Question

The functional product of a protein-encoding gene is a. tRNA. b. \(\mathrm{mRNA}\) c. rRNA. d. a polypeptide. e. \(a, b,\) and \(c\)

Short answer

The functional product of a protein-encoding gene is a polypeptide.

Step-by-step solution

Understand the Question

This question is asking for the final product produced by a protein-encoding gene. Knowing the process of gene expression will help answer this question.

Identify the RNA Types

The choice includes tRNA (transfer RNA), mRNA (messenger RNA) and rRNA (ribosomal RNA). These are all important in protein synthesis, but they are not the final product.

Choose the Correct Answer

The correct answer is a polypeptide. A polypeptide chain is produced during translation, which is the last part of gene expression. This chain will eventually fold into a protein, making it the functional product of a gene.

Key concepts

Protein Synthesis

Protein synthesis is a fundamental biological process that takes the genetic instructions stored in DNA and converts them into functional proteins. This process occurs in two main stages: transcription and translation.
During transcription, the DNA sequence of a gene is copied into messenger RNA (mRNA). This step is crucial because mRNA serves as a template that carries the genetic information from the DNA in the nucleus to the ribosomes, the site of protein synthesis in the cell's cytoplasm.
Once the mRNA is transcribed, it undergoes translation at the ribosome. Here, the genetic code on the mRNA is read by the ribosome, and with the help of transfer RNA (tRNA), it assembles amino acids into a specific sequence, forming a polypeptide chain. The sequence of amino acids determines the structure and function of the resulting protein, highlighting the significance of precise protein synthesis.

Polypeptide

A polypeptide is essentially a chain of amino acids linked together through peptide bonds, and it serves as a precursor to proteins. This chain is created during the translation phase of protein synthesis.
The ribosome reads the sequence of codons on the mRNA, each of which specifies a particular amino acid. tRNA molecules transport the correct amino acids to the ribosome, following the instructions encoded in the mRNA.
Polypeptides are not functional proteins yet. They must fold into a specific three-dimensional structure to become active. This folding is crucial because the shape of a protein determines its function in the body. Various cellular organelles and mechanisms assist in this folding process, ensuring that the protein achieves the correct configuration.
Thus, polypeptides play a vital role as intermediates that eventually become functional proteins, driving countless cellular functions.

RNA Types

RNA comes in several forms, each of which plays a unique and crucial role in the process of protein synthesis. The three main types are:

• mRNA (messenger RNA): This type of RNA carries the genetic blueprint from DNA to the ribosome, where proteins are synthesized. It serves as a template for the sequential addition of amino acids.
• tRNA (transfer RNA): tRNA is responsible for bringing the appropriate amino acids to the ribosome, matching each mRNA codon with the correct amino acid during translation.
• rRNA (ribosomal RNA): rRNA, a key component of the ribosome, aids in the catalytic functions of the ribosome and helps in the alignment of mRNA and tRNA, facilitating the translation process.

These RNA types work collaboratively to ensure the precise synthesis of proteins, demonstrating the intricacy and coordination involved in gene expression.