Organic compounds - Proteins
- 50% of most cell dry weight.
- Most structurally complex - unique 3D shape.
- Polymers composed of 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).
- A peptide is a small protein.
Peptide bond - carboxyl and amino groups jointhrough dehydration synthesis.
- Many peptide bonds forms a polypeptide.
- Forms a -N-C-C-N-C-C-N- backbone.
- 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 conditionscause protein to change its shape.
Functions of Proteins
- Metabolism - enzymes
- Structural support - keratin.
- Storage - ovalbumin.
- Transportation - hemoglobin.
- Movement - actin & myosin.
- Defense - antibodies.
- Signaling (hormones) - insulin.
Collection of images for proteins.