Question

imagine you are an oncologist (cancer doctor). you are trying to understand more about the cancerous cells in a recent tumor sample from a patient. you suspect that the machinery that splices pre - mrnas is not working correctly.
drag and drop the events in order to show how defects in the splicing machinery could lead to the phenotype of cancer.

• the mature mrna contains rna sequences beyond exon sequences.
• after being transcribed, the introns are not removed from an mrna.
• during translation, the ribosome binds to a different place than the typical start codon.
• the protein made from translation functions slightly differently in the cell because its structure is atypical.
• during translation, the sequence of amino acids added to the growing protein is different than in typical noncancerous cells.

Explanation:

To determine the order, we analyze the process of RNA splicing and its impact on translation and protein function:

Step 1: Identify the initial defect

The problem states the splicing machinery is not working correctly. The first event should be the cause of the splicing defect. "After being transcribed, the introns are not removed from an mRNA" is the initial step as it describes the failure of the splicing machinery to remove introns.

Step 2: Consequence of intron retention

If introns are not removed, the mature mRNA will contain sequences beyond the exons (introns are non - coding sequences that should be removed). So "The mature mRNA contains RNA sequences beyond exon sequences" is the next step.

Step 3: Impact on translation start

With an abnormal mRNA, during translation, the ribosome will bind to a different place than the typical start codon. This is because the abnormal mRNA sequence (with introns) will affect the ribosome binding site. So "During translation, the ribosome binds to a different place than the typical start codon" follows.

Step 4: Effect on amino acid sequence

If the ribosome binds at a different start codon, the sequence of amino acids added to the growing protein will be different than in typical non - cancerous cells. So "During translation, the sequence of amino acids added to the growing protein is different than in typical noncancerous cells" is the next event.

Step 5: Final effect on protein function

A different amino acid sequence will lead to a protein with an atypical structure, and thus the protein made from translation will function slightly differently in the cell. So "The protein made from translation functions slightly differently in the cell because its structure is atypical" is the last step.

Answer:

1. After being transcribed, the introns are not removed from an mRNA
2. The mature mRNA contains RNA sequences beyond exon sequences
3. During translation, the ribosome binds to a different place than the typical start codon
4. During translation, the sequence of amino acids added to the growing protein is different than in typical noncancerous cells
5. The protein made from translation functions slightly differently in the cell because its structure is atypical