Organic compounds - Proteins

Proteins are:

• 50% of most cell dry weight.
• Most structurally complex - unique 3D shape.
• Polymers composed of amino acids.

Amino Acids

• Monomer of an α carbon with 4 covalent bonds. Bond partners:
  • carboxyl     -COOH
  • hydrogen     -H
  • amino    -NH₂
  • R group (side chain or side group).
• The 20 common amino acids differ by the R group.
• Simple R group : H (glycine)
• Complex R group : carbon skeleton with various functional groups (Phenylalanine).

Peptide Bonds

• A peptide is a small protein.
• Peptide bond - carboxyl and amino groups join
  through dehydration synthesis.
• Many peptide bonds forms a polypeptide.
• Forms a -N-C-C-N-C-C-N- backbone.

Conformation

• Polypeptide chains wind, fold and twist on themselves.
• Structure (shape) determined by amino acid sequence.
• Structure determines function in cell. Structures form from:
  • hydrogen bonds.
  • ionic bonds.
  • disulfide bridge (covalent).
  • hydrophobic interactions.
• Sequence Structure Function !!
• Denaturation - when environmental conditions
  cause protein to change its shape.

Functions of Proteins

• Structural support - keratin.
• Storage - ovalbumin.
• Transportation - hemoglobin.
• Movement - actin & myosin.
• Defense - antibodies.
• Signaling (hormones) - insulin.

Collection of images for proteins.