Question

If a messenger RNA codon is UAC, which of the following would be the complementary anticodon triplet in the transfer RNA? (A) ATG (B) AUC (C) AUG (D) ATT (E) ATC

Short answer

The transfer RNA anticodon that complements the messenger RNA codon UAC is AUG. Therefore, the answer is (C) AUG.

Step-by-step solution

Understand the Base Pairing Rules in RNA

In RNA, Adenine (A) pairs with Uracil (U) and Cytosine (C) pairs with Guanine (G), just like as in DNA, Cytosine pairs with Guanine and Adenine pairs with Thymine.

Pairing the Bases

Given that the messenger RNA (mRNA) codon is UAC, one should exchange each nitrogenous base with its pair according the base pairing rules mentioned above. Therefore, the first base 'U' in mRNA pairs with 'A' in tRNA, second base 'A' pairs with 'U' and third base 'C' pairs with 'G'

Identify the Correct Anticodon

The anticodon triplet in the tRNA which is complementary to the given mRNA codon UAC would be AUG.

Key concepts

tRNA

Transfer RNA, or tRNA, is an essential molecule in the process of translation, which occurs in protein synthesis. It serves as the link between the mRNA and the amino acids that form proteins. Each tRNA molecule carries a specific amino acid, which is determined by its anticodon. The anticodon is a set of three nucleotides on the tRNA that pairs with a complementary mRNA codon. This matching process ensures that the correct amino acids are added to the growing protein chain.

The tRNA structure resembles a cloverleaf, with several loops and stems. The anticodon is on one loop, while the opposite end of the tRNA connects to the amino acid. This structure allows it to precisely fit into the ribosome, facilitating the decoding of mRNA into proteins.

• tRNA is crucial for translating genetic codes into proteins.
• It carries specific amino acids to the ribosome.
• The tRNA anticodon pairs with mRNA codons.

base pairing

Base pairing is a fundamental concept in genetics, crucial for the transfer of genetic information from DNA to RNA and ultimately to proteins. In the context of RNA, base pairing refers to the specific hydrogen bonding between nucleotides in mRNA and tRNA during translation.

In RNA, adenine (A) pairs with uracil (U) instead of thymine, which is used in DNA. Cytosine (C) consistently pairs with guanine (G), both in DNA and RNA. This complementary base pairing is essential for maintaining the integrity of genetic information as it is transcribed and translated in the cell.

• Base pairing maintains the fidelity of genetic codes during translation.
• In RNA, the pairs are A-U and C-G.
• Efficient base pairing ensures accurate protein synthesis.

anticodon

An anticodon is a sequence of three nucleotides on a tRNA molecule that is complementary to an mRNA codon. The anticodon-codon pairing is precise and essential for accurately translating genetic information from mRNA into amino acid sequences. As each tRNA carries a specific amino acid corresponding to its anticodon, the accurate pairing ensures the correct amino acid is incorporated into the protein chain.

For example, if the mRNA codon is UAC, the complementary anticodon on the tRNA would be AUG. This matching allows for the precise addition of the amino acid methionine, which AUG codes for.

• Anticodons are complementary to mRNA codons.
• They ensure the correct amino acid sequence in proteins.
• Precise pairing is critical for protein function.

codon

A codon is a sequence of three nucleotides on the mRNA molecule that encodes a specific amino acid. During the process of translation, codons are read by the ribosome with the help of tRNA molecules. Each set of three bases—known as a codon—corresponds to an amino acid or a stop signal for protein synthesis.

There are 64 possible codons in the genetic code, which include 61 that code for amino acids and 3 stop codons. The redundancy in the codon system means that multiple codons can code for the same amino acid, providing a buffer against mutations.

• Codons are sequences of three nucleotides in mRNA.
• They dictate the amino acid sequence of proteins.
• The genetic code is degenerate, meaning some amino acids are coded by more than one codon.