Adapted from Practicing Biology
1. Help students identify the major differences among the four main types of biological macromolecules: carbohydrates, lipids, proteins, and nucleic acids.
2. Use their understanding from the goals above to predict how various structural modifications can affect the behavior of macromolecules.
Part A. Answer the questions. Then use your answers to develop simple rules for identifying carbohydrates, lipids, proteins, and nucleic acids.
1. What is the approximate C:H:O ratio in each of the following types of macromolecules?
There is no reliable C:H:O ratio for proteins.
2. Which of the compounds listed in question 1 can often be composed of C, H, and O alone?
Carbohydrates and lipids can often be composed of C, H, and O alone.
3. Which of the compounds can be identified by looking at the C:H:O ratios alone?
Only carbohydrates and some lipids can be identified using C:H:O ratios alone.
4. What other elements are commonly associated with each of these four types of macromolecules?
Always contain P
No (except for phospholipids)
Always contain N
Frequently contain S
5. Based on your answers to questions 1–4, what simple rule(s) can you use to identify the following macromolecules? carbohydrates Look for a 1:2:1 C:H:O ratio. Many carbohydrates will contain no P, N, or S.