Section 1: In a eukaryotic cell, mRNA must be exported from the nucleus before it can be translated. In contrast, the bacterial processes of transcription and translation are tightly coupled. Ribosomes initiate translation at ribosome binding sites that are usually near the 5' end (the end synthesized first) of the mRNA. Refer to Figure 18-5.
Section 2: Initiation factors and a charged initiating tRNA are needed before the 50S subunit can be assembled with the 30S. The tRNA builder is at the upper left. For the initation complex, one needs a particular charged tRNA with a specialized initiating amino acid residue (one that is modified relative to the standard 20 amino acids) attached to it. Refer to Figure 18-18 for initiation factors.
Section 3: Use the tRNA builder at the upper left for each new amino acid to be added. Note that you will need the genetic code to figure out the anticodon sequences. The sequence to be used is complementary to the codon. Note also the 3' to 5' orientation of the anticodon sequence in the tRNA builder. An elongation factor is required for translocation after each tRNA addition. The peptide should be elongated with new amino acid residues until you come to a stop codon. Note that the role of elongation factor Tu is not modeled in this simulation. For details on Ef-Tu, see the textbook Figure 18-23. Refer to Figure 18-26 for elongation factors.
Section 4: When you reach a stop codon, load the termination and recycling factors in the correct order. Refer to Figures 18-27 and 18-29 for termination and recycling factors.
Complete all four sections before taking the Tutorial Comprehension Quiz.
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Prerequisite skills needed:
RNA Structure
Relevant book section: pages 630-647
By completing this simulation, you will:
Understand the chemical reactions of translation
Understand the sequence of events and process of translation
Build a bacterial ribosome
Translate a portion of mRNA
Terminate translation and recycle the ribosome
Translation - Introduction to Polysomes
Before we get startedWhat system is depicted here?
Peptide Bond Formation This is the first time you have created a peptide bond. In our simulation, this step has been simplified. To see the details, please click Peptide Bond Formation below. Click Dismiss to continue with the activity.
InstructionsYour task in this simulation is to translate this mRNA. Begin by assembling the initiation complex on the transcript. Drag and drop the appropriate molecules to the correct area to assemble the complex. Hint: The small subunit of the ribosome requires additional factors before it can associate with mRNA. Also, if you need any tRNA molecules, please click on the red amino acid to activate the tRNA builder.
Congratulations Now that you have assembled the initiation complex, use the tRNA builder and the shown molecules to elongate the amino acid chain. When appropriate, terminate the translation process and recycle the ribosome.
Congratulations You have successfully completed this activity!
Amino Acid (ex. ALA)
3'--5'
Anti-Codon (ex. GAA)
Not Valid
Not Valid. Try fMet instead.
RNA Processing - Simulation Results
Your Answer:
Correct Answer:
NOTE: This is not the actual sequence of the BRCA-II gene, but rather just a random sequence created for this exercise.
Results:
Congratulations! You figured out the sequence based on the chromatogram. If you would like to try the exercise again with a new dna sequence, please click the button below.
Results:
Sorry, you selected the wrong nucleotides. If you would like to try the exercise again with a new dna sequence, please click the button below.
