Name:_______________________________ Date:____________ Class:____________________
Cell Membrane and Cell Transport
Guided Notes
Cell Membrane
The composition of nearly all cell membranes is a double-layered sheet called a _____________.
The _____________________ gives cell membranes a flexible structure that forms a strong
barrier between the cell and its surroundings. _________________________________________
______________________________________________________________________________.
Structure of Cell Membrane
Structure of a phospholipid
Water loving - ______________________ heads
Head is made of an alcohol and a phosphate group
Water hating - ______________________ tails
Tail consists of two fatty acids
Maintains ____________ for the cell by allowing waste and other products to
leave the cell.
_____________________ – allows only some
materials in and out of the cell.
______________________ move freely across the cell's membrane.
The Cell Membrane is also called a “The Fluid Mosaic Model”
– Because the membrane is ________________ and the lipids move
_________________________. (like water molecules move in the currents of a lake).
– Also because proteins create a “______________” or pattern on the surface of the
membrane.
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 Another type of lipid in the cell membrane is ____________________ that makes the
membrane more fluid.
 Embedded in the phospholipid bilayer are ____________________ that also aid in diffusion
and in cell recognition.
 Proteins called _________________ proteins go all the way through the bilayer, while
__________________proteins are only on one side.
 Large molecules like ____________or_____________ use proteins to help move across cell
membranes.
 Some of the membrane proteins have carbohydrate chains attached to help cells in recognize
each other and certain molecules.
Passive Transport- _____________________________________________
Does _______________________.
Three Types:
– Diffusion
– Facilitated Diffusion
– Osmosis
Diffusion
 As a result, the ______________________________________________________________
___________________________________________________________________________
 EQUILIBRIUM- when the molecules are even throughout a space.
 Diffusion depends ____________________________________________________________
____________________________________________________________________________
Facilitated Diffusion
 Movement of large molecules across the cell
membrane using __________________!!
 Cell membranes have ________________ that
act as carriers, making it easy for certain
molecules to cross.
 Each channel is specific for 1 type of molecule
 facilitating, or helping, the diffusion of
molecules across the membrane, and this is
called _________________________.
Osmosis
 ______________________________________________________________________________
______________________________________________________________________________.
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Three Types of Solutions
 Isotonic
 Hypotonic
 Hypertonic
 Recall a Solution = Solute + Solvent
 Solute – substance being dissolved
 Solvent – substance that does the dissolving
Isotonic Solution
“ISO” means same
 If the concentration of solute (salt) is equal on both sides, the water will move back and forth
equally.
Hypotonic Solution“HYPO” means less
 There are less solute (salt) molecules in the solution so water will move into the cell.
 Cell gets larger and could burst and die.
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Hypertonic Solution“Hyper” means more
 There are more solute (salt) molecules in the solution, so the water is sucked out of the cell.
 Cell shrinks, causes cell to die.
Active Transport
 ________________________ b/c materials are moving _____________ the concentration
gradient.
 Molecules from an area of __________ concentration to __________ concentration.
 The active transport of small molecules or ions across a cell membrane is generally carried out
by transport proteins or “pumps” that are found in the membrane itself.
 Larger molecules and clumps of material can also be actively transported across the cell
membrane by processes known as ___________________________________.
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Types of Active Transport
 Endocytosis- moving large particles INTO the cell by the cell membrane engulfing them.
–
Phagocytosis: engulf large FOOD particles
–
Pinocytosis: engulf large LIQUID particles
 Exocytosis – moving large particles OUT of the cell
________________ (en-doh-sy-TOH-sis) is the
process of taking material into the cell by means of
infoldings, or pockets, of the cell membrane.
_______________ means “cell eating.” In
phagocytosis, extensions of cytoplasm surround a
particle and package it within a food vacuole. The cell then engulfs and digests it.
 __________________________ (ek-soh-sy-TOH-sis)
is the process by which cells release large amounts of
material from the cell.
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