Evolution of Protein Families
According to current dogma, protein families arise in two ways. Firstly, the separation of a parent species into two genetically isolated descendent species allows a gene/protein to independently accumulate variations (mutations) in these two lineages. This results in a family of orthologous proteins, usually with conserved sequence motifs. Secondly, a gene duplication may create a second copy of a gene (termed a paralog). Because the original gene is still able to perform its function, the duplicated gene is free to diverge and may acquire new functions (by random mutation). Certain gene/protein families, especially in eukaryotes, undergo extreme expansions and contractions in the course of evolution, sometimes in concert with whole genome duplications. This expansion and contraction of protein families is one of the salient features of genome evolution, but its importance and ramifications are currently unclear.
Read more about this topic: Protein Families
Famous quotes containing the words evolution of, evolution, protein and/or families:
“The evolution of a highly destined society must be moral; it must run in the grooves of the celestial wheels.”
—Ralph Waldo Emerson (1803–1882)
“The more specific idea of evolution now reached is—a change from an indefinite, incoherent homogeneity to a definite, coherent heterogeneity, accompanying the dissipation of motion and integration of matter.”
—Herbert Spencer (1820–1903)
“Firm-style bean curd insoles cushion feet, absorb perspiration and provide more protein than meat or fish innersoles of twice the weight. Tofu compresses with use, becoming more pungent and flavorful. May be removed when not in use to dry or marinate. Innersoles are ready to eat after 1,200 miles of wear. Each pair provides adult protein requirement for 2 meals. Insoles are sized large to allow for snacks. Recipe booklet included.”
—Alfred Gingold, U.S. humorist. Items From Our Catalogue, “Tofu Innersoles,” Avon Books (1982)
“Women have entered the work force . . . partly to express their feelings of self-worth . . . partly because today many families would not survive without two incomes, partly because they are not at all sure their marriages will last. The day of the husband as permanent meal-ticket is over, a fact most women recognize, however they feel about “women’s liberation.””
—Robert Neelly Bellah (20th century)