In awe of God’s Creation – The Workhorse of the Cell: Kinesin

Pentru traducere automata, fa click aici – Romanian

Animation of kinesin walking on a microtubule – Photo credit wikipedia

Masterpieces of microengineering, kinesins are motorized transport machines that move cellular materials to their correct locations in the cell so they can perform their functions. Kinesins have two feet, or „globular heads,” that literally walk, one foot over another. Known as the „workhorses of the cell,” kinesins can carry cargo many times their own size.

„Cells are full of specialized components that perform functions vital to their existence. But, how do these components get to the right locations, inside the cells to perform their functions? For larger components, a transportation system is needed. Meet the Kinesin- masterpieces of micro engineering. Kinesins are miniaturized motor machines that carry cargo from one part of the cell to another, walking along, self assembling highways called micro tubules.

Known as the work horses of the cell, kinesins have two feet or globular heads that literally walk, one foot over another along the microtubule pulling the cargo to its destination. Each foot possesses two special locations called binding sites that interact with other molecules. One site attaches to the micro tubule and the other binds with ATP, the energy molecule of the cell. When one foot binds with ATP and uses its energy, the foot flips over, resulting in a walking motion. Each foot has a short neck which  which is connected to a coil of a long necked stalk. At the end of the stalk is a fan shaped tail which holds tightly to the cargo being transported. Kinesins can carry cargo that are many times their own size.

Sometimes, a kinesin is in danger of getting stuck on the micro tubule highways because of blockages caused by other cellular components. To get around some of these obstacles multiple motor proteins may be used to carry a single piece of cargo, together providing enough force to break free. Kinesins, typically walk away from the center of the cell and the wall of the cell’s periphery. The kinesin’s two feet work together efficiently, with one foot holding fast to the micro tubule, while the other releases itself and takes a step forward. This coordinated step wise movement allows kinesin’s motors to walk at least 100 steps per second, moving 8 nanometers per step. When not carrying cargo, kinesins can shift to energy saving mode to conserve fuel until the next job.

The Kinesin plays a vital role in many cellular processes, not just transporting materials, but also aiding cell replication. The walking kinesin molecular machine, another example of intelligent design.

Cum functionează o celulă ?

O scurtă prezentare video a principalelor părţi componente ale celulei şi rolului funcţional al acestora. Veţi afla despre sinteza proteinelor, transportul lor la nivel celular, dar şi cum se produce energie în interiorul mitocondriilor şi cloroplastelor.

Structura celulei

INTRODUCERE

Articolul de faţă inaugurează o serie de articole care îşi propune descifrarea câtorva dintre cele mai importante componente şi mecanisme din interiorul acestei fascinante maşinării care este celula. Deşi vom vorbi despre celule în ansamblu, vom face câteva referiri şi la cazul particular al celulelor plantelor, în încercarea de a lămuri mecanismul fotosintezei. Vom vorbi despre mecanismeletranscripţiei şi translaţiei, despre reciclarea proteinelor şi transportul acestora în interiorul celulei, despre ATP şi mecanismele de producere a energiei la nivelul mitocondriilor, despre aşa-numitarespiraţie celulară şi lanţul transportor de electroni, dar şi despre alte procese biologice care se petrec la nivelul celulei.  Este momentul să ocupăm locuri într-unul din submarinele noastre celulare şi să începem cu un tur virtual al acestui fascinant microunivers.

 CITESTE in intregime AICI:

http://www.scientia.ro/biologie/71-co…

Credit: http://vcell.ndsu.nodak.edu/ VIDEO by Scientia.ro

 

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