Download Cell Membrane and Transport

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May 3, 2016
 Objective:
 To
create a model of the cell membrane
 To explain the structure of the cell
membrane
 Journal: What
does it mean to have a phobia
of something? What is an example of a
phobia?
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Key Terms
What
do you think are the
definitions of the following words?
Hydrophobic
Hydrophilic
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Key Terms Defined
 Hydrophobic:
 Molecules
repel and try to stay away from
water
 Hydrophilic:
 Molecules
are attracted to and tend to be
found next to water
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Phospholipids
 The
structure of the phospholipid molecule
generally consists of two nonpolar
hydrophobic tails and a polar hydrophilic
head.
+ Cell Membrane Structure
 Phospholipids
form a
Phospholipid Bilayer
 Phosphate groups =
outside
 Fatty acid tails = middle
 Occurs
because of the
locations of the water
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Structure Determines Function
 The cell
membrane structure helps it regulate
what can and cannot pass through the
phospholipid bilayer because it is selectively
permeable
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What can pass through the membrane?
 Small,
nonpolar substances pass through directly
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Other Ways to Pass Through the
Phospholipid Bilayer
 Membrane
proteins to allow specific
substances across the membrane at
specific times
 Membrane
proteins can be found on top of
or within the phospholipid bilayer
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Types of Membrane Proteins
+ Receptor Proteins
 Found
on the outside of your cells
 Sense surroundings
outside the cell
by binding substances
Cell-Surface
Proteins
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 Similar to a
nametag
 Identify each type of
cell
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Transport Proteins
 Allows certain
necessary substances that cannot
pass through the cell membrane into and out of
the cell
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Transport Proteins
 Channel
Proteins: Serve as a tunnel that allow
SPECIFIC substances through
 Carrier
Proteins: bind specific substances on
one side of the cell membrane, changes shape
and allows the substance out on the other side
of the cell membrane
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
http://www.youtube.com/watch?v=LKN5sq5dtW4
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May 4, 2016
 Objectives:
 To
differentiate between osmosis and diffusion
 To describe how molecules can move down a
concentration gradient
 Journal:
 What
types of molecules can move directly
through the cell membrane?
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Cell Transport
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Passive Transport Vocabulary
 Equilibrium
 Concentration
 Concentration
 Diffusion
Gradient
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Types of Transport
 Passive
 Active
Transport
Transport
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Passive Transport
 When
substances diffuse across the cell
membrane down their concentration gradient
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Types of Passive Transport
 Simple
Diffusion
 Facilitated
 Osmosis
Diffusion
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Simple Diffusion
 Substances
pass directly through the
phospholipids from an area of higher
concentration to an area of lower concentration
 Small,
nonpolar substances only
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+ Facilitated Diffusion
 Substances
that cannot pass directly through
the membrane diffuse through protein channels
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Osmosis
 Facilitated
diffusion of water
through aquaporins
 Allows
the cell to maintain
water balance
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Predicting Water Movement
 The
direction the water moves depends on the
concentration of the cell’s environment
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Hypertonic
 Water
 There
moves out of the cell so the cell shrinks
is more solute outside the cell than
inside the cell
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Hypotonic
 Water
moves in
 There
is more solute inside the cell than
outside the cell
 Cell
gains water and expands
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Isotonic
 There
is the same concentration of water inside
the cell and outside the cell
 Equilibrium
 Cell
is reached
stays the same size
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May 6, 2016
 Objectives:
 To
differentiate passive transport from active
transport
 To describe how active transport moves
molecules
 Journal:
 How
is active different than passive?
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Active Transport
 Transport
of substances against their
concentration gradients
 Requires
 Uses
energy (ATP)
carrier proteins
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Sodium-Potassium Pump
 Three
sodium ions are pumped out of the cell for
every two potassium ions brought inside
 Requires
 Prevents
energy
sodium from building up inside the cell,
which would cause the cell to burst due to osmosis
bringing in too much water
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Endocytosis
 The
movement of large substances into a cell
using a vesicle
 The
cell membrane forms a pouch around the
substance that closes and then pinches off
inside the cell
 Pinocytosis: also known as cellular drinking,
engulfing liquid particles
 Phagocytosis: engulfing solid particles
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Exocytosis
 The
movement of large
substances out of a cell
using a vesicle
 Vesicles
inside the cell
fuse with the cell
membrane and are
released outside the cell
 Used
to remove waste
products