A&P Seeley 3.1

The outer boundary of the cell through which the cell interacts with its external environment.

• Cell metabolism and energy use
• Synthesis of molecules
• Communication
• Reproduction and inheritance

Specialized cells responsible for transmitting genetic information.

Substances inside the cell

Substances outside the cell

The extracellular environment or to other cells.

The regulation of ion movement by cells results in a charge difference across the plasma membrane.

Positively charged

The collection of glycolipids, glycophoteins, and carbohydrates on the outer surface of the plasma membrane.

Molecules absorbed from the extracellular environment

A double layer of phospholipid molecules

Phospholipids and cholesterol

• The polar hydrophilic heads face inside and outside the cell.
• The nonpolar hydrophobic tails face each other in the interior of the plasma membrane.

It determines the fluid nature of the membrane and limits the movement of phospholipids, providing stability to the plasma membrane.

Lipids

Proteins

Penetrate deeply into the lipid bilayer, often extending from one surface to the other.

Are attached to the inner or outer surfaces of the lipid bilayer

Cell surface molecules that allow cells to identify one another or other molecules

Proteins with attached carbohydrates

Lipids with attached carbohydrates

Allow cells to attach to other cells or to extracellular molecules

Proteins that attach cells to other cells.

Proteins that attach cells to extracellular molecules

Integral proteins that allow ions or molecules to move from one side of the plasma membrane to the other.

Channel proteins, carrier proteins, and ATP-powered pumps

One or more integral proteins arranged so that they form a tiny channel through the plasma membrane.

Outward toward the hydrophobic part of the plasma membrane

Inward and line the channel

Channel proteins that are always open and are responsible for the permeability of the plasma membrane to ions when the plasma membrane is at rest.

Protein ion channels that can be opened or closed.

Small molecules that bind to the proteins or glycoproteins

Gated ion channels that open and close in response to chemical signals (ligands)

Gated ion channels that open or close when there is a change in charge across the plasma membrane.

Membrane proteins that move ions or molecules from one side of the plasma membrane to the other.