way; no energy required; molecules flow naturally across the membrane “downhill”
________________________________________________________________________________________
2. Active Transport: the hard way; energy required; molecules are “pushed” across the membrane “uphill”
__________________________________________________________________________________________
Both rely fundamentally on _____________________________
- the natural movement of atoms in space.
- Atoms and molecules are in constant random motion.
- collisions cause molecules to spread out as much as possible
THREE TYPES of Passive Transport in cells (diffusion, facilitated diffusion, osmosis) :
1. Diffusion: ________________________________________ _________________________________________
___________________________________________________________________________________________
–
Concentration Gradient = differences in Concentration through a space;
* Think about this: as you sit in your living room, you suddenly detect the faint smell of baking cookies.
You get up and as you walk toward your kitchen the smell gets stronger because the scent particles are
more concentrated. The difference in scent from the living room into the kitchen is a concentration
gradient of scent particles. Molecules naturally move down their gradient (from high to low). Active
transport moves them against their gradient (low to high)
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Bio H – The Cell
2. Facilitated Diffusion : ______________________________________________________________________________
_________________________________________________________________________________________________
- Glucose enters the cell via Facilitated Diffusion
•
DIALYSIS: Separation of particles based on their ___________________.
–
EX: Diabetics must go through a medical procedure called dialysis to clean their blood if their kidneys
stop working. Tubing has different size pores to block certain sized molecules.
–
Still relies on concentration gradient, but if something is too big, it will not move through pores EVEN if
diffusion should happen
Additional Notes: Facilitated diffusion (in class discussion)
Osmosis (term used to talk about movement of WATER ONLY: ______________________________________
___________________________________________________________________________________________
_________________________________________________________________________________________
Think of the water as trying to dilute the more concentrated side(side with more solute)
to make the two sides the same concentration
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Bio H – The Cell
TONICITY –term used to compare the concentration of one solution to another ; ________________________________
***Water always moves from the area that is hypotonic (less solute) to the area that is
hypertonic (more solute) ***
Examples: For each situation below, label the beaker AND the cell with the words “hypotonic” “hypertonic” or
“isotonic” and then draw an arrow showing where the water goes.
Effects of Osmosis on plant vs. Animal cells
If the cell is
floating in a 
Animal cell
Hypertonic solution
Hypotonic solution
Isotonic solution
Water moves _____________
The cell _________
This is called:
Water moves _____
The cell _________
This is called:
Water moves _____
The cell _________
This is called:
Plant
Water moves _____
The cell __________________
Water moves _____
The cell _________
This is called:
Water moves _____
The cell _________
This is called:
This is called:
Turgor pressure in plants (what is it?) :
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Bio H – The Cell
TRANSPORT THAT REQUIRES ENERGY
-
1. Active transport: move molecules ____________ their concentration gradient from ______________ to
___________.
Requires: ________________________________________________
EXAMPLE: Ion pumps:
2. VESICLE Transport: Bulk transport of large objects not individual molecules; Involves
____________________________ creating a _______________________________ called a vesicle. Requires
ATP to make the vesicle
TWO TYPES
Exocytosis: vesicle transport out of cell;
o Example:
-
Endocytosis: vesicle transport into the cell; two types
o Phagocytosis:
o
Pinocytosis:
o
Fun facts about endocytosis:

1. _______________________________________________________________________________

2. _______________________________________________________________________________
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