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8 Cards in this Set

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What are some of the functions of cell membranes?
the plasma membrane acts like a gatekeeper, allowing only specific substances in or out and passing chemical messages from the external environment

It selectively Isolates the cell's contents from the external environment.
It regulates the exchange of essential substances between the cells contents and the external environment
It communicates with other cells.
Why is the cell membrane described as a "fluid mosaic"?
When view from above, the membrane looks something like a lumpy, constantly shifting mosaic of tiles. A double layer of phospholipids forms a viscous, fluid "grout" for the mosaic; assorted proteins are the "tiles" which can oveabout within the phospholipid layers. Thus, although the components within the plasma membrane remain relatively constant, the overall distribution of proteins and various types of phospholipids can change over time.
how do rates of diffusion vary with different states of matter, and with temperature, and why?
rates of diffusion vary with different states of matter due to a "concentration gradient"
What is diffusion?
The movement of particles from regions of higher concentration to regions of lower concentration.
What occurs in simple diffusion ?
Water, Dissolved gases and lipid-soluble molecules diffuse through the phospholipid bilayer.
What occurs in facilitated diffusion?
water soluble molecules cross the membrane through the protein channels or with the assistance of protein carriers.
What are the three major categories of membrane proteins?
Transport Proteins, Receptor Proteins and Recognition Proteins.
What is a transport protein?
Transport proteins regulate the movement of hydrophilic molecules through the plasma membrane.