Biodiversity plays an important role inecological health as much as it does for human health. ... Ecosystem engineers aredefined as: "...organisms that directly or indirectly modulate the availability
* Channel proteins- these are proteins with a hydrophilic pore where specific ions are able to pass through the membrane. Each channel protein is specific to an ion. This is the only way ions can travel through the membrane. They are trans membrane proteins.
* Carrier proteins- these are proteins which allow larger or polar molecules through the membrane. They are trans membrane proteins.
Carrier proteins essentially “carry" signals that are not soluble in aqueous solution through the blood stream to their target cells. Carrier proteins for hydrophilic signals prevent degradation of the signal. Channel proteins are embedded in cell membranes. They often are receptors (though not always), and when activated, allow specific ions to pass through the membrane.
A channel protein is a special arrangement of amino acids which embeds in the cell membrane, providing a hydrophilic passageway for water and small, polar ions. Like all transport proteins, each channel protein has a size and shape which excludes all but the most specific molecules
The carrier protein facilitate diffusion of molecules across the cell membrane. The protein is imbedded in the cell membrane and covers the entire membrane. This is important because the carrier must transport the molecule in and out of the cell.
Answer:
The Greeks believed in the geocentric model of the universe.
According to this model, the Earth was present in the center whereas the Sun, moon, other planets etc revolved around it. According to Plato, the Earth was spherical in shape and it did not move. Greek philosophers, such as Aristotle and Plato, believed the Earth to be the center of the universe. All other heavenly bodies orbited around the Earth according to the Greek philosophers.
