Teaching Notes
Modeling tRNA’s Translator Function
Overview:
In this activity you will make a paper models of a transfer Ribonucleic acid (tRNA) and model its
translator function.
Learning Goals:
1. Make a 3D model of transfer Ribonucleic acid (tRNA) using the template(s) provided.
2. Study the 3D model of tRNA to understand its structure and functions (e.g. codonanticodon recognition and delivering the correct amino acid).
3. Apply knowledge of the central dogma and genetic code to explore the interactions
between mRNA and tRNA and how that relates to protein synthesis
Educational Standards
A. Common Core
a. Key Ideas and Details
i. RST.11-12.3
b. Integration of Knowledge and Ideas
i. RI.11-12.7
B. Next Generation Science Standards
a. Practices
i. 2. Developing and using models
b. Crosscutting Concepts
i. 3. Scale, proportion and quantity
ii. 4. Systems and system models
iii. 6. Structure and function
c. Disciplinary Core Ideas
i. LS1.A: Structure and Function
ii. LS1.D: Information Processing
iii. PS1.A: Structure and Properties of Matter
iv. PS2.B: Types of Interactions
C. Advanced Placement Biology - Essential Knowledge (EK), Learning Objectives (LO),
Science Practices (SP)
a. EK 4.A.1
i. LO 4.2, SP 1.3
ii. LO 4.3, SP 6.1, 6.4
b. EK 4.A.2
i. LO 4.4, SP 6.4
ii. LO 4.6, SP 1.4
Teaching Notes
1. The activity is designed for a group of six to twelve students.
2. Each student (or a pair of students) will make a different tRNA model using the provided
templates. The model assembling instructions remain the same for all tRNA paper models.
3. Students compare their tRNA model with the experimentally determined on include on
the tRNA activity page.
Developed as part of the RCSB Collaborative Curriculum Development Program 2015
Teaching Notes
4. Students will work with others in the group to compare their models, answer questions
and devise a model of Translation based upon their individual models.
5. Student will present their models and how it works to the teacher and also their peers.
6. The teacher will assess each group based upon their presentation.
7. The teacher should review the concepts with their students:
a. The tRNA and mRNA interact via complementary base pairing
b. The directionality of reading the RNA strand is 5’ to 3’, while that for
proteins/peptides is N- to C.
c. The genetic code table can be used to figure out which codon will correspond to
which amino acid. The complementary sequence (read in the opposite direction) is
the anticodon sequence in that tRNA
d. There are no tRNAs that recognize the stop codons – specific proteins called
release factors bind to those sites. The binding of release factors is currently still
being actively studied.
e. The 3D folding of the tRNA exposes and facilitates the functions of its business
ends.
Developed as part of the RCSB Collaborative Curriculum Development Program 2015
Teaching Notes
Key to Questions asked in activity:
Q. What is the function of tRNA?
A. tRNA acts as a translator in the central dogma of biology – it recognizes codons in mRNA and
brings in specific and corresponding amino acids to the ribosome for protein synthesis.
Q. How many bases are in anti-codon region of the model
A. 3 bases
Q. Name of the amino acid attached to your tRNA model?
A. This will depend of the template sheet that the student has received.
Q. What is meant by “Primary structure?” (See provided instructions)?
A. This refers to the RNA sequence that forms the tRNA.
Q. What is meant by “Secondary structure?” (See provided instructions)?
A. This refers to organization of the tRNA sequence with the formation of local regions of basepairing. This state is often referred to as the clover-leaf shape with acceptor, TC, D and
anticodon arms.
Q. What is meant by “Tertiary structure?” (See provided instructions)?
A. This refers to the organization of the 3D shape of tRNA forming the inverted L-shaped
structure. In this conformation the two business ends of the molecule are available for their
functions.
Q. Can you locate the anticodon region and amino acid attachment sites? What color(s) are they?
A. red
Q. What do the other colored regions in the models represent?
A. Acceptor, TC, and D arms
Q. What is the anticodon in your tRNA model? Write the sequence here.
A. The answers are given with Phe as the example – anticodon sequence is GAA
Q. Write the mRNA codon that matches your anti-codon?
A. UUC
Q. Which amino acid is usually at the start of a synthesized peptide/protein? What is its codon?
A. Methionine, AUG.
Q. What happens when the stop codon is read by the ribosome? (Hint: Read the Molecule of the
Month article on Ribosomes for clues http://pdb101.rcsb.org/motm/121)
A. A release factor binds to the stop codon to end the protein synthesis of that chain – there is no
tRNA that binds to stop codons.
Q. Create a strand of mRNA that your tRNA’s can decode. Use each tRNA only once. Write down
the mRNA sequence and the protein sequence below.
Developed as part of the RCSB Collaborative Curriculum Development Program 2015
Teaching Notes
A. Possible mRNA sequence is:
AUG-AAG–CCG-CUA-UUC-CGC-UAA
Corresponding peptide made is:
Met-Lys-Pro-Leu-Phe-Arg
Q. Final Reflection: How does the real tRNA structure (from the model and the webpage)
compare to how RNA is explained in textbooks?
A. Based in the textbooks you use – assess the student response.
Developed as part of the RCSB Collaborative Curriculum Development Program 2015