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Cell Membranes

Cell Membranes. Anjali, Claire, Neringa. Different Parts of a Cell Membrane. PHOSPHOLIPIDS: Phospholipids are essential components of membranes – both the plasma membrane that surrounds the cytoplasm and all the membranes inside the cell. Phospholipids are remarkable in their structure.

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Cell Membranes

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  1. Cell Membranes Anjali, Claire, Neringa

  2. Different Parts of a Cell Membrane PHOSPHOLIPIDS: • Phospholipids are essential components of membranes – both the plasma membrane that surrounds the cytoplasm and all the membranes inside the cell. Phospholipids are remarkable in their structure. PHOSPHOLIPID BILAYER: • When phospholipids are mixed with water they become arranged in double layers, with the heads facing outwards and the tails inwards. This arrangement, called a phospholipid bilayer, is the basis of the membranes of cells. • It is a very stable structure, because bonds form between the phosphate heads and the surrounding water, and the tails form hydrophobic interactions or weak intermolecular interactions that are collectively strong because of the huge numbers of tails in the membrane. • Membranes are continuous structures, without edges, that are rarely perforated or torn accidentally because many interactions would have to be broken for this to happen.

  3. Proteins in a Cell Membrane: Integral Proteins: • Integral proteins are embedded into the phospholipid bilayer. Peripheral Proteins: • Peripheral proteins are attached to the surface of the plasma membrane. There are far more peripheral proteins attached to a membrane than there are integral proteins inside it. Glycoproteins: • Glycoproteins are proteins in the cell membrane comprised of short chains of sugar molecules.

  4. Functions of Cell Membrane Proteins • To recognize nearby cells and form tight bonds with them • To act as receptors for neurotransmissions • To act as channels for passive transport and pumps for active transport

  5. Phospholipids • A phospholipid is a type of lipid with a phosphate group attached to it, the phosphate group is known as the head of the phospholipid • The head of the phospholipid is hydrophilic (attracted to water) while the tail is hydrophobic (not attracted to water) • The structure is strong because: • The heads of the phospholipids form tight adhesions with surrounding water particles and with the cytoplasm inside the cell • The tails of the phospholipids form intermolecular bonds with each other, which are not so strong, but are large in number

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