A closer look at cell membranes

Fluid mosaic model
every cell membrane has a cell composition or a mosaic of phospholipids, glycolipids, and proteins.

Adhesion Proteins
help cells of the same type locate each other and remain in the proper tissues.

Communication Proteins
form channels that match up across the plasma membranes of two cells.


Receptor Proteins
bind extracellular substance, such as hormones, that can trigger change in cell activities.

Recognition Proteins
are unique identity tags for each species.

Passive Transporter
A kind of transport by which ions or molecules move along a concentration gradient, which means movement from an area of higher concentration to an area of lower concentration.

Active Transporter
transport proteins pump a solute across the membarbe to the side where it is more concentrated.

Concentration gradient
is a difference in the number per unit volume of molecules of a substance between two adjoining regions.

Diffusion
is the name for the net movement of like molecules or ions down a concentration gradient.

Electric gradient
is simply a difference in electric charge between adjoining regions.

Pressure gradient
a difference in pressure exerted per unit volume between two adjoining regions.

Osmosis
is the diffusion of water across a selectively permeable mebrane, to a region  where the water concentration is lower.

Hypotonic solution
is the one with fewer solutes.

Isotonic solution
show no net osmotic movement.

Hydrostatic pressure
trugor pressure , against the wall or membrane that contains it.

Osmotic pressure
is one measure tendency of water to follow its water concentration gradient and move into that fluid.

Endocytosis
a small patch of plasma membrane balloons inward and pinches off inside the cytoplasm.

Exocytosis
a vesicle moves to the cell surface, and then the protein-studded lipid bilayer of its membrane fuses  with the plasma membrane.

Phagocytosis
is a common endocytic pathway.