Biology 12 – Cell Membranes & Transport
Take notes on Chapter 4 using this handout as a guide
Name ___________________
Date ____________________
Plasma Membrane Structure and Function
The plasma membrane of the cells regulates the _____________ and __________ of molecules into and out of the
cell, helping to maintain a steady internal environment. The membrane is composed of a ___________________ bilayer
into which _______________ are embedded. The description of the membrane is often referred to as the
_________________________________ model of the membrane structure. Phospholipid heads are __________________
(water-loving) and face the water both _______________ and __________________ cells. The tails are ________________
(water-hating) and face _________________ . _______________________ is present to stiffen and strengthen the
membrane, helping to regulate its fluidity.
Sketch a phospholipid molecule
“Biology style”
Sketch the lipid bilayer: include lipids, proteins, glycolipids, glycoproteins, and
cholesterol
There are a variety of different ___________________ embedded in the cell membrane, each with its own function.
These functions include
1.
2.
3.
4.
5.
Cell membrane protein composition can have major effects on the primary role of a cell in the body.
Permeability of the Plasma Membrane (How Molecules Cross the Plasma Membrane)
The membrane of a cells is __________________________ permeable, meaning that ______________ can cross the
membrane and some _________________. Transport is of two types: _________________________ and
______________________. (Table 4.1) ______________________ requires a concentration gradient to drive movement of
molecules, but ________________________________ requires use of energy (in the form of ATP) and a carrier protein.
What is meant by the term “concentration gradient?”
____________________________________________________________________________________________________
Passive Transport
(two kinds)
Definition
Definition
Requires a concentration gradient _______________________
Requires a concentration gradient and a protein channel or carrier protein
Diffusion and Osmosis
During diffusion, simple OR facilitated, molecules move from _______________ to _________________ concentration , or
___________________________________________________ until equilibrium is achieved. Then the molecules can continue
to move about, but there is ___________________ from one side to another. What types of molecules can undergo simple
diffusion through a plasma membrane?
___________
Osmosis is ________________________________________________________________________________
Look at figure 4.6. Why doesn’t the solute (dissolved molecule) exit the thistle tube?
Why does the water level in the thistle tube rise?
Define osmotic pressure: ____________________________________________________________________
__________________________________________________________________________________________
Three types of solutions (based on solute concentration)
Definition:
Definition:
Definition:
Example sketch: solution and cell
Example sketch: solution and cell
Example sketch: solution and cell
Turgor pressure happens when a plant cell is in a __________________________ solution, and water moves
____________________ the cell. The cell does not burst because of the plant’s ________________________. A red blood
cell will undergo _____________________ (shrivelling) when it is placed into a ___________________ solution, because
water moves _________________ of the cell. The general term for shrinking of cytoplasm due to osmosis is
____________________________.
Transport by Carrier Proteins
Molecules that cannot pass through the phospholipid bilayer on their own require a ______________ protein.
Carrier proteins are _______________ meaning that they can only bind to ____ type of molecule. After a carrier combines
with a molecule, the carrier undergoes a change in ______ that moves the molecule across the membrane. Diffusion along
the concentration gradient through a carrier protein is known as ________________ transport. Some examples of
molecules that rely on facilitated transport are
When the cell requires molecules at a greater concentration than in the environment, it must use carrier proteins
to move molecules into the cell against the concentration gradient. This process, which moves molecules in the
OPPOSITE direction of diffusion, is known as __________________________. This can also happen when a cell requires a
molecule to be at a lower concentration than in the environment, and will “pump” these molecules (or ions) out of the
cell. Because this type of transport is against the gradient, it requires the use of __________________. Proteins involved in
active transport are often called _______________. Once type of pump, present in all animal cells, is known as the
________________________________
Redraw and label Figure 4.9 in the space below (Showing active transport through a plasma membrane).
Exocytosis and Endocytosis
When molecules are too large to enter or exit the cell via protein carriers, they must use ______________ formation. This
requires energy and is therefore considered a form of active transport. Secretion (vesicles releasing their contents out of
the cell) is known as _________________. There are 3 forms of _______________________ (taking in materials via vesicle
formation) known as ___________________, ________________________, and _____________________________.
Active Transport
(two kinds)
vesicle formation
One type:
One type:
Example Sketch (example, taking
in an entire bacteria)
Definition
Example Sketch (example, releasing
digestive enzymes)
Example sketch
Small molecules:
“cell drinking”
Large molecules:
“cell eating”