BIOPHYSICS - LESSON 3

fluid mosaic model

S. J. Singer and Garth L. Nicolson

fluid mosaic model

mosaic of components including phospholipids, cholesterol, proteins, and carbohydrates

fluid mosaic model

5-10 nm thick and widely accepted model

glycoprotein

protein with carbohydrate attached

glycolipid

lipid with carbohydrate attached

phospholipids

main fabric of the membrane

Polar Heads

phosphate group and glycerol

Non-polar tails

2 fatty acid chain

cholesterol

regulates the fluidity of the membrane

cholesterol

changes based on the temperature of the cell's environment and antifreeze in the cell membrane

proteins

2nd major chemical component of plasma membranes

integral proteins

channels or pumps to move materials into or out of the cell

peripheral proteins

exterior or interior surfaces of membranes, attached either to integral proteins or to phospholipid molecules

carbohydrates

found on the exterior surface of cells and bound either to proteins or to lipids

carbohydrates

consist of 2-60 monosaccharide units and may be either straight or branched

passive transport

no energy required

diffusion

moving the substance from an area of high concentration to one of low concentration

faster

extent of the concentration which means that greater concentration difference, the rate of diffusion become _

slower

mass of the molecules diffusing which means that bigger molecules, the rate of diffusion become _

faster

temperature which means that higher temperature, the rate of diffusion become ___

slower

solving density which means that higher density, the rate of diffusion become _

facilitated transport

with the assistance of transmembrane proteins down a concentration gradient and from high to low concentration

osmosis

diffusion of water through a semipermeable membrane according to the concentration gradient of water across the membrane

osmolarity

describes the amount of solute in a solution measure of tonicity

active transport

requires energy

active transport

if a substance must move into the cell against its concentration gradient

phagocytosis

the cell membrane surrounds the particle and pinches off to form an intracellular vacuole

pinocytosis

the cell membrane surrounds a small volume of fluid and pinches off, forming a vesicle

receptor mediated endocytosis

uptake of substances by the cell is targeted to a single type of substance that binds at the receptor on the external cell membrane

exocytosis

opposite of the endocytosis, that its purpose is to expel material from the cell into the extracellular fluid