Question

second position
first position (5 end) u (u, c, a, g columns) c (u, c, a, g columns) a (u, c, a, g columns) g (u, c, a, g columns) third position (3 end) (u, c, a, g rows)
u row: uuu (phe), uuc (phe); ucu (ser), ucc (ser), uca (ser), ucg (ser); uau (tyr), uac (tyr), uaa (stop), uag (stop); ugu (cys), ugc (cys), uga (stop), ugg (trp)
c row: cuu (leu), cuc (leu), cua (leu), cug (leu); ccu (pro), ccc (pro), cca (pro), ccg (pro); cau (his), cac (his), caa (gln), cag (gln); cgu (arg), cgc (arg), cga (arg), cgg (arg)
a row: auu (ile), auc (ile), aua (ile), aug (met, start); acu (thr), acc (thr), aca (thr), acg (thr); aau (asn), aac (asn), aaa (lys), aag (lys); agu (ser), agc (ser), aga (arg), agg (arg)
g row: guu (val), guc (val), gua (val), gug (val); gcu (ala), gcc (ala), gca (ala), gcg (ala); gau (asp), gac (asp), gaa (glu), gag (glu); ggu (gly), ggc (gly), gga (gly), ggg (gly)
initiation (yellow), termination (light blue)
will she likely get a protein with the desired sequence when this mrna is translated in the test tube?

• no. the mrna is missing a stop codon, so the protein will be much longer than the desired protein.
• no. the mrna has 8 codons but the desired protein only has 7 amino acids.
• no. the mrna is missing a start codon, so translation will never initiate.
• yes. this mrna codes for the amino acids in the desired protein.

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Explanation:

To determine the correct answer, we analyze each option:

1. Option 1: If the mRNA is missing a stop codon, translation would continue past the desired sequence, making the protein longer. This is a key concept in translation (protein synthesis) where a stop codon (UAA, UAG, UGA) signals the end. If absent, ribosomes don't stop, leading to a longer protein.
2. Option 2: Codons code for amino acids, and the number of codons (excluding stop) should match the number of amino acids. But the main issue here is not the count mismatch but the lack of a stop codon (if that's the case). However, the first option's reasoning about the stop codon is more critical for protein length.
3. Option 3: The mRNA has AUG (start codon, as seen in the codon table), so translation can initiate. Thus, this is incorrect.
4. Option 4: Without a stop codon, the protein won't terminate at the desired length, so this is incorrect.

The first option correctly explains that a missing stop codon causes the protein to be longer than desired.

Answer:

No. The mRNA is missing a stop codon, so the protein will be much longer than the desired protein.