To understand life, you must understand the chemical logical the underlies it. Biochemistry Online starts with lipids, the simplest biomolecules from a physical and chemical structure, and builds from there, in a logical chemical progression to the structures, properties, and activities of the biomolecules of life.
- Lipids have distinct nonpolar and polar part and self-associate to form droplets, micelles and bilayers. Let’s understand this, then tackle complicated molecules like protein and carbohydrates.
- Proteins are polymers of the bifunctional monomer, amino acids. The twenty common naturally-occurring amino acids each contain an α-carbon, an α-amino group, an α-carboxylic acid group, and an α-side chain or side group. These side chains (or R groups) may be either nonpolar, polar and uncharged, or charged, depending on the pH and pKa of the ionizable group.
- To a first approximation, all the cells in an organism contain the same DNA (with the exception of germ cells and immune cells). Cell type is determined by what genes are expressed at a given time. Likewise, cells can change (differentiate) into different types of cells by altering the expression of genes. The central dogma of biology describes how genes are first transcribed to messenger RNA (mRNA), and then the mRNA is translated into a corresponding protein sequence.