General ---------Biology ------------------Online------------------   ----wilcox@sunline.net Ch.  2 :  The Chemical Context of Life

Much of this course will deal with how cells store and consume energy, as all the processes of life, such as reproduction, growth, movement, maintenance, all require energy.

A simplified covalent bond is drawn below.
 

Both images below represent a covalent bond.

How many covalent bonds does glucose contain?  ______.  (answer)
When you burn glucose, cellulose or any organic molecule, the energy in the bonds is released as heat and light. 

If the bonds are broken, what happens to the C, H and O atoms in the organic molecule?

You may have noticed there were more oxygen atoms in the resulting carbon dioxide and water molecules than were present in the glucose.  If this glucose was broken down by enzymes in your body, where did these additional oxygen atoms most likely come from?  __________________________ 

When you breath in, you breath in ________;  when you exhale, you exhale __________.

• covalent bonds store energy
• these bonds are the source of energy in carbohydrates such as glucose
• when covalent bonds break, they release this stored energy
• oxygen must be present for enzymes (or heat) to "burn" organic molecules
• the CHO atoms from the burned organic molecule, reform as C₂O and H₂O