The document discusses transport of nutrients, ions, and macromolecules across cell membranes. It explains that the plasma membrane acts as a semi-permeable barrier that allows selective transport through passive or active mechanisms. Passive transport includes osmosis, simple diffusion, and facilitated diffusion, which move molecules down concentration gradients without energy. Active transport uses membrane proteins like ion pumps and carriers to move molecules against gradients, requiring energy sources like ATP. Transport proteins include channels, carriers, and pumps that facilitate movement of nutrients across membranes.

1. TRANSPORT OF NUTRIENTS, IONS AND
MACROMOLECULES ACROSS MEMBRANE
By
KAUSHAL KUMAR SAHU
Assistant Professor (Ad Hoc)
Department of Biotechnology
Govt. Digvijay Autonomous P. G. College
Raj-Nandgaon ( C. G. )

3. INTRODUCTION
 Plasma membrane encloses every type of cell, both prokaryotic and eukaryotic cells.

 It physically separates the cytoplasm from the surrounding environment.


 Membrane controls the entry of nutrients and exit of waste product, and generates
differences in ion concentration between the interior and exterior of the cell.

 The cell of bacteria and plants has the plasma membrane between the cell wall and
cytoplasm.


 All biological membranes including the plasma membrane and internal membrane of
eukaryotic cellsare similar in structure and selective permeability but differing in other
functions.

 CHEMICAL COMPOSITION:-
 Chemically plasma membrane and other membrane of different organelles are found
to contain proteins, lipids and carbohydrates, but in different ratios.



4. Fig.:-Structure of membrane (Biologyjunction.com)

5. TRANSPORT
ACROSS
MEMBRANE
The plasma membrane act as a semi
permeable barrier between the cell
and the extra cellular environment,
this permeable must be highly
selective.
The selective permeability of the
plasma membrane allows the cell to
maintain a constant internal
environment
Fig.:- Transport across membrane
(Biologyreference.com)

6. TRANSPORT
ACROSS
MEMBRANE
The organelles within the cell have
different internal environment from
that of the surrounding cytosol and
organelle, membrane maintain this
difference.
Transport across the membrane may
occur via the phospholipid bilayer or
by the help of specific integral
membrane proteins called permease
or transport protein.
Fig.:- Transport across membrane
(Biologyreference.com

7. PASSIVE
TEANSPORT
 It is a type of the diffusion in which an ion or molecules crossing a
membrane moves down its concentration gradients.
 No metabolic energy is consumed.


8. TYPES OF PASIVE
DIFFUTION
 1. OSMOSIS
 2.SIMPLE DIFFUSION
 3.FASILITATE DIFFUSIN

9. OSMOSIS
• The plasma membrane is permeable to water molecules.
• The to and fro movement of water molecules through the plasma membrane occurs due to the
difference in the concentration of the solute on its either side.
• The process by which the water molecules pass through a membrane from a region of higher
water concentration to the region of lower water concentration is known osmosis.
• When two compartments of different solute concentration are separated by a semipermeable
membrane
-The comportment of higher solute concentration is said to be hypertonic solution .
-The compartment of lower concentration is known as hypotonic.

10. Fig.:-Osmosis(Goldiesroom.org)

11. TYPES OF OSMOSIS

12. DIFFUSION
•Diffusion is spontaneous process in which a substance moves from a region of high
concentration to a region of low concentration.
•During simple diffusion, a small molecules in aqueous solution crosses the phospholipid
bilayer, and then dissolves into the aqueous solution on the opposite side.
• The relative rate of diffusion of the molecule across the phospholipid bilayer will be
proportional to the concentration gradient across the membrane.

14.  Substances always diffuse across a membrane from a region of
higher concentration on one side to a region of lower concentration
on the other side, but they do not always diffuse through the lipid
bilayer.
 In many cases the diffusing substance first binds selectively to a
membrane spanning protein, called a facilitative transporter that
facilitate the diffusion process.
 Facilitate diffusion, as process is called is, similar in many way to
an enzyme catalyzed reactions.

16. EXAMPLE OF FACILITATE DIFFUSION

17. Fig.Mechanism of facilitate diffusion (Mansfield.ohio-state.edu).

18. •When a molecules moves from lower concentration to higher concentration, is often
required in cells, energy input is required and the transport is describe as “active
transport”.
•Active transport is always mediated by carrier protein or pumps, although passive
transport may or may not involve carrier proteins.
•
•Ion channels are never involved in active transport they involve in passive transport
only.

19. TYPES OF ACTIVE TRANSPORT
 1.PRIMARY ACTIVE TRANSPORT
 Primary active transporter found in all living organism, require an
energy source to drive uptake of solute.
 Mammalian cell requires ATP or another nucleoside triphosphate as
the energy source
 2.SECONDARY ACTIVE TRANSPORT
 Secondary active transporters, utilize a secondary source of energy
such as a transmembrane electrochemical gradients of either
Na+(sodium motive force, SMF)or H+ (proton motive force, PMF) to
drive translocation

21. •Na+-K+-ATPase pump:-
•It is an ion pump or cation exchange pump which is driven by energy of one molecule to
export three Na+ ions outside the cell in exchange of the import of two K+ ions inside the
cell.
•Na+-K+-ATPase is a transmembrane protein of this pump.

22. Fig.:- Na+-K+-ATPase pump (Biologyreference.com)

23. CALCIUM ATPase
•Ca+ ATPase pumps Ca+ ions out of the cytosol, maintaining a low concentration of it
inside the cytosol.
•In some type of cells such as erythrocytes, the calcium pumps are located in the
plasma membrane and function to transport Ca2+ ions out of the cell.
• In contrast, in muscle cells, Ca2+-ion pumps are located in the membrane of
endoplasmic reticulum.

24. PROTON PUMP OR H+ PUMP
The lysosomal membrane contains the ATP-dependent proton pump that
transports protons from the cytosol into the lumen of the organelle.
Proton pumps also occur in mitochondria and chloroplast where they participate
in the generation of ATP from ADP.
They also cause acidification of the mammalian stomach.

25. Fig.- Proton pump (Daviddarling.info)

26. TRANSPORT OF LARGE MOLECULES BY PLASMA
MEMBRANE
Endocytosis:-
Active cellular intake of extra cellular fluid and solid is called Endocytosis.
Types of Endocytosis:-
Pinocytosis
Phagocytosis
Receptor- mediated Endocytosis

27. Fig.:-Endocytosis(bio.miami.edu)

28. Exocytosis;
Expulsion of extracellular fluid and solid out from the cell is called Exocytosis
Fig.:-Exocytosis (mansfield.ohio-state.edu)

29. TRANSPORT OF NUTRIENTS BY MEMBRANE PROTIEN
•These forms water filled opened pores across the bilayer through which specific solute
can diffuse or molecules of the appropriate size (e.g., ions) can cross the membrane.
•Channel proteins in the cell membrane forms tunnels across the membranes to move
the materials.
•They may also be open or have gates that open and close to control the movement of
the materials, called gated channel.
•Gates open close in response to concentration inside and outside the cell.
Channel Proteins

30. Carrier Proteins
Carrier protein selectively binds the small molecule to be transported and
undergo conformational change to release the molecule on the other side of
the membrane.

31. • Help to regulate cell volume.
• Help to maintain intracellular pH and ionic composition within narrow range to provide
favorable condition for metabolic activities or enzymatic reaction to occur.
• Help to concentrate metabolic fluid and building blocks of body and excrude toxic
substance.
• Membrane transport generate ionic gradient essential for excitability of nerves and
impluse.

32. •Every living cell must require from its surrounding the raw materials for biosynthesis
and for energy production and must release to its environment the byproduct of
metabolism.
•A few non polar compound can dissolve in the lipid bilayer and cross the membrane
unassisted, but for polar or charged compound or ions, a membrane protein is essential
for transmembrane movement.
•In some cases a membrane protein simply facilitates the diffusion of a solute down its
concentration gradients.
•Transport also occur against a gradients of concentration, electric charge, or both, in
which case solute must be pumped in process that requires energy.
•Small molecules across the plasma membranes is transported by protein such as
transmembrane channel, carriers and pumps.
CONCLUSION

33. Name of books Authors
Cell and molecular biology
(fourth edition) .
Gerald Karp
Principle of biochemistry.
(fourth edition)
David L.Nelson and M.Cox
Biochemistry with chemical co
relation
(sixth edition)
Thomas M. Delvin
REFERENCE
www.biologyreference.com(Encyclopedia)