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Biological Molecules. Protein Structure. First Five. Compare and Contrast: Triglyceride & Phospholipid. Proteins are Important. Proteins can serve many functions because they are diverse in size, shape, and chemical properties. Rhodopsin. Collagen. Protein Structure.
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Biological Molecules Protein Structure
First Five Compare and Contrast: Triglyceride & Phospholipid
Proteins are Important Proteins can serve many functions because they are diverse in size, shape, and chemical properties Rhodopsin Collagen
Protein Structure • No matter how large or complex a protein may be, its underlying structure can be broken down into just 4 basic levels of organization
1 Primary Structure The number and order/sequence of amino acids in the polypeptide chain The chains can be just a few amino acids long, or they can consist of chains of a thousand of amino acids or more.
2 Secondary Structure Refers to the regular folding regions of the polypeptide chain Most common types of secondary structures: • α-helix (spiral) • β-pleated sheet (folds) Secondary structural elements are stabilized by extensive hydrogen bonding
2 Secondary Structure: α-helix A cylindrical, rod-like helical arrangement of the amino acids Maintained by hydrogen bonds parallel to the helix axis
2 Secondary Structure: β-pleated sheet Hydrogen bonds form between adjacent sections of polypeptides that are either running in the same (parallel) or opposite (anti-parallel) direction
3 Tertiary Structure Refers to the 3-D arrangement of all amino acids in the polypeptide chain Aresult of ionic, hydrogen, or covalent bonds between the "-R" groups of the amino acids. As a result, alpha helical segments, beta pleated sheets, and random coils fold upon themselves. Folding and placement in a cell will also be influenced by the polarity of the amino acids.
3 Tertiary Structure
4 Quaternary Structure Refers to the association of two or more polypeptide chains or subunits into a larger piece For example, the hemoglobin molecule consists of two alpha subunits and two beta subunits; each of these four polypeptide chains has a binding site for oxygen.
4 Quaternary Structure
Guided Reading Follow along on the handout (from Tuesday) Answer guided questionscovering the concept of proteins.