Proteins

3. Proteins: we are proteins "Building blocks of life" (Polypeptide, not all polypeptides are proteins)
      a. Functions:
           i. Structure- Bone, Cartilage, Muscle, Hair, Nails, etc.
          ii. Carriers- Insulin (Glucose), Hemoglobin (O2)
          iii. Defense- Antibodies, etc.
          iv. Movement- Muscle Fribers (actin & myosin)
          v. Regulators- Hormones, Neurotransmitters,

          vi. Cell Membrane Proteins- I'on Channels, Aquaproins (H2O), Pumps.
        ***  vii. Catalysts- Enzymes : lower the activation energy of reactions
     b. Structure: composed of long chains( > or =100) of Amino Acids.
            Amino Acid Stucture: Our cells put the amino acids together by using Dehydration Synthesis
                                Uses a *Peptide Bond

*All Organisms are built from the same 20 Amino Acids.*
In humans, 10 of the 20, are Essential( - must be obtained in diet), the other 10 are Non- Essential (can be made by the cells). In Plants all are Non-Essential. (some exceptions)

Four Levels of Protein Structure:
 1. Primary Structure: the chain of Amino Acids. NO proteins funtion at this level.

 2. Secondary Structure: the hydrogen bonding between R-Groups. Some proteins will function at this level. Ex. Alpha Helix : Hair                                         Ex. Beta Sheet: Silk