This document summarizes various transport mechanisms across cell membranes, including: 1) Passive transport mechanisms like diffusion, facilitated diffusion, and osmosis which move molecules down their concentration gradient without energy usage. 2) Active transport mechanisms like primary and secondary active transport which move molecules against their concentration gradient and require energy in the form of ATP. 3) Bulk transport mechanisms like endocytosis (phagocytosis, pinocytosis, receptor-mediated endocytosis) and exocytosis which transport larger particles and molecules into and out of cells.

1. Transport
mechanism
By Gowshika

2. Transport mechanism across the cell
membrane
The cell membrane is selectively permeable, allowing only
a limited number of materials to diffuse through its lipid
bilayer. During passive transport, materials move by
simple diffusion or by facilitated diffusion through the
membrane, down their concentration gradient.

3. Passive
transport
Is a movement of molecules across the cell
membrane without consuming energy
Substance move from higher concentration to
lower concentration without consumption of energy
Mechanism of passive transport
Diffusion
Facilitated diffusion
Osmosis

4. Diffusion
Substance tends to move from an area of higher concentration
to area of lower concentration without consumption of energy it
continues until the concentration is equal across the space (
dynamic equilibrium is reached)
Some factors that affect diffusion
Temperature
Solvent density
Solubility

5. Facilitated
diffusion
Material diffuse across the plasma membrane with
the help of membrane proteins
Transport proteins – integral proteins involve in the
facilitated diffusion and functions as either channels
or carries
Channel proteins – specific for a substance that is
being transported
Carrier Proteins – binds a substance and triggers a
change in its own shape , moving the Bound
molecule from the outside of the cell to its interior

6. Osmosis
is a process by which molecules of a solvent
pass through a semipermeable membrane from
a less concentrated solution into a more
concentrated one, thus equalizing the
concentrations on each side of the membrane.
Without consumption of energy

7. Active
transport
mechanism
Requires energy to accomplish the movement
(in the form of ATP)
Substances move into the cell against its
concentration gradient.
Requires carrier proteins
Primary active transport
Secondary active transport

8. Primary and
secondary active
transport
• Primary active transport, also called direct active transport, directly uses
chemical energy (such as from adenosine triphosphate or ATP in case of cell
membrane) to transport all species of solutes across a membrane against their
concentration gradient.
• SECONDARY ACTIVE TRANSPORT
Secondary active transport is a form of active transport across a biological
membrane in which a transporter protein couples the movement of an ion
(typically Na+ or H+) down its electrochemical gradient to the uphill movement
of another molecule or ion against a concentration/ electrochemical gradient

9. Bulk transport
• The process by which cell engulf and remove the
larger molecules and practicals
Endocytosis
• Phagocytosis
• Pinocytosis
• Receptor mediated endocytosis
Exocytosis

10. Endocytosis
the process by which cells take in substances from
outside of the cell by engulfing them in a vesicle
Phagocytosis ( cell eater)
Pinocytosis (cell drinker)
Receptor mediated endocytosis
Process by which cells absorb metabolites, hormones,
proteins – and in some cases viruses – by the inward
budding of the plasma membrane (invagination)

11. Exocytosis
• Exocytosis is a form of active transport
and bulk transport in which a cell
transports molecules out of the cell. As
an active transport mechanism,
exocytosis requires the use of energy
to transport material.

12. Thank you 💗