Question

Given the following molecule of DNA: strand \(1-\mathrm{A} \mathrm{T} \mathrm{G} \mathrm{C} \mathrm{G} \mathrm{C} \mathrm{T} \mathrm{A} \mathrm{C} \mathrm{G} \mathrm{G} \mathrm{C} \mathrm{A} \mathrm{A} \mathrm{T}-\) strand \(2-T A C G C G A T G C C G T T A-\) Determine the \(\mathrm{mRNA}\) molecule, the tRNA anticodons, and the amino acid sequence that will be produced if strand 1 is the transcription template for the mRNA molecule.

Short answer

The mRNA sequence synthesized from the given DNA strand is 'U A C G C G A U G C C G U U A'. The corresponding tRNA anticodons are 'A U G C G C U A C G G C A A U'. The amino acid sequence produced from this mRNA sequence is Tyrosine-Alanine-Methionine-Proline-Leucine.

Step-by-step solution

Steps for mRNA synthesis from the DNA strand

To convert the DNA strand into an mRNA sequence, follow the base-pairing rules of transcription: 'A' pairs with 'U', 'T' pairs with 'A', 'G' pairs with 'C', and 'C' pairs with 'G'. Thus, the mRNA sequence synthesized from the provided DNA strand is 'U A C G C G A U G C C G U U A'.

Steps for tRNA Anticodon formation

tRNA anticodons are formed by matching the bases of the mRNA sequence, 'U' pairs with 'A', 'A' pairs with 'U', 'C' pairs with 'G', and 'G' pairs with 'C'. So, the tRNA anticodons corresponding to the mRNA are 'A U G C G C U A C G G C A A U'.

Determining the Amino acid sequence

Finally, the mRNA sequence represents a series of codons, each of which codes for a specific amino acid. We now determine the amino acid sequence encoded by our mRNA sequence. When read in groups of three (codons), the mRNA sequence produced corresponds to the amino acids: 'UAC'=Tyrosine, 'GCG'=Alanine, 'AUG'=Methionine, 'CCG'=Proline, 'UUA'=Leucine. So, the sequence of corresponding amino acids is Tyrosine-Alanine-Methionine-Proline-Leucine.

Key concepts

mRNA Synthesis

The central dogma of molecular biology describes the flow of genetic information from DNA to RNA to proteins. One of the critical steps in this process is the synthesis of messenger RNA (mRNA) from a DNA template, known as transcription. During transcription, certain enzymes, including RNA polymerase, bind to the DNA molecule. As they move along one strand of the DNA helix, they use it as a template to assemble a single-stranded RNA molecule with complementary bases. Unlike DNA, RNA uses uracil (U) instead of thymine (T).

For example, if we have a DNA template strand with a sequence of ATGCGCTACGGCAAT, we would apply the base-pairing rules to create the mRNA sequence. Adenine (A) pairs with uracil (U), thymine (T) pairs with adenine (A), guanine (G) pairs with cytosine (C), and cytosine (C) pairs with guanine (G). Therefore, the mRNA strand synthesized from our example DNA template would be UACGCGAUGCCGUUA.

tRNA Anticodons

Transfer RNA, or tRNA, is the adaptor molecule that decodes the mRNA sequence into an amino acid sequence during translation. Each tRNA molecule has an anticodon, a set of three nucleotides that are complementary to an mRNA codon. The tRNA anticodon and mRNA codon pairing is crucial for adding the correct amino acid to the growing polypeptide chain.

In the mRNA sequence UACGCGAUGCCGUUA, each triplet codon corresponds with an anticodon on the tRNA. According to the base-pairing rules, where uracil (U) pairs with adenine (A) and guanine (G) pairs with cytosine (C), the tRNA anticodons would be AUG (for UAC), CGC (for GCG), UAC (for AUG), GGC (for CCG), and AAU (for UUA). These anticodons ensure the appropriate amino acids are transported by the tRNA to the ribosome for protein synthesis.

Amino Acid Sequence

Translation is the process through which the sequence of nucleotides in mRNA is decoded into a sequence of amino acids, resulting in the formation of a polypeptide chain—essentially, a protein. Each group of three nucleotides in mRNA forms a codon, with each codon signifying a specific amino acid or a stop signal for translation.

For our example mRNA sequence UACGCGAUGCCGUUA, we identify the corresponding amino acids by their codons: Tyrosine (UAC), Alanine (GCG), Methionine (AUG), Proline (CCG), and Leucine (UUA). Hence, the complete amino acid sequence formed from the mRNA is Tyrosine-Alanine-Methionine-Proline-Leucine. This sequence is the primary structure of a protein and will further fold and assume complex structures performing various functions within the cell.