Cellular Transport & Homeostasis

Cellular Transport

The movement of substances across the cell membrane to maintain homeostasis

Passive Transport

Movement of substances across the membrane without using cellular energy

Molecular Motion

Constant random movement of molecules in all directions

Diffusion

Movement of molecules from an area of high concentration to low concentration

Concentration Gradient

Difference in concentration of a substance across a space or membrane

Net Movement

Overall movement from higher concentration to lower concentration

Diffusion Across a Membrane

Movement of small nonpolar molecules like oxygen and carbon dioxide through the membrane

Dynamic Equilibrium

Even distribution of molecules while movement continues

Facilitated Diffusion

Diffusion across a membrane with the help of channel proteins

Channel Proteins

Proteins that allow specific substances to pass through the membrane

Osmosis

Diffusion of water across a selectively permeable membrane

Aquaporins

Protein channels that transport water across the cell membrane

Solvent

The substance that does the dissolving, usually water

Solute

The substance that is dissolved in a solvent

Tonicity

The amount of dissolved substances in a solution

Hypotonic Solution

A solution with a lower solute concentration than the cell

Hypertonic Solution

A solution with a higher solute concentration than the cell

Isotonic Solution

A solution with equal solute concentration inside and outside the cell

Osmotic Pressure

The force caused by the movement of water into or out of a cell

Active Transport

Movement of substances against the concentration gradient using energy

ATP

A molecule that provides energy for active transport

Protein Pumps

Transport proteins that move substances using energy

Bulk Transport

Movement of large molecules or groups of molecules using vesicles

Vesicles

Membrane-bound sacs used to transport materials in cells

Endocytosis

Process by which cells take material into the cell

Exocytosis

Process by which cells release material out of the cell

Homeostasis

Maintenance of stable internal conditions in cells and organisms

Stimulus

A change in the environment that causes a response

Cell Specialization

Process where cells develop specific structures and functions

Prokaryotes

Simple cells without membrane-bound organelles

Eukaryotes

Cells with membrane-bound organelles and internal organization

Levels of Organization

Order of biological organization from cells to organisms

Cell Signaling

Process by which cells communicate with each other

Chemical Signals

Signals that use molecules to transmit information between cells

Electrical Signals

Signals that use electrical impulses to transmit information

Receptors

Proteins on the cell membrane that receive signals