2.8 - A - Cell Respiration
Cell respiration is a function of life that all cells perform. It is the controlled release of energy in the form of ATP from organic compounds. It is carried out using enzymes in a careful and controlled way, so that as much as possible of energy released is in a usable form.
ATP is formed from ADP through the addition of a phosphate group. The energy necessary for this to happen is derived from breaking chemical bonds. ATP is cannot be transferred and is continuously needed, so cell respiration is an essential function in all cells.
Cells require energy for three main types of activities:
ATP provides energy or all of these processes. An advantage of this is that ATP is immediately available. This is accomplished by splitting ATP into ADP and phosphate (see left diagram). Afterwards, cell respiration can reattach the phosphate so that more energy is available.
**watch the 'ATP Cycle' below to see how this process works.
Aerobic respiration occurs when oxygen is available to a cell. This process allows for glucose to be more fully broken down which releases more energy (38 ATP) than when oxygen is absent (2 ATP).
Aerobically breaking down molecules involves a series of reactions in and out of the mitochondria. Glucose and oxygen are the inputs, while carbon dioxide, water and ATP are the products. Carbon dioxide is a waste product excreted by humans, but the water is useful and so retained.
Review Videos (WATCH!!)