Major Types Of Chemical Compounds In Plants & Animals

Living systems can be organized into the following levels or categories, starting with the simplest units and proceeding to the largest and most complex levels of organization:

Subatomic particles (electrons, protons and neutrons) form atoms (hydrogen, helium, oxygen, iron, etc.) which form molecules (water, glucose, cellulose, etc.) which form complex macromolecules (glycoproteins, DNA, RNA, etc.) which form subcellular units called organelles (nucleus, mitochondrion, chloroplast, etc.) which form cells which form tissues (muscle, nerve, adipose, epithelial, etc.) which form organs (brain, heart, liver, root, leaf, etc.) which form an individual organism. 

All of the elements are listed in a periodic table by their atomic number or number of protons. In a neutral atom the number of protons is equal to the number of electrons. For more click here.

Courtesy: W. P. Armstrong, http://waynesword.palomar.edu