Chemical Structure of Biologically Important Molecules
Name _________________________________________
Period_________
Introduction:
The structure of organic molecules is three-dimensional. Because this fact is not well represented
in textbooks, in this laboratory activity you will become acquainted with the three-dimensional
structure of some important molecules by constructing models.
Scientists often use molecular models to study how the functions of chemically and biologically
important molecules relate to molecular structure and to the overall shape and size of the
molecules. Advances in 3-D graphics have made the use of computer models much easier.
Nevertheless, physical models still remain useful for teaching and demonstrations.
Directions: READ THEM!!!!!
1. Obtain a molecular model kit. Work in a team.
2. Construct the models requested.
3. Use this key for your models.
(C) carbon
=
black
(N) nitrogen
= orange
(H) hydrogen =
white
short springs = used for making single bonds
(O) oxygen =
red
long springs
= used for making double bonds
(gently turn the springs to insert and remove)
4. Your textbook will be helpful.
5. The dotted lines next to the questions in this lab are for a teacher initial. You must have
teacher approval for each model.
6. You may construct 2 models for approval at a time. Get approval before drawing the
structure on this sheet.
7. Once your model has been approved, draw it in the space provided. Use the type of drawing
indicated here (water) as the example.
empirical
formula
H2O
structural
formula
H
O
H
8. Answer the questions on the lines provided.
How many shared electrons does one of the lines represent in the water molecule above?
_________
A. PROTEINS
Study the structure of amino acids in your textbook (pp. 78-79)
1. List the elements which may be found in proteins.
____________________________________________
2. Name the two radicals or functional groups which characterize an amino acid:
_____________________
Construct these 2 groups and draw them below.
_____________________
------------3. Construct and draw glycine and alanine. (Save these monomers to build on in the next
questions.)
------------4. Using your models from #3, construct and draw a molecule with a peptide bond. Circle the
peptide bond.
-------
6. Below are several formulas. Which one is the polypeptide? ________
How do you know?
______________________________________________________________________
______________________________________________________________________
*Use the letters to show your answer choices
A. C12H22O9N4
B. C3H7O2N
C. C5H10O2
D. C3H8O3
7. Which of these formulas is the amino acid?
E. C18H32O6
F. C12H22O11
________
How do you know?
_______________________________________________________________________
_______________________________________________________________________
B. LIPIDS
Study the structure of lipids in your textbook (p. 75)
8. Construct and draw a glycerin (glycerol) molecule.
------9. Construct and draw the fatty acid C2H4O2 . This can also be written as CH3COOH to show the
presence of a carboxyl group. Circle the part of the molecule that was attached to the glycerol.
-------
C. CARBOHYDRATES
Study the straight-chain models of simple sugars in your textbook (p. 70).
10. Construct & draw the straight chain glucose and fructose molecules: C6H12O6 . Save the
models for the next procedures.
------------11. Study the abbreviated ring structures of glucose in your textbook (p. 71). Convert the model
from #10 to a ring structure. Construct and draw the molecule.
------12. What is the name that is given to a bond between the two monomers in question #10?
____________________
13. Which of the empirical formulas in question 6 is the carbohydrate? ________
How do you know?
_____________________________________________________________________
_____________________________________________________________________