Question

Using your knowledge of the main types of non-covalent interactions that occur in biological chemistry, discuss the spontaneous assembly of the four main types of biological structure with stable structures: DNA, proteins, glycans (such as cellulose and chitin) and cell membranes. Compare and contrast the various structures in terms of the forces and chemical structures driving their assembly. Finally, discuss why their particular molecular structures allow them to perform their biological roles.

Answer 1

Covalent bonds occurs within each linear strand and strongly bond the bases, sugars, and phosphate groups ( both within each component and between components). Hydrogen bonds occur between the two strands and involve a base from one strand with a base from the second in complementary pairing. When nucleotides are incorporated into DNA, adjacent nucleotides, are linked by a phosphodieter bond. A covalent bond is formed between the 5' phosphate group of one nucleotide and 3'- OH group of another. In this manner, each strand of DNA has a backbone of phosphate-sugar-phosphate.

The primary structure of protein consists of amino acids chained to each other. A peptide bond is type of covalent bond between the carboxyl group of one amino acid and the amino group of another amino acids themselves are made of atoms joined together by covalent bonds. Covalent bonds arise when two atoms share electrons.

Chitin is a modified polysaccharide that contains nitrogen. It is synthesized from units of N- acetyl-D- glucosamine. These units form covalent beta linkages. Chitin may be described as cellulose with one hydroxyl group in each monomer replaced with an acetyl amine group. This allows for increased hydrogen bonding between adjacent polymers, giving the chitin polymer matrix increased strength.

With non- covalent character inside the cell membrane, the hydrophobic molecules can easily pass through the cell membrane through passive diffusion. With this, the cell has control the molecules movements through the transmembrane protein complexes such as pores and gates.