Classes of Biomolecules

From Chemistry Teachers United

Classes of Biomolecules

The following is a list of functional groups commonly found in biological molecules. Rotate through the group describing what is in the table, with each member describing just one functional group at a time.

[Table 1-1]

Questions

1. What is the difference between an amine and an imine?

2. Which functional groups are derivatives of carboxylic acids?

3. Give a specific example of a phosphoric acid ester (R is a general example).

4. What charge does your example have under physiological conditions?

Examples of amino acids [Amino acids—asparagine, cysteine, alanine (also stick figure & space-filling), from p. 7] Questions

5. Which functional groups are present in the examples of amino acids?

6. Make a line drawing of a general amino acids using R to represent the part that differs among amino acids.

7. Why are amino acids called amino acids?

8. The amino acids shown are actually alpha amino acids, where the α carbon is connected to the amine. Sketch a β amino acid.

9. Which one atom in α amino acids is chiral?

Check point (15 minutes to get here). Spy exchange.

10. Draw the amino acid in which the side chain, R, is the simplest thing possible. (This amino acid is called glycine.)

11. Is glycine chiral?

Examples of carbohydrates

[carbohydrates—glucose, both straight and as ring, ribose, and fructose]

12. Which functional groups are present in glucose?

13. What is the molecular formula of glucose?

14. What is the empirical formula of glucose?

15. What is the empirical formula of ribose?

16. How does fructose differ from glucose?

17. Carbon 1 refers to one of the carbon atoms in fructose. What is the rule for deciding which direction to start counting the carbon atoms from?

18. Which atoms in fructose are chiral?

19. Write a grammatically correct sentence stating the group’s definition of a carbohydrate.

Check point (14 minutes to get here). Spokespersons write definitions on board.
The ring structure of glucose is an example of an acetal. An acetal is formed from an aldehyde and an alcohol: [show mechanism]

20. In the ring form of glucose, indicate which carbon was originally an aldehyde, and which was an alcohol.

21. In the ring form of a carbohydrate, how can the carbonyl carbon (a carbon double-bonded to oxygen) be quickly identified?

Examples of nucleotides [nucleotides showing 5’-ATP (adenosine triphosphate) with nitrogenous base (adenine), ribose, and phosphate labeled]

22. In the nucleotide, the carbonyl carbon is carbon 1’, where the prime indicates the numbering refers to the sugar, rather than the nitrogenous base. Which carbon of the sugar is the phosphate attached to?

23. How would the structures of AMP and ADP (not shown) differ from the structure of ATP that is shown?

Examples of lipids [lipids—palmitate and cholesterol]

24. Which member of each of the following pairs of biomolecules would you expect to be more soluble in water?

a) cholesterol or alanine

b) palmitate or ATP

25. Based on the solubility of lipids in water, write a grammatically correct sentence stating the group’s definition of a lipid.

Check point (10 minutes to get here). Spokespersons present answer to last question.

26. List three ideas that the group agrees were learned today.

27. Write a grammatically correct statement of the group’s consensus of how it might improve its performance.

Exercise

28. Which class of biomolecules do the following compounds belong to?

[Add examples from end of chapter]
Problem

29. The nucleotide is drawn with the nitrogenous base folded over the sugar, because drawing it that way takes less space. However, this is not realistic, due to steric crowding (the nitrogenous base atoms and the ribose atoms bump into each other). Draw 3’-AMP with the nitrogenous base in a more realistic position (the number refers to the point of attachment of the phosphate).

Quiz (for next day)
To which class of biomolecules does each of the following four molecules belong? [Use examples from textbook]