Inside "Biological Building Blocks":

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CancerQuest > Introduction to Cancer Biology > An Introduction to the Biological Building Blocks > Section Summary: The Building Blocks

Section Summary: The Building Blocks

All living things, including the cells that make up a human body are comprised of a small subset of different biomolecules. There are four main classes, as described below:

1. Carbohydrates
   • Carbohydrates are comprised of carbon (C), hydrogen (H), and oxygen (O) molecules.
   • Sugars are common carbohydrates.
   • Carbohydrates serve several functions inside cells:
     • Major energy source
     • Provide structure
     • Communication
     • Cell adhesion
     • Defense against and removal of foreign material
2. Proteins
   • Proteins are comprised of amino acids.
   • Proteins serve several functions inside living things:
     • Structure of hair, muscle, nails, cell components, and cell membranes
     • Cell transport
     • Biological catalysts or enzymes
     • Maintaining cell contact
     • Control cell activity
     • Signaling via hormones
3. Lipids
   • A wide variety of biomolecules including fats, oils, waxes and steroid hormones.
   • Lipids do not dissolve in water (they are hydrophobic) and are primarily comprised of carbon (C), hydrogen (H), and oxygen (O).
   • Lipids serve several functions in living things:
     • Form biological membranes
     • Fats may be stored as a source of energy
     • Oils and waxes provide protection by coating areas that could be invaded by microbes (i.e. skin or ears)
     • Steroid hormones regulate cell activity by altering gene expression
4. Nucleic Acids
   • All of the information needed to control and build cells is stored in these molecules.
   • Nucleic acids are comprised of nucleotides which are abbreviated A, C, G, T, and U.
   • There are two main types of nucleic acid, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA):
     • DNA
       • DNA has a double helix structure comprised of nucleotides A, C, G, and T.
       • DNA is located in the nucleus of the cell.
       • DNA is the storage form of genetic information.
     • RNA
       • RNA is typically single stranded and comprised of nucleotides A, G, C, and U.
       • RNA is copied from DNA and is the working form of the information.
       • RNA is made in the nucleus and mRNA is exported to the cytosol.

Additional biomolecules can be made by combining these four types. As an example, many proteins are modified by the addition of carbohydrate chains. The end product is called a glycoprotein.