Active transport

                       Active transport:

§ Cell has the continuously translocation of K+ ions , into the cell by active transport mechanism at the expense of metabolic energy.

§ Most of the inorganic substances or ions , uncharged particles like, amino acids , and carbohydrates are actively transported across the membrane.

§ Cell always intake the essential nutrients from the outside , many cells equilibrium of diffusion can be adjusted by coupling energy yielding reaction, so the cells are able to translocates solute or metabolite against the concentration gradient.

For eg: movement of Na+  and K+ ions pump.

§ATP DRIVEN ACTIVE TRANSPORT:

§ Na+ and k+ pump : In all cell membrane having a high content of k+ ion at the inner side and high Na+ ions at the outer side of cells, so here these are pumped against their concentration gradient. 

§ Here integral membrane protein is Na+ and k+ ATPase.

§ Na + and k+ ATPase exist in hetero tetramer  form . Its having  two subunits, α ‌and β and it also  exist in dimer form. On Hydrolysis  of ATP, gives ADP+ iP and protein changes its conformation transport 3 Na+ ions outside and 2K+ ions at the inside the cell membrane , against their concentration gradient these are pumped  at the opposite direction , so its required energy.

§ When the hydrolysis of ATP is not done then the transport of molecules is not done so its also called the coupling mechanism.

LOW DRIVEN ATP ACTIVE TRANSPORT: The molecules are transported across the membrane via coupled with the ions[ Na+ and H+ ions] 

Ø For eg: glucose is diffused by simple diffusion or via facilitated mechanism but in intestine and kidney glucose is absorbed against the concentration gradient  by an active transport system .

Ø  glucose molecules is release into the cell against concentration gradient  by the protein conformation change , after  release the glucose , protein pick up the Na+ ion  and pump them out side the cells to balance the ions concentration.

Ø Glucose is also transported into the blood stream by  diffusion.

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