Proteins

• carbon, hydrogen, oxygen, nitrogen, and sulfur (CHONS)
• synthesized during transcription
• Amino acid


  building blocks of proteins
• Essential amino acid


  not produced by human body

  obtained from diet
• Nonessential amino acid


  synthesized by the human body

  not obtained by diet
• Primary structure 


  linear sequence of amino acids joined together by peptide bonds

  combined through a condensation reaction

  linked by peptide bonds
• Secondary structure

  local spatial arrangement of the polypeptide chain into regular structures, mainly alpha helices and beta sheets

  caused by the hydrogen bonding

  alpha - clockwise direction
• Tertiary structure

  overall three dimensional shape of a protein molecule determined by the interactions between amino acid side chains
• Quaternary Structure

  association of several protein chains or subunits into a closely packed arrangement
• Fibrous

  insoluble in water

  main components of the body

  collagen, keratin
• Globular

  soluble in water

  hemoglobin
• Denaturation


  protein interacts with agents such as heat, salt, baking soda, and rubbing alcohol

  disruption of the secondary and tertiary structure

  biologically inactive and less folded

  breaks peptide bond

  hydrogen bonds are disturbed
• pH changes


  intermolecular attractions
• increase in the temperature


  distrupt hydrogen bonds and nonpolar interactions
• addition of various chemicals

  destroys natural structure of protein