TRANSPORT MECHANISM ERUDITE
Mrs. Jeanie Palomillo | 1st Semester, 2nd GRADING | BIOLOGY 2024
_______________________________________________________________________
Who plays the vital role in the
transport
mechanisms
and
separate living cell from its
surroundings?
the plasma membrane as a mosaic
of
components —including
phospholipids, cholesterol, proteins,
and carbohydrates—that gives the
membrane a fluid character. Plasma
membranes range from 5 to 10 nm in
thickness.
Ans: CELL MEMBRANE / PLASMA
MEMBRANE
Transport Mechanism
Principal components of a
★ Transport Mechanism - Refers to
the collection of mechanism
that regulates the passage of
solutes such as Ions and small
molecules through biological
membranes,
membrane.
the
Plasma membrane
1. Phospholipid- composed of;
- phosphate group
- 3-C glycerol
cell
- fatty acids (saturated and
unsaturated)
★ CELL MEMBRANE
○
○
2. Proteins- integral and peripheral
It defines the cell, outlines its
borders, and determines the
nature of its interaction with
its environment.
3. Carbohydrates- glycoproteins and
glycolipids
4. Cholesterol-
It exclude some substances,
take in others, and eliminate
others, all in a controlled
quantities.
Structural Component of a
Plasma membrane
FLUID MOSAIC MODEL
as proposed by
Seymour J. Singer and Garth L.
Nicolson 1972
The
fluid
mosaic
model describes the structure of
1
TRANSPORT MECHANISM ERUDITE
Mrs. Jeanie Palomillo | 1st Semester, 2nd GRADING | BIOLOGY 2024
_______________________________________________________________________
★ 1. PHOSPHOLIPIDS - -main fabric
of the membrane
Characteristics of Phospholipids
•
Amphipathic
* HEAD
•
can form hydrogen bonds with water
•
are in contact with the aqueous fluid
both inside and outside the cell
•
Polar- makes it hydrophilic or waterloving.
•
Negative-charged. (but not all)
* TAIL
•
Molecular structure of;
Non-polar
and
hydrophobic
No-charged;
Main functions of Phospholipids
2
•
Phospholipid bilayers are critical
components of cell membranes.
•
They acts as a barrier to the
passage of molecules and ions
into and out of the cell.
•
However, an important function of
the cell membrane is to allow
TRANSPORT MECHANISM ERUDITE
Mrs. Jeanie Palomillo | 1st Semester, 2nd GRADING | BIOLOGY 2024
_______________________________________________________________________
selective passage of certain
substances into and out of cells.
Cell recognition proteins
•
Cell
recognition
proteins
are glycoproteins that
have
several
functions,
such
as
recognition of pathogens . These
proteins serve as a cell's "identity
badge" if the cells of your immune
system see a cell in your body that
doesn't
have
the
correct
glycoproteins sticking out of it.
•
It enables our body to distinguish
between our own cells and cells of
other organisms.
•
If you have low immune system,
virus or bacteria can go inside the
cell and able to copy the genetic
material and hide their viral
characteristics. With that, Immune
system cannot already
★ 2. PROTEINS (transmembrane)
•
Integral Proteins- (integrins) are
integrated completely within the
membrane structure.
- primarily for transport
- receptor function, cell
adhesion, structural
support
•
identify them and virus or bacteria
are free to destroy the cell.
Peripheral proteins- found on the
exterior and interior surfaces of
the membrane only.
primarily
recognition
for
•
MOLECULAR MIMICRY
cell
Cell specific proteins
•
The body recognizes its own
proteins and attacks foreign
proteins associated with invasive
pathogens
bacteria.
3
like
viruses
and
TRANSPORT MECHANISM ERUDITE
Mrs. Jeanie Palomillo | 1st Semester, 2nd GRADING | BIOLOGY 2024
_______________________________________________________________________
•
•
Specific proteins are valuable
markers for a variety of diseases
including microbial infections,
inflammatory response, cardiac
risk and even cancer.
Enzymes and hormones
specific proteins.
foreign cells or tissues (“non-self”).
GLYCOCALYX (“sugar-coating”)
•
are
Glycocalyx is a highly charged
layer
of
membrane-bound
biological
macromolecules
attached to a cell membrane.
•
It plays an important role to
prevent the entry of pathogens
into the cell.
•
It
is
important
for
cell
identification,
self/non-self
★ 3.CARBOHYDRATES (GLYCOCALYX)
determination, and embryonic
development.
•
CARBOHYDRATES CHAIN
•
★ 4. CHOLESTEROL
May consist of 2-60
monosaccharide units
and can be either
straight or branched.
•
•
•
It is a structural component of cell
membranes
•
It has a crucial role in regulating cell
function
•
Maintains the integrity and fluidity
of the plasma membrane
•
Dampens (make less strong or
intense) effects of temperature
Forms a special sites on the cell
surface that allow
recognize each other.
cells
Also
used
in
cell-cell
attachment to form tissues.
to
This recognition function is very
important to cells, as it allows the
immune system to differentiate
between body cells (“self”) and
4
TRANSPORT MECHANISM ERUDITE
Mrs. Jeanie Palomillo | 1st Semester, 2nd GRADING | BIOLOGY 2024
_______________________________________________________________________
and
preventing
increased
temperature
(warm)
from
increasing fluidity too much. Its
function extends in both direction.
•
CHOLESTEROL STRUCTURE
•
C27H46O (molecular formula)
•
Hydroxyl group
hydrophilic)
(polar
and
•
A central sterol nucleus made of
four hydrocarbon rings (steroid)
•
Hydrocarbon tail (non-polar and
hydrophobic)
★
Function of Cholesterol
•
Dampens
the
effects
of
temperature on the membrane.
•
It prevents lower temperature
(cold) from decreasing fluidity
5
Other functions includes organizing
clusters
of
transmembrane
proteins into lipid rafts.