Video Transcript
The diagram provided shows the
stages of translation in an incorrect order. Order the stages correctly. (A) W to V to Z to Y to X, (B) V to
Z to W to Y to Z, (C) V to Z to Y to X to W, (D) W to X to Z to V to Y, (E) Z to W
to V to Y to X.
In order for a gene in DNA to be
converted into a protein, it needs to go through two steps. The first step is called
transcription, and it produces mRNA. The second step is called
translation, where the sequence of mRNA is converted into a sequence of amino acids
to form a polypeptide. To do this, three nucleotide
sequences within mRNA, called codons, are matched with their corresponding anticodon
sequence on tRNA molecules that carry specific amino acids.
Let’s go over the steps of
translation in detail to see this in action and to answer our question.
First, the small subunit of the
ribosome binds to mRNA. This is indicated by step W. Then, the small subunit scans the
mRNA until it finds a start codon, which codes for the amino acid methionine. A tRNA molecule that’s carrying a
methionine amino acid binds to the mRNA through its anticodon. Then, the large ribosomal subunit
joins. This corresponds to step V. Then, a tRNA carrying the next
amino acid binds to the next mRNA codon using its corresponding anticodon.
Now, the ribosome can bring
together the two amino acids to form a peptide bond using the peptidyl transferase
activity of the large subunit. This forms a polypeptide. This step is shown in step Z. Next, the ribosome moves along the
mRNA, and the first tRNA can leave the ribosome. And now the next tRNA with the next
amino acid can bind to the ribosome. This is indicated in step Y. Steps Z and Y repeat as the
polypeptide chain grows. This goes on until the ribosome
reaches a stop codon which causes translation to terminate and the polypeptide and
mRNA are released. So step X is the final step. And now we can answer our
question.
The correct order for the stages of
translation is given by answer choice (A): W to V to Z to Y to X.
