Unit 2: Basic Chemistry
Nature is not based on one field of study. It incorporates biology, physics, chemistry, and other academic disciplines. Life is multidisciplinary and is driven by chemical processes. Since so many biology topics overlap with basic principles of chemistry, you need a basic understanding and appreciation of chemistry to fully understand biology. For example, in Unit 1 we discussed that the atom is the first part of the biological hierarchy. In this unit, we provide an understanding of this foundational level of organization.
Completing this unit should take you approximately 5 hours.
2.1: Atoms and Molecules
Atoms and elements are the smallest structures in the universe. These substances cannot be broken down any further. Elements come together to form molecules which are the building blocks of the lowest level of life, the cell. To understand biology, you need to understand these foundation elements that form the structures of life.
The primary subatomic particles are protons, neutrons, and electrons. Protons and neutrons make up the nucleus of an atom. Electrons are found outside the nucleus. A proton has an electrical charge of +1. A neutron is nearly identical in size to a proton, but it has no charge. An electron is much smaller than a proton or neutron. An electron is also a charged particle. Despite being much smaller than a proton, the charge of an electron is equal in magnitude to the charge of a proton. However, the charge is opposite, so each electron has a charge of -1.
Thermodynamics is the branch of science that studies how energy is transformed from one form to another. We study thermodynamics in biology because organisms are involved in many energy transactions. In other words, organisms are thermodynamic systems. Biochemical reactions must follow the laws of thermodynamics to predict whether reactions will occur spontaneously, or without any energy required.
For example, living things need the ability to move. Energy gives this power, but it must be harnessed and transformed from one form of energy to another. Living things need usable forms of energy.
Two of the four laws of thermodynamics are especially important in biology:
- The first law of thermodynamics states that energy cannot be created or destroyed, although it can be transferred and transformed. This is also known as the law of conservation of energy.
- The second law of thermodynamics states that every energy transaction increases the entropy (disorder) of the universe. This second law implies that every energy transaction involved some loss of usable energy as heat, so no energetic process (including those occurring in organisms) can ever be perfectly efficient.
We will review thermodynamics again in Unit 5 when we study metabolism and metabolic pathways.
Unit 2 Assessment