ACTIVITY VI-ORGANIC CHEMISTRY
PROTEIN MOLECULES ARE FOLDED CHAINS MADE OF TWENTY
DIFFERENT KINDS OF AMINO ACIDS AND ITS STRUCTURE DETERMINES
ITS FUNCTION.
PART I-CONCEPT ATTAINMENT GAME
PART II: MODELING PROTEIN STRUCTURE
Introduction:
Another major compound of living things is protein. Proteins make up the bulk of all
solid material within your body and other living organisms. Proteins are the most
structurally sophisticated molecules known. They vary extensively in structure with each
type of protein having a unique three-dimensional shape. Since structure determines
function proteins are well suited to carry out most of the functions in living organisms,
including growth and repair. This is the reason why scientists currently are working
furiously to determine the structure of proteins.
Proteins are complex molecules made up of smaller molecules called Amino acids. There
are about twenty different amino acids found in nature. The element nitrogen is found in
all amino acids.
Part A: Amino acids, building blocks of proteins
Examine the structural formula of the four representative amino acids below:
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1. Name the four elements present in these amino acids: _______________,
______________, _________________, ___________________
2. What is the simple formula for the amino acid?
a. glycine C ____ H ____ O ____ N____
b. alanine C ____ H ____ O ____ N ____
c. valine C ____ H ____ O ____ N ____
d. threonine C ____ H ____ O ____ N ____
3. How do the simple formulas for all of the amino acids differ? ________________
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Note the upper right corner of each amino acid. These ends have a special arrangement of
carbon, oxygen and hydrogen atoms. This type of end arrangement is called a carboxyl
group. It is circled in the diagram.
4. Draw the carboxyl group:
Note the upper left corner of each amino acid. These ends have a special arrangement of
nitrogen and hydrogen atoms. This type of end arrangement is called an amino group. A
dashed line in the diagram surrounds it.
5. Draw the amino group:
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6. Do carbohydrates have carboxyl groups? _________
7. Do carbohydrates have amino groups? __________
8. How do the numbers of hydrogen atoms compare to the number of oxygen atoms in
each amino acid? ___________________________
9. Look at the diagram, the carboxyl group and the amino group both attach to the same
central element. What is that element? ____________________
10. In all four amino acids, the central element in # 9 bonds with two other elements
other than the amino group and carboxyl group. What element does this central element
bond with that is the same in all four amino acids? ________________ (other than the
carboxyl and amino groups).
11. What is the only difference between the four amino acids? _______________
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12. Describe the general structure of an amino acid: ________________________
________________________________________________________________
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Part B: Combining amino acids to form proteins
Amino acids are not protein molecules. They are only the building blocks of proteins.
Several amino acids must be chemically bonded in a chain to form a protein molecule.
Cut out the four amino acid models included with this lab and attempt to join the amino
acids.
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13. Can the amino acid models easily join to form a protein molecule. ___________
14. What must be removed? ________________
Remove the appropriate molecule and join the amino acids in the following order:
valine - threonine - alanine - glycine
15. How many water molecules did you form? ___________
16. What is the name of this process? _____________________________
17. What chemical compound is formed when the four amino acids are joined?
________________
PART III: VIEW ANIMATIONS AND ANSWER QUESTIONS BELOW: (HONORS
ONLY)
PRIMARY STRUCTURE
SECONDARY STRUCTURE
TERTIARY STRUCTURE
QUATERNARY STRUCTURE
PROTEIN FOLDING
18. Define or describe primary, secondary, tertiary, and quaternary structure of a protein.
19. Describe the two types of secondary structure
20. What types of bonds are responsible for primary, secondary, and tertiary structure?
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