Across the spectrum of living things on Earth, the same four macromolecules are found: proteins, carbohydrates, lipids, and nucleic acids. Each of these macromolecules plays an important role in the well-being of an organism. Biochemistry is the study of the chemical processes in living organisms, including reactions that involve these macromolecules. Carbohydrates provide energy and structure. Proteins catalyze chemical reactions that are vital to sustaining life. Lipids form the basis of cell membranes and nutrient molecules, as well as fats. DNA and RNA, the nucleic acids, contain and express the information necessary to create proteins required to carry out an organism's life processes.
At A Glance
- Proteins are formed from a sequence of amino acids linked by peptide bonds.
- Proteins can have four levels of structure, called primary, secondary, tertiary, and quaternary structure, and the function of a protein depends on its structure.
Enzymes are proteins that catalyze reactions in biological systems, and the structure of an enzyme is specific to the shape of the substrate molecule on which it acts.
Carbohydrates play two important roles in biological systems by providing energy and structure to living things.
- Lipids are insoluble in water and can be divided into three categories: triglycerides, phospholipids, and steroids.
Nucleic acids are responsible for DNA replication and protein synthesis, and they are made of nitrogenous bases, sugar, and phosphate.