Transportation through the cell membrane

Transportation through the cell membrane:-

Transportation of substances across the cell membrane is essential to the life of a cell. Various substances must have moved into cells because they help to support metabolic reactions.

Transportation process classified into two mechanisms:-

  1. Passive Mechanism
  2. Active Mechanism

Passive Mechanism (Diffusion) Transportation:-

It is the transportation of substance along the concentration gradient or electrical gradient or both (electrochemical gradient)is called Passive Transport.

In other words, it is the not movement of a substance from higher concentration to lower concentration, it is called Diffusion.

It is two types:-

  1. Simple Diffusion
  2. Facilities Diffusion

Simple Diffusion:- Simple diffusion is acquiring through the lipid layer and also acquire through the protein layer.

Example:-Gas exchange between alveoli and blood capillaries, oxygen diffused in alveoli to blood capillaries, and carbon-dioxide diffused from blood capillaries to the alveoli.

Facilities Diffusion:- In this type of diffusion some transport protein help in the transport of a substance.

Example:- Glucose and amino acid are transport by the facilities’ diffusion.

Osmosis:-

It is the movement of the from higher concentration to the lower concentration through a semi-permeable membrane.

In a living system, the solvent is water which moves by osmosis across the cell membrane from an area higher water concentration to lower water concentration.

Osmosis is a passive process in which water moves through a selectively permeable membrane from an area of lower solutes concentration to an of higher solute concentration.

Example:-Absorption of water by stomach and colon Re-absorption of water by tubules of the nephron.

Active Mechanism:-

Active transport is the movement of the molecule across a cell membrane against their concentration and electrical gradient.

It is an active process because energy is required for the transported protein to move solute across the cell membrane against their concentration and electrical gradient.

Active transport is of two types:-

  1. Primary Active Transport:- Transport or substance across the cell membrane against its concentration gradient by pumps. Transmembrane protein uses energy supplied by ATP. Example :- Na+,K+, ATPase pump.
  2. Secondary Active Transport:- Coupled of two substances across the cell membrane using energy supplied by the electrochemical gradient.
  • Anti-porter:- Antiporter moves ion and other ion in opposite direction across the cell membrane.
  • Symporter:- Symporter moves glucose and amino acid in the same direction across the cell membrane.

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