The three main ideas of cell theory are that:
<span>
1. All living things are made up of one or more cells. </span>
<span>2. Cells are the basic units of life in which activities of life occur. </span>
<span>3. Living cells come only from other existing and living cells. </span>
<span>Food molecules like lipids, proteins and polysaccharides are broken down enzymatically via digestion process, which occurs in our intestine cells (digestive system). Those large polymeric molecules are broken down into their monomer subunits—proteins into amino acids, polysaccharides into sugars, and fats into fatty acids and glycerol. Formed small organic molecules are now ready for the oxidation (a process that produces ATP and consumes O2) which occurs partly in the cytosol and in the mitochondrion. Oxidation processes include glycolysis and citric acid cycle which are differently required in different tissues. Nervous system (nerve cells) rely almost entirely on a constant supply of <span>glucose<span> from the bloodstream. In contrast, liver cells supply glucose to actively contracting muscle system which needs a lot of ATP energy.</span></span></span>
Each cell contians 23 pairs of chromosomes
