• Unit 3: Biological Molecules

    All organisms contain the organic biological molecules – carbohydrates, proteins, lipids, and nucleic acid – that are essential to life. Having an understanding of the structures and functions of these molecules will help you understand what organic molecules our body needs to function properly.

    Completing this unit should take you approximately 5 hours.

    • Upon successful completion of this unit, you will be able to:

      • list the characteristics of water that make it important to life as we know it;
      • explain the characteristics that are necessary to make something alive;
      • recognize the structure of the four major biological macromolecules;
      • describe the functions of the four major biological macromolecules;
      • indicate the monomers and polymers of carbohydrates, proteins, and nucleic acids; and
      • describe the four levels of protein structure.

    • 3.1: Water and Organic Molecules

      • Water URL

        Water is one of the most important compounds on Earth, since no living organisms can survive without water. Understanding the unique properties of water is very important for the study of biology. Read this section, and be sure to complete the multiple choice and free response questions at the end of the section.

    • 3.2: Acids and Bases

      • pH, pOH, and pKw Page

        The hydrogen ion concentration of biological systems can be measured using the pH scale. Watch this lecture to learn about the pH scale and how it affects biological systems.

      • Electrolytes and pH URL

        Read this section and complete the "Did I Get This" activity at the end of the section. How can the pH measurements of acidic and basic solutions affect living organisms?

      • Acids and Bases Page

        Watch this lecture to learn about acids and bases, and how they relate to the concentration of hydrogen ions in a solution.

    • 3.3: Biological Macromolecules

      • Biological Macromolecules Page

        Watch this lecture to review biological macromolecules and their role in biological organisms.

      • More on Biological Macromolecules URL

        Biological macromolecules are the raw ingredients that allow living cells to exist and survive. Read the introduction, and then click "next" to also read sections 3.1 to 3.5, "Synthesis of Biological Macromolecules", "Carbohydrates", "Lipids", "Proteins", and "Nucleic Acids". Make sure to also complete the multiple choice and free response questions at the end of each section

    • Unit 3 Assessment

      • Unit 3 Assessment Quiz

        Take this assessment to see how well you understood this unit.

        • This assessment does not count towards your grade. It is just for practice!
        • You will see the correct answers when you submit your answers. Use this to help you study for the final exam!
        • You can take this assessment as many times as you want, whenever you want.