Chapter 3: Introductory Chemistry for Biology
Learning Objectives
Course Outcomes for this chapter:
- Describe the fundamental composition of matter.
- Identify the three subatomic particles.
- Identify the four most abundant elements in the body.
- Explain the relationship between an atom’s number of electrons and its relative stability.
- Distinguish between ionic bonds, covalent bonds, and hydrogen bonds.
Living things are highly organized and structured, following a hierarchy that can be examined on a scale from small to large. The examination of the smallest parts involves a knowledge of chemistry. We can put the levels of organization of living things in order from smallest to largest.
- The atom is the smallest and most fundamental unit of matter. It consists of a nucleus surrounded by electrons.
- Atoms form molecules. A molecule is a chemical structure consisting of at least two atoms held together by one or more chemical bonds. Many molecules that are biologically important are macromolecules, large molecules that are typically formed by polymerization (a polymer is a large molecule that is made by combining smaller units called monomers, which are simpler than macromolecules).
These first 2 levels (or 3, depending on how you categorize macromolecules) are typically studied in chemistry or biochemistry courses. However, a working knowledge of atoms and molecules is required to understand how these small pieces work to make larger, living organisms.
- Some cells contain aggregates of macromolecules surrounded by membranes; these are called organelles. Organelles are small structures that exist within cells.
- All living things are made of cells; the cell itself is the smallest fundamental unit of structure and function in living organisms.
- In larger multicellular organisms, cells combine to make tissues, which are groups of similar cells carrying out similar or related functions.
- Organs are collections of tissues grouped together performing a common function. An organ system is a higher level of organization that consists of functionally related organs.
- Mammals have many organ systems. For instance, the circulatory system transports blood through the body and to and from the lungs; it includes organs such as the heart and blood vessels.
- Organisms are individual living entities. For example, each tree in a forest is an organism. Single-celled prokaryotes and single-celled eukaryotes are also considered organisms and are typically referred to as microorganisms.
License and attributions:
- Anatomy and Physiology, Second edition, 2022, Betts, J.G. et al. License: CC BY 4.0. Located at https://openstax.org/books/anatomy-and-physiology-2e/pages/2-introduction
