Bio A – The cell
Cell Transport Note packet
Structure of the Plasma Membrane
(draw and label diagram from board)
Label the following parts in the diagram above and then briefly describe their job:
Plasma Membrane H  I Phospholipid bilayer that surrounds the cells and organelles within the cells (contains
proteins too) (Slide 4)
Phospholipids: (A)A1 is the phosphate head (hydrophilic). A2 are the two fatty acids (nonpolar, hydrophobic) (Slide 5)
If you shake phospholipids and let them settle, the heads will be attracted to water, the tails away from water, when
water is on both sides of the phospholipids, the tails will turn toward each other forming a bilayer (slide 7, 8, 9)
Proteins: (G and F) G is a channel protein (has a channel running through it) Slide 10, 11,12
Cholesterol: (E) (slide 12) Keeps membrane flexible (their webquest also said it keeps the membrane from getting too
flexible, slide set says keeps it from getting too stiff…key is…it keeps it the correct fluidity
Carbohydrates: (D) polysaccharides act as “ID tags” other cells can tell “what kind of cell” this is by its tag Slide 13
Glycoprotein (carbs attached to protein (C with D attached)
Glycolipid (B)
Review of vocab. Needed for this unit:
1.
Homeostasis: ___Maintenance of the cells internal conditions (pH, temp, water, size
2. Solution : _Homogeneous mixture____
a. Solute: _what is dissolved (this can be glucose, salts, amino acids in living things)_
b. Solvent: _The dissolver (in living things this is WATER_
Bio A – The cell
Certain things need to enter the cell, certain things need to leave: (slide 16)
In: N2, O2, CO2, water, amino acids, glucose, ions
Out: CO2, glucose and O2(plants), waste, N2, water
But remember, the membrane is selectively permeable meaning___the membrane allows SOME but not ALL molecules
into the cell. IMPORTANT: Neither the CELL WALL nor the CELL MEMBRANE can protect the cell from small toxic
molecules (like benzene!)
NOTE: CHANGE DIAGRAM BELOW. (slide 18) CROSS OUT SMALL POLAR MOLECULES. MOVE WATER OVER WITH
OTHER POLAR MOLECULES. REASON: we now know that water goes through PROTEINS. Used to think it went
through the PL bilayer.
In general, what types of molecules pass
What can pass through phospholipids of membrane?
through the phospholipid bilayer? Slide 19)
SMALL GASES (N2, O2, CO2) and
sometimes not so good things (benzene)
What types of molecules require a
membrane protein to enter? (slides 20-22)
SMALL and LARGER polar molecules
(water, glucose, amino acids
Ions like Cl, Na, K, Ca
There are two ways to move molecules in and out of the cell:
A. Passive Transport: (slide 23) Requires no energy; molecules move from high concentration to low concentration.
Molecules “roll down hill to spread out” - three types of passive transport include: ___Diffusion, Osmosis, Facilitated diffusion (look at the graphic
organizer!!!)
1. Diffusion:__movement of SOLUTE from an area of high concentration to an area of LOW concentration. Will
keep moving until the concentrations are equal (equilibrium) _
MOVES DUE TO A CONCENTRATION GRADIENT (a difference in concentration)
DIFFUSION CAN OCCUR WITH OR WITHOUT A MEMBRANE
When does it stop? __will equilibrate but solute is constantly moving (so particles move both ways across the
membrane EQUALLY when in equilibrium.
Bio A – The cell
2. Facilitated Diffusion: same as diffusion BUT _______REQUIres a transport protein (but NO ENERGY, still
moves from high concentration to low concentration) _____________________________________________
- moves things that can’t move across phospholipid bilayer on their own like Glucose (big molecules). What
does facilitated mean? It means to HELP
STUDY TO HERE FOR QUIZ
3.
Osmosis: Movement of WATER from across a membrane
- When does it stop?
-
TONICITY (tonic) – term that compares the concentration of one solution to the concentration of another
Hypotonic: ________________________________________________________________________________
Hypertonic: _______________________________________________________________________________
Isotonic: __________________________________________________________________________________
**** MOST IMPORTANT RULE***** Water always moves from _____________________________________________
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
Bio A – The cell
Outside is a 
Hypertonic solution
Hypotonic solution
Isotonic solution
Water moves ______________
Water moves ______________
Water moves ______________
The cell ___________________
The cell ___________________
The cell ___________________
This is called:
This is called:
This is called:
Water moves ______________
Water moves ______________
Water moves ______________
The cell ___________________
The cell ___________________
The cell ___________________
This is called:
This is called:
This is called:
Animal cell
Plant
B. Active Transport:
Requires energy in the form of ATP (energy molecule)
Molecules move from low concentration to high concentration
Needed to move _________________________________
Have to “push molecules up hill so they become more crowded;”
1. Active transport– molecules must be “carried” into the cell with the help of BOTH a membrane protein and
energy
2. Vesicle Transport – moving large quantities in a membrane bubble called a vesicle
Exocytosis – ___________________________________________________________________________
Endocytosis – _________________________________________________________________________
Bio A – The cell
Phagocytosis – moving solids like food; also used by our immune system to kill bacteria
Pinocytosis – moving large amounts of liquid into cell