Download Fluid Mosaic Model - Old Saybrook Public Schools

Fluid Mosaic
Model
Cell Membrane



Lipid bilayer
Protein inserted in
the bilayer
CHO chains
attached to outer
surface
Lipid Bilayer

Hydrophilic
phospholipid head


Water loving
Hydrophobic fatty
acid tail

Water fearing!
Protein inserted in the bilayer


Act as channels
Act as a pump
CHO


Attached to outer
surface
Act as “ID cards”
Immersed in liquid

Every cell contains
liquid interior


Every cell
surrounded by
liquid


cytoplasm
Extracellular fluid
The cell
membrane
separates these
solutions

REVIEW
Selectively permeable
Plasma Membrane

Permeable =
allows a substance
to diffuse
Impermeable

Impermeable =
does not allow a
substance to
diffuse
Permeable
Biological Solutions



Concentration = mass of
solute in a given volume
of solution
 Mass/volume
 Ex: 12 g/3 L or 4 g/L
Concentration gradient
 Can be varying
concentrations on
either side of
membrane
Molecules in constant
motion
High
Concentration
Gradient
High
Concentration
Low
Concentration
Gradient
Even
Lower
Concentration
Gradient
Low
Concentration
Movement Across the Membrane

Passive Transport— requires no energy
(ATP)




Diffusion
Osmosis
Facilitated transport
Active Transport— energy (ATP) required



Pump
Endocytosis
Exocystosis
Diffusion
Passive Transport



Movement of
MOLECULES from an
area of high
concentration to an
area of low
concentration
Trying to achieve
equilibrium
Does not require
energy
Diffusion Rates



Small molecules
High
temperatures
Large
concentration
gradient
Hyper
Hypo
Osmosis




How do water
molecules get
from the hose
into my cells?
Diffusion of
WATER through a
selectively
permeable
membrane
What was the
definition of diffusion?
How is osmosis
different from
diffusion?
How are osmosis and
diffusion the same?
The tonics
Hyper



Hypertonic—an area
of high solute
concentration
Hypotonic—an area of
low solute
concentration
Isotonic—two areas
of the same solute
concentration
Hypo
H2O
H2O
Hypo
Hyper
Points to remember about tonicity!


SOLUTES SUCK!
Always reference the relationship!


Ex: Side A is hypotonic to side B
Side B is hypertonic to side A
Side A
Side B
Effects of Osmosis on Animal Cells
Osmotic Pressure

Crenation-shrivels



Homeostasis



Cell bathed in
hypertonic solution
Net movement of
water out
Cell bathed in
isotonic solution
Equal movement of
water in and out
Lysis-blows up


Cell bathed in
hypotonic solution
Net movement of
water in
Effects of Osmosis on Plant Cells
Osmotic Pressure

Plasmolyzed



Homeostasis



Cell bathed in
hypertonic solution
Net movement of
water out
Cell bathed in
isotonic solution
Equal movement of
water in and out
Turgid


Cell bathed in
hypotonic solution
Net movement of
water in
Review
* remember: SOLUTES SUCK!
0.2%
0.9%
0.9%
0.9%
0.9%
20%
Crenated
Facilitated Diffusion
Passive Transport

Protein channels
(carrier protein) in
cell membrane act
as a doorway to
allow larger
molecules to pass


Ions, sugars, salts
Still moves from
high to low

Doesn’t require
ATP energy
Carrier Protein
Active Transport

Moving against the
concentration
gradient
From [low]  [high]

Requires additional
energy ( ATP )
ATP
Active Transport
Pump


Small molecules
Na/K
ATP
✔Checkpoint
Active Transport
Endocytosis/Phagocytosis/Pinocytosis




Large amounts
transported
Take material into
the cell by
infolding creating
a pocket
Pocket breaks
loose from cell
membrane to form
vacuole
Large molecules,
food, cells
ATP
Active Transport
Exocytosis



Removal of large
amounts of
material
Membrane of
vacuole fuses with
cell membrane
Contents then
forced out of cell
ATP
One more time…
Diversity of Cellular Life
Unicellular Organism

The organism is a
single cell



Maintains all the 8
characteristics of
life
Include both
prokaryotic and
eukaryotic
May live in a
colony
Multicellular Organisms

Cell are
interdependent


Many cells working
together
Cell specialization

Creates a division
of labor
Levels of organization
Biosphere
Ecosystem
Community
Population
Organism
System
Organ
Tissue
Cell
Molecule
Levels of organization
Organ
System
Organ
Tissue
Cell