Question:
1) What’s phospholipids means?
A phospholipid is an amphipathic molecule, meaning it has both a hydrophilic region and a hydrophobic region.
2) Where the protein is located?
There are integral proteins and peripheral proteins. Integral proteins penetrate they hydrophobic core of the lipid bilayer. Peripheral proteins are appendages loosely bound to the surface of the membrane, often to exposed parts of integral proteins.
2) What called a electrogenic pump?
3) A transport protein that generates voltage across a membrane is called an electrogenic pump.
Factors
1) In the fluid mosaic model, the membrane is a fluid structure with a “mosaic” of various proteins embedded in or attached to a double layer (bilayer) of phospholipids.
2) Cells recognize other cells by binding to surface molecules, often to carbohydrates, on the plasma membrane.
3) They dye diffuses from where it is more concentrated to where it is less concentrated called diffusing down a concentration gradient.
4) To pump a solute across a membrane against its gradient requires work; the cell must expend energy. Therefore, this type of membrane traffic is called active transport.
5) A single ATP-powered pump that transports a specific solute can indirectly drive the active transport of several other solutes in a mechanism called cotransport.
Summary：
Cellular membranes are fluid mosaics of lipids and proteins. Membrane structure results in selective permeability. Passive transport is diffusion of a substance across a membrane with no energy investment. Active transport uses energy to move solutes against their gradients bulk transport across the plasma membrane occurs by exocytosis and endocytosis.
Diagram
Key terms
Osmosis: the diffusion of water across a selectively permeable membrane is called osmosis.
Isotonic: the isotonic to the cell means a cell without a wall, like an animal cell is immersed in an environment.
Hypertonic: when animal cell is immersed in a solution, it means hypertonic which the cell will lose water to its environment, shrivel and probably die.
Passive transport: the diffusion of a substance across a biological membrane is called passive transport.
Plasmolysis: as the plant cell shrivels, its plasma membrane pulls away from the wall, this phenomenon called plasmolysis.
Hypotonic: if we place the cell in a solution that is hypotonic to the cell, water will enter the cell faster than it leaves, and the cell will swell and lyse like an overfilled water ballon.
Active transport: to pump a solute across a membrane against its gradient requires work; the cell must expend energy, therefore, this type of membrane traffic is called active transport.
Facilitated diffusion: many polar molecules and ions impeded by the lipid bilayer of the membrane diffuse passively with the help of transport proteins that span the membrane. This phenomenon is called facilitated diffusion.
Peripheral proteins: they are not embedded in the lipid bilayer at all; they are appendages loosely bound to the surface of the membrane, often to exposed parts of integral proteins.
Integral proteins: they penetrate the hydrophobic core of the lipid bilayer.
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