the cellular level of organization

• plasma (cell) membrane • cytoplasm \ cytosol and organelles • nucleus \ chromosomes and genes

a flexible yet sturdy barrier that surrounds and contains the cytoplasm of the cell

• integral protein \ transmembrane • peripheral protein

help determine many of the functions of the cell membrane

membranes are fluid structures because most of the membrane lipids and many of the membrane proteins move easily in the bilayer membrane lipid and protein are mobile in their own half of the bilayer

serve to stabilize the membrane and reduce membrane fluidity

plasma membranes are selectively permeable the lipid bilayer is always permeable to small, nonpolar, uncharged molecules transmembrane proteins that act as channels or transporters increase the permeability of the membrane macromolecules are only able to pass through the plasma membrane by vesicular transport

is the difference in the concentration of a chemical between one side of the plasma membrane and the other

the difference in concentration of ions between one side of the plasma membrane and the other

these gradient make up an electrochemical gradient

simple diffusion facilitated diffusion osmosis

primary and secondary transport vesicular transport

the diffusion is influenced by the steepness of the concentration gradient temperature mass of diffusion substance surface area diffusion distance

transmembrane protein help solutes that are too polar or too highly charged move through the lipid bilayer the processes involved are channel-mediated facilitated diffusion carrier mediated facilitated

the net movement of a solvent through a selectively permeable membrane from an area of high concentration to an area of low concentration

tonicity of a solution relates to how the solution influences the shape of body cells

energy derived from ATP changes the shape of a transporter protein which pumps a substance across a plasma membrane against it concentration gradient

energy stored(in a hydrogen or sodium concentration gradient) is used to drive other substances against their own concentration gradient

membrane-enclosed secretory vesicles fuse with the plasma membrane and release their contents into the extracellular fluid

a combination of endocytosis and exocytosis used to move substances from one side of a cell, across it, and out the other side

• cytosol - also known as the intracellular fluid portion of the cytoplasm • organelles - they specialized structures that have specific shapes and perform specific functions

fluid mosaic bilayer studded with proteins; surrounds cytoplasm

protects cellular contents; makes contact with other cells; contains channels, transporters, receptors, enzymes, cell-identify markers, and linker proteins; mediates entry and exit of substance

cellular contents between plasma membranes and nucleus; cytosol and organelles