Molecules of Life. Chapter 2 Part 2. 2.6 Organic Molecules. The molecules of life – carbohydrates, proteins, lipids, and nucleic acids – are organic molecules Organic Type of molecule that consists primarily of carbon and hydrogen atoms. Some Elemental Abundances.
cis double bond
trans double bond
long carbon chain
A stearic acid
B linolenic acid
C oleic acid
D elaidic acid
Fig. 2-14, p. 32
one layer of lipids
B a lipid bilayer
Fig. 2-15b, p. 32
1. Primary structure (polypeptide formation)
2. Secondary structure
3. Tertiary structure
4. Quaternary structure
5. Fibrous proteins may aggregate into a larger structure, such as keratin filaments
1) A protein’s primary structure consists of a linear sequence of amino acids (a polypeptide chain).
2) Secondary structure arises when a polypeptide chain twists into a coil (helix) or sheet held in place by hydrogen bonds between different parts of the molecule. The same patterns of secondary structure occur in many different proteins.
3) Tertiary structure occurs when a chain’s coils and sheets fold up into a functional domain such as a barrel or pocket. In this example, the coils of a globin chain form a pocket.
4) Some proteins have quaternary structure, in which two or more polypeptide chains associate as one molecule. Hemoglobin, shown here, consists
of four globin chains (green and blue). Each globin pocket now holds a heme group (red).
5) Many proteins aggregate by the thousands into larger structures, such as the keratin filaments that make up hair.
Fig. 2-18, p. 35