2. Membrane Transport
- Refers to the collection of
mechanism that regulate the
passage of solutes such as
ions and small molecules
through biological
membranes which are lipid
bilayers that contain proteins
embedded in them.
3. Plasma Membrane
- Plays a vital role in the
transport mechanism in cell.
3 Components
1. Lipids- makes the semi-
permeable barrier
2. Proteins- involved in the
cross-membrane transport
3. Carbohydrates- decorates
both the protein and lipids
5. KEY TAKES OF THE FLUID OF THE CELL
MEMBRANE
• Phospholipids in the Plasma
membrane can move within the
bilayer (Lateral & Flip-flopping)
6. •Most of the lipids, and some
proteins, drift laterally
•Rarely does a molecule flip-flop
transversely across the membrane.
•As temperature cool, membrane
switch from fluid state to a solid
state.
•Membranes rich in unsaturated fatty
acids are more fluid than those rich
in saturated fatty acids.
7.
8. •The steroid cholesterol has
different effects on the
membrane fluidity at different
temperature.
•At warm temperatures
cholesterol restrains
movements of phospholipids.
•At cool temperatures
9. COMPONENTS LOCATIONS FEATURE/FUNCTIONS
Phospholipids Main fabric of the membrane • The most abundant lipid
in the plasma membrane
and they are amphipathic
molecules.
Cholesterol Tucked between the
hydrophobic tails of the
membrane phospholipids
• Dampen effects of
temperature
Integral Proteins Embedded in the phospholipid
bilayer; may or may not extend
through both layers
• Transport of substance
through membrane
Peripheral Proteins On the inner or outer surface of
the phospholipid bilayer, but not
embedded in its hydrophobic
core
• Cell recognition
Carbohydrates
Chains
Attached to proteins or lipids on
the extracellular side of the
membrane (forming
glycoproteins and glycolipids.
• Cell recognition
• Effective interaction with
aqueous environment
10. Terminologies
1.Amphiphilic or Amphipathic
- Molecule possessing a polar or charged area
and a nonpolar or unchanged area capable
of interacting with both hydrophilic and
hydrophobic environments.
2. Fluid mosaic model
- Describes the structure of the plasma
membrane as a mosaic of components
including phospholipids, cholesterol, proteins,
glycoproteins and glycolipids resulting in a fluid
character.
11. 3. Glycolipids & Glycoproteins
- Combination of carbohydrates and
lipids
4. Hydrophilic
- Molecules with the ability to bond with
water “ Water-loving”
5. Hydrophobic
- Molecules that does not have the
ability to bond with water; “ Water-
hating”
12. 6. Integral protein
- Protein integrated into
membrane structure that
interacts extensively with the
hydrocarbon chains of membrane
lipids and often spans the
membrane; these proteins can be
removed only by the disruption of
the membrane by detergents.
13. 7. Peripheral protein
- Protein found at the surface of
a plasma membrane either on
its exterior or interior side;
these proteins can be
removed(washed off the
membrane) by a high-salt wash
