what seperates inside of cell from extrenal enviroment
plasma membrane
proteins embbeded in membrane are
integral proteins
Many other proteins attached either to outside of membrane or inside of membrane are ....
Peripheral Proteins
proteins from what in membrane
mosaic pattern
Model of cell membrane = “Fluid-Mosaic Model” is what?
based on changing location and pattern of proteins in a fluid phospholipid bilayer
what are Glycolipids
are carbohydrates attached to phospholipids
what are carbohydrates attached to proteins
Glycoproteins
how many categories of proteins are there in membranes
there are Five
what are Carrier proteins?
proteins combines with molecules or ions and transports them across membrane
what are Cell recognition proteins
glycoproteins that help body defend itself against disease
what are Channel proteins
form a channel through membrane to allow specific molecule or ion to cross membrane
what are Enzymatic proteins
proteins that catalyze specific reaction in membrane
what are Receptor proteins
proteins in membrane that bind to specific substance and alter cell metabolism
Permeability of Cell Membranes
sec2
what regulates passage of molecules into and out of cell
membrane
what allows some molecules to pass but not others
Membrane is differentially permeable
Membrane is semi-permeable
it allows some molecules to pass but not others Those substances that cannot pass through membrane may be transported by carrier proteins or may cross through channel proteins
Molecules may cross membrane by Diffusion or Facilitated Transport
Energy NOT required
Macromolecules and other substances may cross membranes by
Active Transport, Exocytosis, Endocytosis – Energy IS required
Diffusion
movement of molecules from place of higher concentration to place of lower concentration
gas exchange of oxygen into lungs is example of
diffusion
what is solution?
homogeneous mixture of two or more substances; often consists of liquid solvent in which solute is dissolved; solute will NOT settle out of solvent
what is Osmosis
it is the diffusion of water across semi-permeable membrane because of concentration differences (concentration of solute is higher on one side of membrane than on other side
Isotonic solution
solution concentration is the same on both sides of membrane; therefore, no net movement of water across membrane; cell volume remains the same
what is Hypertonic solution
solution concentration outside cell is higher than inside concentration; cell shrinks by losing water
what is Hypotonic solution
solution concentration outside cell is lower than inside cell; cell swells because of water uptake; cell may undergo cytolysis
Cytolysis
bursting of cell due to uptake of water
Transport by Carrier Proteins
Some proteins in membranes transport molecules across membranes
Facilitated transport
no energy required; moves molecules from higher to lower concentration
Active transport
energy is required; moves molecules from lower concentration to higher concentration; uses carrier molecules in membranes
Vesicle Formation
Exocytosis
process by which intracellular vesicle fuses with membrane so that contents of vesicle released outside cell
Endocytosis
process by which substances moved into cells by phagocytosis or pinocytosis or receptor-mediated endocytosis