cell membrane + cell transport

Phospholipid

A macromolecule with a phosphate head and two fatty acid tails.

Hydrophilic heads

Portion of the phospholipid molecule that is attracted to water (polar.)

Hydrophobic tails

Portion of the phospholipid molecule that is repelled by water (nonpolar.)

Phospholipid bilayer

Two layers of phospholipids tail to tail; semo-permeable. 

Marker protein

Protein with an attached carbohydrate chain, cell identification.

Channel proteins

Proteins embedded in the phospholipid bilayer used for facilitated diffusion.

Cholesterol

A molecule in the phospholipid bilayer helps cell membranes maintain flexibility. 

Plasma membrane

A selectively-permeable phospholipid bilayer forming the boundary of the cells.

Active transport

The movement of materials from low concentration to high concentration using energy.

Endocytosis

Moving materials into the cell using energy.

Phagocytosis

Moving solid materials into the cell using energy.

Pinocytosis

Moving liquid materials into the cell using energy.

Exocytosis

Moving materials out of the cell using energy.

Diffusion

The process by which molecules move from an area of higher solute concentration to an area of lower solute concentration. 

Hypertonic solution

Concentrated solution.

Hypotonic solution

Dilute solution or low concentration solution.

If a cell is in a hypertonic solution

Water moves out of a cell, so then the cells gets smaller and shrinks.

If a cell is in a hypotonic solution

Water moves into a cell, so it gets bigger and swells. 

Passive transport

Requires NO energy, movement of molecules from high to low concentration, moves with the concentration gradient.

Active transport

Energy-requiring process that moves material across a cell membrane against a concentration gradient.

Permeable membrane

A membrane that allows substances (especially liquids) to pass or diffuse through. 

Semipermeable membrane

Characteristic of a cell membrane which allows some molecules to pass through but not others.

Solute

A substance that is dissolved in a solution.

Solvent

The liquid that is doing the dissolving (usually a liquid, but can sometimes be a solid of gas.)

Solution

A mixture of solute and solvent.