2. Movement of substance across plasma membrane
Living cell carrying out life process:
a) Absorb water and nutrient
b) Excrete waste product
c) Exchange respiratory waste product
These process IMPORTANT because :
a) Maintain optimal pH value
b) Obtain nutrient for metabolism
c) Eliminate toxic waste product
d) Secrete useful substance like hormone and enzyme
Movement substance in and out via PLASMA MEMBRANE
~regulate exchange between content of cell and external envi.
4. PLASMA MEMBRANE…
Was proposed by S.J Singer and G. Nicolson (1972)
~FLUID MOSAIC MODEL
Based on this model, structure of plasma membrane
compose of phospholipids bilayer and various
type of protein molecule
5. A phospholipids is AMPHIPATHIC MOLECULE~
has both hydrophilic region and hydrophobic
region
Polar head is HYDROPHILIC (attracted to water)
while non-polar tail is HYDROPHOBIC (repelled
by water)
The interaction ~~prevent adjacent phospholipids
from packing too tightly ~more fluid
Cholesterol ~stabilize and strength the plasma
membrane, more flexible
6. PLASMA MEMBRANE
According to this model:
Phospholipids, protein and other component of membrane
are not rigid or static, but form a dynamic and fluid structure
Protein molecule embedded in phospholipis bilayer float
freely
Protein and phospholipids free to move sideways within
membrane~~FLUID CHARACTERISTIC
Various protein built into plasma membrane~form MOSAIC
PATTERN
7. THE PERMEABILITY OF PLASMA MEMBRANE
Plasma membrane ~PARTIALLY PERMEABLE @
SEMI-PERMEABLE~ certain substance can move
freely while other cannot
Membrane envelope organelles and allow certain
substance enter or leave the organelles
Eg: Visking tube, cellophane tape, egg membrane
Selective permeability depend on~~Size and
polarity
a) Small & neutral (H2O, O2, CO2), Lipid soluble
~~easily across
b) big & polar (glucose, amino acid), charge ion
~~cannot cross and need help of TRANSPORT
8. MOVEMENT OF SUBSTANCE ACROSS
PLASMA MEMBRANE
Passive
transport
•Movement of substance
from concentration to
concentration
•Move DOWN their
concentration gradient
•NOT required energy
Simple
diffusion
Osmosis
Facilitated
diffusion
Active
transport
•Movement of substance
from concentration to
concentration
•Move AGAINTS their
concentration gradient
•Required energy
9. In liquid and gases
Molecule diffuse DOWN concentrated
gradient via plasma membrane until
EQUILIBRIUM is reach
At eq. molecule continue move back and forth,
but no net change to both side
Soluble are small uncharged & molecule
dissolve in fats
(vit A, D, E, and K)
The bigger concentration gradient, the faster
PASSIVE TRANSPORT
1) Simple diffusion
10. PASSIVE TRANSPORT
2) osmosis
Passive transport in WATER
Diffusion of water (solvent) DOWN
concentration gradient via semi
permeable membrane
Water move from higher [water] ~dilute~ to a
region of lower [water] ~concentrated~ until
concentration of both side are same. Then
water molecule move at a same rate in both
direction
Eg : absorption of water by root hair of a
11. Comparison between simple diffusion and
osmosis
Similarities
•Not require energy. Kinetic energy molecule/ion that make
them move randomly
•Move DOWN concentration gradient
•Move high concentration region to low concentration
gradient until reach equilibrium
Differences
SIMPLE
DIFFUSION
CRITERIA OSMOSIS
Gaseous and water Molecule Water
Not required semi
permeable
Membrane Required semi
permeable
12. Some substance cannot cross plasma membrane
via simple diffusion
~ need help of transport protein
Move DOWN concentration gradient
Rate depend on number of transport protein
how fast it move
The solute transported by carrier protein &
protein pore
Protein pore small charge (ion) via pore in
protein
Carrier protein uncharged polar~~ can change
shape and each carrier move specific substance
PASSIVE TRANSPORT
3) facilitated diffusion
13. Movement of substance across plasma membrane
from a region of LOW concentration to region of
HIGH concentration (AGAINTS concentration
gradient)
Require work to transport against concentration so
need energy ~ATP
Perform by specific protein molecule ~~need energy
to change the shape ~~to pump or transport
EG : intake of mineral ions by root hair of plant
ACTIVE TRANSPORT