Discus why hydrophilic molecule need a carrier to cross the cell membrane?

Question

Details and examples are required where neccessary.

Answer 1

The cell membrane is made of a lipid bilayer with protein molecules floating in it. Hydrophilic molecules can not penetrate the lipid bilayer, and have to go through the protein molecules. Some proteins have aqueous channel that allow certain types of molecules to pass. Some proteins have a carrier system that allow diffusion of a certain molecule, for example, glucose into the cell. These two processes are known as facilitated diffusion. There is an active transport system that requires energy. The Na+ pump is one example.

Answer 2

The interior of membranes makes for a very hydrophobic environment. That is why hydrophilic molecules usually need a carrier to transport them across the membrane.

Answer 3

The cellular membrane surrounds the protoplasm of a cellular and, in animal cells, actual separates the intracellular aspects from the extracellular ecosystem, thereby serving a function resembling that of pores and skin. In fungi, some micro organism, and vegetation, one greater advantageous cellular wall varieties the outermost boundary; in spite of the easy fact that, the cellular wall performs oftentimes a mechanical help place fairly than a place as a selective boundary. The cellular membrane additionally performs a place in anchoring the cytoskeleton to furnish shape to the cellular, and in attaching to the extracellular matrix to help group cells together indoors the formation of tissues. The barrier is differentially permeable and arranged to alter what enters and exits the cellular, for this reason facilitating the transport of fabrics mandatory for survival. The bypass of components around the membrane must be the two passive, happening without the enter of cellular potential, or energetic, requiring the cellular to apply up potential in shifting it. The membrane additionally keeps the cellular skill. specific proteins embedded indoors the cellular membrane can act as molecular indicators that enable cells to talk with one yet yet another. Protein receptors are found ubiquitously and usual overall performance to get carry of indicators from the two the ambience and diverse cells. those indicators are transduced and exceeded in a various type into the cellular. working occasion, a hormone binding to a receptor could desire to open an ion channel indoors the receptor and allow calcium ions to bypass the cellular. diverse proteins on the floor of the cellular membrane function "markers" that %. out a cellular to diverse cells. The interplay of those markers with their respective receptors varieties the muse of cellular-cellular interplay indoors the immune equipment.

Answer 4

-Membranes are Selectively Permeable:
-Hydrophobic and small molecules can cross
-Hydrophilic (polar) and large molecules excluded
-For large hydrophilic molecules, ions (eg. glucose, Na+)
-Requires protein carriers in membrane
The Krebbs cycle is a good example.
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Answer 5

The cell membrane is a phospholipid bilayer.


extracellular environment


OOOO the head is hydrophobic
| | | | | || | the tails are hydrophibic
| | | | | || |
OOOO


Since the head is the hydrophobic region, it will not allow water soluble substances to pass through it. Therefore, hydrophilic substances (water soluble substances) need a carrier to enter the cell membrabe.

Transport of water in and out of the cell occurs passively through diffusion. Diffusion of water is called osmosis.

Answer 6

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