In biology, transport is the process by which molecules, ions or substrates are moved across biological membranes such as the plasma membrane. This can be passive or active, simple or facilitated and intracellular or extracellular. Passive transport requires no energy, while active transport uses the cell’s ATP-stored energy to move substances against a concentration gradient. The term is derived from the Latin words trans-, meaning “across,” and porto, meaning to carry.
In general, the movement of molecules from an area of high to an area of low concentration is called diffusion. For example, odors diffuse through air, salt diffuses through water and nutrients diffuse from blood into body tissues. This movement is a random process and can occur in gases, liquids or solids. When a substance is mixed with another, for example, water and sugar, this is called a solution. The dissolved substance is called the solute and the larger quantity of solute in a given volume, the higher the concentration.
Biological materials that are used for purposes of diagnosis, research or treatment of disease must be shipped in accordance with the TDG Regulations. This includes infectious substances (Category B and patient specimens), biological products, genetically modified organisms, and medical/clinical waste.
Biological material must be packaged in an outer container that is a sturdy and durable container that can withstand physical damage while in transit, and a secondary package that has an itemized list of the contents and is securely sealed. BU EHS will coordinate the transportation of these materials in compliance with TDG regulations and all applicable laws.