exchange of substances Flashcards
what is the role of a membrane
- controls what goes in and out of the cell
- keeps all cellular components inside
- allows the cell to change shape
what components make up a plasma membrane
main structure = phospholipid bilayer
glycoproteins
transport proteins
glycolipid
cholesterol
why is a plasma membrane also referred to as a fluid mosaic model
lipids and proteins can move
proteins scattered throughout membrane
what is the role of a glycoprotein in a cell membrane
act as recognition site/antigen
helps with attachment of cells
what is the role of a phospholipid in a cell membrane
- allows soluble substances to move in and out of the cell
- prevents water leaving/entering the cell
what is the role of proteins in a cell membrane
provides structural support
allows active transport across membranes
role of glycolipids in a cell membrane
acts as recognition sites
helps with adhesion
role of cholesterol in cell membranes
makes membrane less fluid
prevents leakage of water
how does a phospholipid bilayer act as a barrier
hydrophillic head, stops most soluble and polar molecules into the cell
examples of passive transport
osmosis
diffusion
definition of diffusion
random net movement of particles from an area of high to low concentration
what type of particles can be diffused by simple diffusion
small and nonpolar molecules
definition of facilitated diffusion
net movement of particles from a high to low concentration with a carrier protein
