Video Transcript
Fill in the blank. An anticodon is the complementary sequence to a codon in mRNA that is found in
blank. (A) Amino acid, (B) tRNA, (C) rRNA, (D) DNA, (E) siRNA.
This question is asking us about anticodons, which is a feature of translation of
mRNA. Let’s first review translation in some detail to answer our question.
In order for a gene in DNA to be converted into a protein, it needs to go through a
couple of steps. The first step is called transcription, and this is where DNA is copied to form
mRNA. The sequence of nucleotides in mRNA is then translated into a sequence of amino acids
to form a polypeptide, which can then fold into a protein. During translation, the ribosome binds to mRNA.
You may recall that mRNA is read by the ribosome in three nucleotide segments called
codons. Here you can see three codons indicated. These codons correspond to specific amino acids. For instance, the codon AUG corresponds to the amino acid methionine. These amino acids are brought in to the ribosome by a special type of RNA called
transfer RNA, or tRNA. These tRNAs can bind to these codons because they themselves contain an anticodon
sequence that is complementary to the codon sequence in mRNA.
There are many different tRNA molecules, each with different anticodons to match
codons with specific amino acids. The ribosome is able to move along the mRNA sequence and match the codons to the
corresponding amino acids brought in by the tRNAs. It can then link them together to form a polypeptide chain, which can then go on to
fold into a protein.
So, to answer our question, in the statement “an anticodon is the complementary
sequence to a codon in mRNA that is found in blank,” the option that correctly fills
in the blank is given by answer choice (B), tRNA.
