Page 1
Cell Transport Notes
I.
Cell Membrane
 ____________________ & ____________________
A. Function:


_____________________________: Allows some things in the cell but not others
General rules: Small, hydrophobic/non-polar can diffuse (slip between the phospholipids)
into cell
Molecule
Examples
Can Diffuse Into Cell?
Small/ Hydrophobic
Glycerol
H2O, Carbs, Amino acids,
Nucleotides
Ions (charged particles)
B. Structure
a. Made of ______________________
b. Makes the membrane hydrophobic and nonpolar
c. Arrange in a ___________________
i. Two parts:
1.
2.
d. Contains ____________________ (to strengthen the membrane) and proteins – ONLY
ANIMALS HAVE CHOLESTEROL IN CELL MEMBRANE
e. Proteins
i. Play a variety of roles in cell membrane
 _____________________ - receives signals
 _______________________ - moves molecules across membrane
 _______________________ - act as doorways; allow ions and other polar molecules
through (ones that cannot diffuse in)
 ________________________ - act as ID tags
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Label the membrane: Phospholipid, polar head, non-polar tail, hydrophilic, hydrophobic, proteins
sugar
C. Fluid Mosaic Model
- A model used to describe the cell membrane
1. ___________________ 
Made up of phospholipids, proteins, cholesterol, etc.
2. ___________________ -
II.
Transport Terms
a. Concentration gradient- _______________________________________
b. Molecules naturally move from a __________ concentration to a ________ concentration
i. Does not require energy
c. Molecules will move until they achieve EQUILIBRIUM- the equal distribution of particles in a
given space (don’t stop moving even after reaching equilibrium)
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III.
Passive Transport
 _______ energy needed
 Caused by a concentration gradient
 Molecules move from ________ to _______ ___________ THE GRADIENT
 GOAL=_______________________
 Movement continues equally in both directions
A. 3 Types
1. Diffusion
a. The movement of ______ particle from high
concentration to low concentration.
b. Only ___________, _______________ and
uncharged molecules can diffuse across the
cell membrane.
c. Example: Alveoli in lungs
i. Diffusion of O2 & CO2
2. Osmosis
a. Diffusion of ____________ across a selectively
permeable membrane
b. Induces ____________ _______________ in plants
i. Water from roots fills central vacuolepushes cell mem. against cell wall  keeps
plants upright
c. Solutions:
i. *** When a solution is referred to as “10% solution,” that means the solute makes up
10% of it. The other 90% is water.
ii. *** Water moves to where there is a low concentration of water (but a high
concentration of solute).
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More H2O = less solute
Less H2O = more solute
iii. Isotonic Solution
3. Iso = Same
4. ___________ amount of solute inside and outside of
cell (in solution)
5. Constant movement of water in both directions
6. Cell does not change _____________
i. Hypertonic Solution
1. __________ solute & less water _____________ of cell (in
solution)
2. Cell can recover
3. Water flows ________ of the cell and the cell shrivels up;
turgor pressure decreases (cell shrinks)
4. Plant – wilts, ______________________
5. Animals- shrinks; ____________________
a. Ex. Salt water
ii.
Hypotonic Solution
1.
_________ solute and ___________ water outside of cell
2.
Animals:
i. Cells can burst (_________________) b/c no cell wall
ii. Cell CANNOT recover if bursts
3.
Plants:
i. ________________ fills with water
ii. Turgor pressure increases
iii. ________________________ protects from bursting
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3. Facilitated Diffusion
a. Movement of particles, from ________ to __________ concentration, across the cell membrane with the
aid of a special membrane __________________.
b. For ______________ or _______________ particles that cannot diffuse through membrane
c. Requires a channel protein
d. Remember – passive transport. NO ENERGY NEEDED
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IV. Active Transport
 Cell _________________ to power this process (ATP)
 Molecules move ______________ (up) their concentration gradients (from ________ to __________)
 Ex. Sodium-potassium pump
 Ex: Endocytosis and Exocytosis
 Goal: Achieve _______________________
 Homeostasis- maintain a constant ______________________ in body
 Example: When running  Sweating, increased heart/breathing rate, increased thirst
A. Bulk Transport
o Transporting large quantities of solutes/products into or out of the cell
Two Types
1. Exocytosis
o Transport bulk materials OUT of the
cell enclosed in vesicles
2. Endocytosis
o Transport bulk materials into the
cell enclosed in vesicles
o Two Types:
o Phagocytosis - “Cell Eating”
o Taking in large solid
particles
o Pinocytosis - “Cell Drinking”
o Taking in large amounts of
dissolved solutes (liquids)
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B. Protein Pumps

Proteins act as pumps to move solutes in and out of cell by ________________________________

For many types of molecules (often large molecules/ ions and protons)

Requires ______________ – ATP (up gradient)

Goal: ____________________ – allows nerve cells to send messages
1. Sodium Potassium Pump (Na/K)

Type of protein pump that changes shape

Purpose: Moves Sodium ________ of and Potassium ____________ the cell against the
concentration gradient
o Found in nerve cells
o Creates changes in voltage in the cell (b/c of the charges on the ions)
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Transport in Pictures
1. Label the parts of the cell membrane (word bank: phospholipid, phosphate head, fatty acid tail, hydrophilic,
hydrophobic, membrane protein, carbohydrate)
2. Label the processes using the word bank, (terms may be used multiple times).
WORD BANK: Osmosis, Diffusion, Facilitated Diffusion, endocytosis, exocytosis, protein pump.
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3. Label the picture below using the word bank (hypotonic, hypertonic, Isotonic, animal cell, plant cell, cytolysis,
plasmolysis, turgor pressure)
a. Which process is shown in the image above?
b. Why do animal and plant cells react differently?
c. Place a star next to the normal state of an animal cell and of a plant cell.
VOCAB TO KNOW
Diffusion
Equilibrium
Homeostasis
Osmosis
Passive transport
Endocytosis
Selectively permeable
Active transport
Exocytosis
Bilayer
Isotonic
Phagocytosis
Crenation
Hypotonic
Pinocytosis
Fluid Mosaic
Hypertonic
Plasmolysis
Concentration gradient
Facilitated Diffusion
Cytolysis
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CELL TRANSPORT
Passive Transport
Active Transport
Need energy?
Need energy?
Moves from __________ to ___________
Moves from __________ to ___________
__________________ gradient
__________________ gradient
Goal:
Goal:
1.
1. Protein Pump
Movement of:
Need:
Types of molecules:
Example:
2.
2. Bulk Transport
Movement of water across a
Movement of:
3 Solutions:
1.
2.
3.
Moves
substances
OUT of cells
Moves
substances
INTO cells
3.
Needs a
Type of molecules:
Moves:
Moves:
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Cell Transport Study Guide
1. Complete the following chart.
Type of
Transport
Active or
Passive?
Diffusion
Osmosis
Facilitated
Diffusion
Endocytosis
Exocytosis
Protein
Pump
Direction of
Movement
Does it require
energy?
Type of
molecule
moving
Goal
(equilibrium or
homeostasis?)
Other defining
characteristics
Answer the following questions:
2. Explain the terms homeostasis & equilibrium–
3. What does it mean to go up the concentration gradient? To go down the concentration
gradient?
4. What do the terms crenation, plasmolysis and cytolysis refer to?
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5. Label the following pictures:
Types of Osmosis
Hypertonic
Isotonic
Label the picture to
show
 Direction of the
movement of
water using
arrows
 Higher solute
concentration
inside or outside?
 Higher solvent
concentration
inside or outside?
How does this affect an
animal cell? Describe or
sketch
How does this affect an
plant cell? Describe or
sketch
Label the following:
Phospholipid
Proteins
Carbohydrate
Cholesterol
Hydrophilic
Hydrophobic
Head
Tail
Hypotonic
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Cell Membrane
1. What molecule makes up most of the cell membrane?
2. What other molecules can be found in the cell membrane?
3. List the 4 types of proteins found in the cell membrane, as well as their
functions.
4. Explain why the cell membrane is called both fluid and mosaic.
5. Explain which molecules cannot pass through the membrane and explain
why.
6. Explain which molecules can pass through the membrane and explain
why.
7. What does it mean for the membrane to be selectively permeable?