3 Chapter 3: Chemistry of Life
Chapter 3 Outline
3.1 The Building Blocks of Molecules
- 3.1.1 Atoms
- 3.1.2 Chemical Bonds
3.2 Water
- 3.2.1 Water is Polar
- 3.2.2 Water Stabilizes Temperature
- 3.2.3 Water is an Excellent Solvent
- 3.2.4 Water is Cohesive
- 3.2.5 Buffers, pH, Acids, and Bases
3.3 Biomolecules
- 3.3.1 Carbon
- 3.3.2 Carbon Bonding
- 3.3.3 Carbohydrates
- 3.3.4 Lipids
- 3.3.5 Proteins
- 3.3.6 Nucleic Acids
The elements carbon, hydrogen, nitrogen, oxygen, sulfur, and phosphorus are the key building blocks of the chemicals found in living things. They form the carbohydrates, nucleic acids, proteins, and lipids (all of which will be defined later in this chapter) that are the fundamental molecular components of all organisms. In this chapter, we will discuss these important building blocks and learn how the unique properties of the atoms of different elements affect their interactions with other atoms to form the molecules of life.
Food provides an organism with nutrients—the matter it needs to survive. Many of these critical nutrients come in the form of biomolecules (also called biological macromolecules), or large molecules necessary for life. These macromolecules are built from different combinations of smaller organic molecules. What specific types of biological macromolecules do living things require? How are these molecules formed? What functions do they serve? In this chapter, we will explore these questions.
Learning Objectives
You will understand
- basic chemistry by distinguishing between elements, atoms, ions and molecules.
- water’s role in life by recognizing that the abundance and polar properties of water make it critical to biology, describing its critical role as a solvent for biological molecules
- some essentials of organic chemistry by listing the four biomolecules (proteins, carbohydrates, nucleic acids, and lipids), identifying the building blocks of the first three, and explaining the function of all four.
3.1 The Building Blocks of Molecules
At its most fundamental level, life is made up of matter. Matter occupies space and has mass. All matter is composed of elements, substances that cannot be broken down or transformed chemically into other substances. Each element is made of atoms, each with a constant number of protons and unique properties. A total of 118 elements have been defined; however, only 92 occur naturally, and fewer than 30 are found in living cells. The remaining 26 elements are unstable and, therefore, do not exist for very long or are theoretical and have yet to be detected.
Each element is designated by its chemical symbol (such as H, N, O, C, and Na), and possesses unique properties. These unique properties allow elements to combine and to bond with each other in specific ways.
3.1.1 Atoms
An atom is the smallest component of an element that retains all of the chemical properties of that element. For example, one hydrogen atom has all of the properties of the element hydrogen, such as it e