Lab: Building Proteins from RNA
Student Guide
Prelab Information
Purpose
Explore the molecular process of building proteins from the information carried by RNA
using a laboratory procedure.
Time
Approximately 45 minutes
Question
How are proteins built using the information provided by a molecule of RNA?
Prediction
RNA determines the sequence of amino acids in proteins and polypeptides by a twostep process: transcription of DNA produces mRNA in the nucleus, then translation
of the mRNA to tRNA takes place at the ribosome in the cytoplasm.
Lab Procedure
Materials:
 helicase
 human cell


 tRNA sequence
 protein structure chart
Step 1: Transcribe the Information in DNA to mRNA
(The animation will zoom from the human cell to the nucleus to the DNA strand.)
a) Find and click the arrow that represents the direction in which the mRNA is built. Like DNA,
mRNA is always built from the 5' direction to the 3'.
b) Which RNA nucleotide can pair with the thymine (T) at the beginning of the strand? Drag it into
the DNA antisense strand to make a pair.
c) Complete nine (9) additional base pairs. Remember, there is no thymine (T) in RNA. The
adenine (A) in the DNA needs to pair with uracil (U).
d) After your mRNA sequence record is complete, click “Leave the Nucleus” to send the mRNA
to the ribosome in the cell’s cytoplasm, where production of proteins will take place.
Step 2: Locate Codons
(You will continue to read mRNA from the 5′ end toward the 3′ end.)
a) A codon is a sequence of three bases that indicates a unit of information in the RNA. A gene is a
series of codons that results in the production of a protein. Identify the codons of the mRNA
shown. The start codon for a gene is AUG, so start by dragging the blue start codon box over the
AUG on the strand. (The start codon is already recorded on the data table.)
b) Use the gray codon box to highlight additional codons three bases at a time. When you reach
a stop codon (either UAA, UAG, or UGA) you will need to use the pink stop codon box. As you
form codons, record them in Table 1.
Step 3: Translate mRNA
tRNA is composed of short sections of RNA that bond to the codons in mRNA. The screen shows a
pool of tRNA anticodons, which carry the amino acids to the ribosome and attach to the mRNA
when its sequence of base pairs is complementary with the mRNA in the ribosome.
a) For each codon, you will find the correct tRNA anticodon and drag it to the ribosome. Start with
the AUG codon in the ribosome. Find and drag its match, the UAC anticodon, to it. Record this
Copyright © Edgenuity Inc.
Student Guide (continued)
pair and the amino acid Met to complete the first row of Table 2.
b) Find the next anticodon you need to match the next mRNA codon you identified. Drag its
anticodon to the ribosome. Record in the second row of Table 2.
c) Remember, the ribosome can only handle two tRNA strands at a time. So, click the Dehydrate
button to activate the process of dehydration synthesis, or the loss of water molecules
during protein building.
d) Continue to build the protein by joining amino acids to the chain in the correct order. Every amino acid
joined to the protein results in the production of one more water molecule. Click Dehydrate to form the
peptide bonds. W atch the water molecule counter and be sure to record all data in your data Table 2.
When many amino acids are joined in sequence, this is a polypeptide chain.
Copyright © Edgenuity Inc.
Student Guide (continued)
Sequence and Protein Structure Chart
Image: Public domain. http://commons.wikimedia.org/wiki/File:Aminoacids_table.svg
Copyright © Edgenuity Inc.
Student Guide (continued)
Data
Table 1: Codon sequences for mRNA molecule
Codons
AUG (start)
Copyright © Edgenuity Inc.
Student Guide (continued)
Data
Table 2: Translation of mRNA molecules
Codons
AUG (start)
Copyright © Edgenuity Inc.
tRNA Anticodons
Amino Acid
Number of Water
Molecules
Produced