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Monday 1/9/12
AIM: How is the structure of the plasma
membrane related to its function?
DO NOW: In complete sentences, explain
why every cell has a cell membrane.
Homework: Take home cell questions 120
DO NOW ANSWER
The cell membrane regulates what enters
and leaves the cell
Construction of the Cell
Membrane Wisconsin Online
How is the cell membrane
constructed?
The cell membrane
Plasma membrane
Phospholipid bilayer
2 layers of
phospholipids
Embedded with
proteins and
cholesterol molecule
Functions of the cell membrane
Helps to maintain balance or homeostasis
within the cell
Boundary between cell and its
environment
Selectively permeable: allows some to
pass and others are kept out
Phospholipid
Hydrophillic heads
Hydrophobic tails
Fluid Mosaic model
Individual phospholipids
are not bonded
Fluid because
phospholipids move
within the membrane
At the same time,
proteins in the
membrane also move
among the
phospholipids
These proteins create a
mosaic model
Why is it important for the
membrane to be partly
hydrophobic and partly
hydrophillic?
Tuesday 1/10/12
AIM: How is the cell membrane a fluid
mocaic?
DO NOW: 1- List the other two names for
the cell membrane
2- Explain the difference between
hydrophillic and hydrophobic
HOMEWORK: Take home test 21-40. ALL
OF IT MUST BE DONE BY TOMORROW!
Water soluble at the outer surfaces and
insoluble at inner surfaces. H bonds form
between water and hydrophillic heads
Why does the membrane need
cholesterol?
Helps stabilize the membrane
Help the hydrophobic tails move
What is the difference between an
integral and peripheral protein?
Peripheral proteins: only sit on
the surface of the membrane
Integral protein: extend
through both layers of
phospholipid bilayer
Membrane proteins
Fibrous proteins: receptors
Glycoproteins: cell to cell recognition or
identification
Pore proteins: passive transport
Channel proteins: active transport
Glyco protein
Glyco: tells me that it
is part carbohydrate
Protein: part protein
How does the structure of the
membrane relate to its function?
1- hydrophobic tails create a barrier
between inside and outside of the cell
2- hydrophillic heads allow small water
soluble molecules to bond to the membrane
3- cholesterol creates small gaps for the
molecules to “sneak” across the membrane
4- Membrane proteins help molecules move
in and out of the cell
5- Glycoproteins allow the cell to rcognize
and be recognized by other cells
Why is the plasma membrane
selectively permeable?
Wednesday 1/11/12
AIM: How does the plasma membrane
regulate movement of molecules into and
out of the cell?
DO NOW: In complete sentences explain
what you would do in the following
situation: You are at a dance that contains
100 kids within 1 hour the dance fills up
with 800 kids and you can hardly move.
What would you do and why?
Construction of the Cell
Membrane Wisconsin Online
How do molecules move across
the plasma membrane?
Lipid soluble molecules cross the
membrane with no help
Other molecules use membrane
proteins
Transport
Passive: molecules move from a high to
low concentration
Active: molecules move from low to high
concentration
Thursday 1/12/12
AIM: How do molecules move across the
cell membrane?
DO NOW: List the parts of the cell
membrane
Homework: 1- Work on topic 2 of the
midterm review
How does the concentration
gradient determine if molecules
will cross the cell membrane
passively or actively?
Transport across the membrane
cytoplasm has different
molecules and ions.
Some easily pass through
the plasma membrane
into the cell.
These include water,
oxygen and glucose
molecules, and sodium
and chloride ions.
Passive Transport
Small lipid soluble molecules move from a
crowded area to a less crowded area
Down the concentration gradient
– High concentration (lots of molecules) to low
concentration (less molecules)
No energy is required
Size and solubility of molecules determine
its ability to cross the membrane
Solubility= what a molecule can dissolve in
Passive transport
Passive transport
Simple diffusion
Osmosis
Facilitated diffusion
Diffusion
Movement is driven
by concentration
gradient
Molecules move from
an area of high
concentration to low
concentration
Solute concentration
is equal
http://www.indiana.edu/~phys21
5/lecture/lecnotes/lecgraphics/di
ffusion2.gif
http://highered.mcgrawhill.com/sites/0072495855/student
_view0/chapter2/animation__how
_diffusion_works.html
Facilitated diffusion
Some molecules are
too big to passively
diffuse
So they need the help
of carrier proteins
Transport is still
driven by a
concentration
gradient
What are the different types
of transport?
Passive and active
How are passive and active
transport different?
Passive: driven by
concentration gradient
Active: driven by ATP
Osmosis
Simple diffusion of
water
From an area of
higher
concentration to a
region where they are
in a lower
concentration
Isotonic: equal movement of water
into and out of cell
Hypotonic solution: net water
movement into the cell
Hypertonic: net movement of water
out of the cell
Aim: Why does the cell use energy to move
molecules across the cell membrane?
Do Now: Use your table from yesterday or
create a new table organizing the osmotic
environments and the flow of water in each. In a
third column of your table, draw a picture of each
using an x to represent solute molecules and o
to represent water molecules.
How does the concentration
gradient determine the
direction of molecule
movement across the cell
membrane?
Active transport
Movement of substances against a
concentration gradient
From low to high
Needs energy
Membrane proteins use energy to move
individual molecules
How does active transport differ
from facilitated diffusion?
AIM: How does the cell use energy to
transport molecules across the plasma
membrane?
DO NOW: Use the picture displayed to
explain the process:
How is active transport different
from passive transport?
Passive transport does
not need energy to move
molecules from high to
low concentration
Active Transport uses
energy to move
molecules against the
concentration gradient
Why is active transport necessary
for homeostasis?
Certain molecules need to enter or leave
the cell against their concentration
gradient
Active transport
Endocytosis: cell uses energy to carry
molecules inside
Exocytosis: remove contents from the cell
Ion pumps
Co-transport
Active transport
Endocytosis: intake of
particles or fluids in to
the cell
Pinocytosis: cell
drinking
Phagocytosis: cell
eating
Phagocytosis in an ameba
Ion Transport
Cotransport
movement of 2
solutes together
often moves 1 solute
passively & other
actively
Assessment
In your notebooks draw the picture
depicted below and explain how molecules
move in the direction of the arrows