Biology - Chapter 3A: Introduction to the Plasma Membrane

plasma membrane

a selectively-permeable phospholipid bilayer and embedded proteins separating the intracellular and extracellular environment

intracellular

inside a cell

extracellular

outside a cell

selective permeability

property of a plasma membrane that ensures only specific substances cross

fluid mosaic model

model that describes the arrangement and movement of the molecules that make up a cell membrane

phospholipid

a molecule with a hydrophilic phosphate head and two hydrophobic fatty acid tails.

phospholipid bilayer

a two-layered arrangement of phosphate and lipid molecules that form a plasma membrane

hydrophilic

"water-loving" polar molecules

hydrophobic

"water-fearing" non-polar molecules

amphiphilic/amphipathic

a molecule that has both hydrophilic and hydrophobic parts

polar molecule

molecules with both positive and negative parts (hydrophilic)

non-polar molecule

molecules with a an even distribution of charge, no clear positive and negative end (hydrophobic)

protein

3d macromolecules made of folded amino acid monomer chains

carbohydrate

compound made up of carbon, hydrogen, and oxygen atoms; a major source of energy for living organisms (e.g., sugars, starches, and cellulose).

cholesterol

lipid responsible for the regulation of membrane fluidity of animal cell membranes

integral protein

membrane protein that is permanently attached/embedded to the plasma membrane.

transmembrane protein

integral membrane protein that spans the entire width of a cell membrane

peripheral protein

proteins only temporarily attached to the plasma membrane - forms temporary bonds, receives signals - communication. can be attached to the cytoskeleton

glycolipid

/phospholipid with covalently attached carbohydrates. responsible for cell signalling, identification recognition, and adhesion

glycoprotein

a protein with covalently attached carbohydrates. responsible for cell signalling, recognition and adhesion

molecule

two or more atoms held together by covalent bonds

compound

a substance made up of atoms with two or more different elements