Cell Membrane Lecture Notes

Flashcards for lecture notes on cell membrane structure and function, gradients, and permeability.

Cell Membrane

A thin, flexible, and sturdy barrier that surrounds the cytoplasm of a cell.

Fluid Mosaic Model

Describes membrane structure as a sea of lipids in which proteins float like icebergs.

Lipid Bilayer

Two back-to-back layers of phospholipid, cholesterol, and glycolipid molecules.

Phospholipids

Lipids that make up 75% of the cell membrane.

Amphipathic

Having both polar and nonpolar regions within the same molecule.

Integral Proteins

Extend into or completely across the cell membrane.

Peripheral Proteins

Attached to either inner or outer surface of cell membrane and are easily removed from it.

Selective Permeability

Allows some substances to cross but excludes others.

Diffusion

Random mixing of particles in a solution as a result of the particle’s kinetic energy.

Concentration Gradient

Molecules will diffuse down their concentration gradients

Electrical Gradient

Ions will be influenced by membrane potential in addition to their concentration gradient.

Electrochemical Gradient

Movement of ions will be influenced by both the concentration gradient and electrical gradient.

Osmosis

Diffusion of H2O across membranes

Osmosis

Net movement of water through a selectively permeable membrane from an area of high water concentration to an area of lower water concentration.

Pd

Water movement through lipid bilayer

Pf

Water movement through water channel

Osmotic Pressure

The pressure applied to a solution to prevent the inward flow of water across a semi-permeable membrane