Question

Proteins can be classified based on structure or composition. List, describe, and provide an example of each subcategory within structural and composition.

a) Primary, Secondary, Tertiary; Fibrous, Globular; Collagen, Hemoglobin
b) Linear, Circular, Branched; Hydrophobic, Hydrophilic; Myoglobin, Actin
c) Alpha-helix, Beta-sheet, Random coil; Simple, Complex; Keratin, Elastin
d) Simple, Complex, Compound; Linear, Nonlinear; Insulin, Glucagon

Answer 1

Proteins can be categorized by structure (primary to quaternary) and composition (fibrous or globular). The primary structure is the amino acid sequence, the secondary includes α-helices and β-sheets, the tertiary is three-dimensional folding, and the quaternary involves multiple polypeptides. Collagen and hemoglobin are examples of fibrous and globular proteins, respectively.

Step-by-step explanation:

Proteins exhibit complex structures that can be categorized into several levels: primary, secondary, tertiary, and quaternary structures. The primary structure is the linear sequence of amino acids in a protein, which dictates the protein's ultimate shape and function. An example of this structure is insulin, a hormone crucial for glucose regulation.

Secondary structures, such as the α-helix and β-sheet, emerge from hydrogen bonding in the polypeptide backbone. Tertiary structure describes the overall three-dimensional structure of a single polypeptide chain, while quaternary structure is the arrangement of multiple such chains in a protein complex.

Proteins can also be classified based on their overall shapes and solubility; fibrous proteins like collagen are generally insoluble and have structural functions, whereas globular proteins like hemoglobin are soluble and often carry out metabolic functions.