Cell Respiration: Overview and ATP

Learning Objectives 

• Explain the importance of chemical energy for living organisms- the role of organic molecules and ATP

Why cell respiration is so important: 

Chemical Energy:

Cells/living organisms need energy for day to day work and therefore survival.  You couldn't contract your muscles (including the heart and the muscles that control inhalation), conduct nerve impulses, filter waste products from your blood or even do digestion without sufficient energy. There are many different kinds of energy, including light energy, sound energy, energy of movement (kinetic energy), but living organisms use chemical energy.

• • • • Chemical energy is the energy stored in chemical bonds due to the shared electrons.  When a cell breaks a chemical bond, it releases energy that the cell can use for work. 
      • All living organisms use chemical energy as their source of energy for day to day work in the cell. 

 ATP (AdenosineTriPhosphate)

All cells run on chemical energy, but they actually run on one specific type of chemical energy: the energy in the bonds of a molecule called AdenosineTriPhosphate, abbreviated as ATP.  We have already seen examples of this when we looked at active transport. The work of pushing molecules against their concentration gradient was done using the energy from ATP. 

The picture below shows the basic process: ATP has 3 phosphates attached one after the other by chemical bonds. The cell breaks one of these phosphate bonds. This releases energy for work and the cell is left with AdenosineDiPhosphate (ADP) and a loose phosphate.  

Cellular Respiration

Cells need a way to make a constant supply of ATP.  In order to do this, they need

• • • • • ADP + P=  the raw ingredients to make ATP 
        • Hydrogens and their electrons from chemical bonds in organic molecules = the source of energy to build the new ATP molecules from ADP and phosphate . 
        • Cell respiration enzymes and proteins= the machinery that will do the work of uniting the energy source with the ADP and P to make ATP 

Cell respiration is the process by which enzymes and proteins capture the energy from the chemical bonds of organic molecules (like glucose) and use it to build new ATP molecules.  To make this efficient, the cell does this in many small steps. This makes it challenging to learn, but that complexity is why it works so well. Don’t complain- congratulate your cells on being so darn efficient! We will need to strike a balance between enough details for you to understand the process, and not so much that you are overwhelmed.

Video Assignment 

This video goes over some of this same information. I have embedded questions in the video for you to answer. Some of the information will come from the above paragraphs and some from the video. 

Study Guide Questions