MnSTEP Teaching Activity Collection > MnSTEP Activities > Building A Protein

Building A Protein

Bonnie Stevenson-Tapper
AGAPE High School, Saint Paul, Minnesota.
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Summary

This hands-on activity is an assessment of the students understanding of peptide and disulfide bonds formed during protein synthesis, and the structure of an amino acid (R-group plus the common structure that all amino acids share). Students will demonstrate the process of dehydration synthesis by combining amino acids. They will synthesize one molecule of the protein ADH (antidiuretic hormone) by reading the mRNA sequence, cutting out the -OH on the carboxyl group on amino acid one, and the -H on the amino group of amino acid two. These two pieces (-OH and -H) will combine to form a water molecule. The students will connect the two amino acids by taping a peptide bond label between the carbon of the carboxyl and the nitrogen of the amino group on amino acid. This process is continued until the stop codon on the mRNA is read. If the synthesis is done correctly, the student will produce eight peptide bonds creating one chain, and eight molecules of water. If this activity is used for biology, the tRNA, and rRNA molecules can be added to the process.

Learning Goals

This activity is designed for students to demonstrate the concepts of bonding amino acids to create proteins, and to model protein synthesis.
Concepts:
Chemistry
Describe the basic structure of amino acids and the formation of polypeptides.
The interaction of amino acid side chains determine the shape and structure of the protein.
Biology
Translation converts mRNA into a protein using amino acids found in the cytoplasm.

Vocabulary:
Chemistry
-Amino acid
-Bond
-Carboxyl group
-Dehydration
-Protein
-Synthesis

Biology
-Anticodon
-mRNA
-Protein synthesis
-Start codon
-Stop codon
-Translation
-tRNA

Context for Use

This activity is a high school level assessment tool that ties both biology and chemistry together. It can be used in a biology class as an assessment of translation, or as a chemistry class assessment of biological bonds. The students may need instructions and guidance to assemble the pieces, but the end product will visually demonstrate the students understanding of the process of dehydration synthesis and the two types of bonds (peptide and disulfide between the two cystine amino acids). Students that are not able to begin the protein synthesis may be guided through the bonding process, but by the 4th bond they should be able to explain the process and manipulate the formation of the protein. This visual produce may be used along with a worksheet with some high end questioning. The only required skills are cutting, and taping paper together.

Subject: Biology:Molecular Biology, Chemistry:Organic Chemistry, General Bonding & Molecules
Resource Type: Activities:Classroom Activity:Short Activity:Demonstration, Activities:Classroom Activity
Grade Level: High School (9-12)

Description and Teaching Materials

Materials:
Amino Acid Template worksheet (one per student)
mRNA Seq Template
1 Scissor, and 1 roll of tape.
(Biology may add tRNA
One codon translation table or codon translation wheel.


Preparation:
  1. Assemble the strand of mRNA.
    Cut along the solid lines and tape the three strips of paper together. The second strip that begins with "glu" should be taped to strip number one that ends in "phe". Then tape strip number three that begins with "gly" to strip number two that ends with "arg". You should have one strip of paper with eleven mRNA codons.
  2. Assemble the amino acids.
    Cut along the solid lines on the Specific Amino Acid worksheet. You will have nine amino acid cards. Then cut out the nine R-groups. Tape one amino acid to one r-group card to create nine specific amino acids.
  3. Cut out the nine bonds and the eight process labels.

Activity:
  1. Using your translation table read two codons following the start codon.
  2. Find the amino acid cards that match these codons.
  3. Perform dehydration synthesis to link the two amino acids together.
    1. Cut out the -OH on the carboxyl group on the first amino acid.
    2. Cut out the -H on the amino acid on the second amino acid.
    3. Combine these two piece (-OH and -H ) to form a water molecule.
    4. Tape a peptide bond label between the carbon of the first amino acid and the nitrogen of the second amino acid.
    5. Lay the dehydration synthesis label below the peptide bond, and above the water molecule.
  4. Read and translate the next mRNA codon.
  5. Perform dehydration synthesis on the last amino acid of your polypeptide chain, and the new amino acid until you read the stop codon.
  6. Now tape the disulfide bond between the two cystine amino acids.

Closure:
This can be done verbally or written.
  1. Have the students describe dehydration synthesis process including the words dehydration synthesis, and peptide bond.
  2. Explain why there is only one disulfide bond in this chain, and what happens to the protein when the disulfide bond occurs.
Amino Acid Templates (Microsoft Word 58kB Aug15 08) mRNA Template (Microsoft Word 24kB Aug15 08)

Teaching Notes and Tips

When I have used this activity I found students that understand the process can get through the assembly quickly and they tend to help the students that are struggling. So what starts out as an individual project turns into a peer teaching experience. This helps my visual and tactile learners animate their book vocabulary. It also makes those students that understand written concepts verbalize their knowledge. I like to do this activity at the end of the unit before a written quiz or test. I found it is best to "see" where the students get hung up before trying to assess their knowledge with a graded assignment.

Assessment

The student should produce a physical chain with labels,and the eight water molecules products of the hydration synthesis.

Standards

MN 9-12.IV.B.4.1
Ionic Bonds
MN 9-12.VI.D.6.1
Identify synthesis reaction
MN 9-12.IV.D.1.2
Relationships DNA, Genes, Chromosome.

References and Resources

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