Molecular Biology: Translation, tRNA, and Ribosomal Function

What are the roles of ribosomes, mRNA, and tRNAs in translation?

Ribosomes facilitate the translation of mRNA into protein by providing a site for tRNA to bring amino acids, which are linked together to form a polypeptide.

How does translation differ between bacteria and eukaryotes?

In bacteria, translation occurs while mRNA is being synthesized by RNA polymerase, while in eukaryotes, translation occurs after mRNA processing and transport out of the nucleus.

What is the function of transfer RNA (tRNA) in protein synthesis?

tRNA transports specific amino acids to the ribosome and matches them to the corresponding codon on the mRNA during translation.

How are amino acids attached to tRNAs?

Amino acids are attached to tRNAs by specific enzymes called aminoacyl-tRNA synthetases, which ensure the correct amino acid is linked to its corresponding tRNA.

What is the wobble hypothesis?

The wobble hypothesis explains that the third position of a codon can vary and still code for the same amino acid, allowing for some flexibility in base pairing between tRNA and mRNA.

What are the main events of translation initiation?

Translation initiation involves the binding of mRNA to the small ribosomal subunit, the attachment of the initiator tRNA to the start codon, and the assembly of the large ribosomal subunit.

What occurs during translation elongation?

During elongation, aminoacyl tRNA enters the ribosome, a peptide bond forms between the amino acids, and the ribosome translocates to the next codon.

What is the process of translation termination?

Translation termination occurs when a stop codon is reached, leading to the release factor binding, which causes the polypeptide to be released from the tRNA and the ribosome disassembles.

What is post-translational modification?

Post-translational modification refers to the chemical changes that occur to a polypeptide after translation, which can affect its function, stability, and localization.

What is the significance of codon-anticodon recognition?

Codon-anticodon recognition ensures that the correct amino acid is incorporated into the growing polypeptide chain, maintaining the fidelity of protein synthesis.

What is the role of the release factor in translation termination?

The release factor is a protein that binds to the stop codon in the A site of the ribosome, triggering the release of the newly synthesized polypeptide.

What happens to a newly synthesized polypeptide after translation?

After translation, the polypeptide may undergo folding and post-translational modifications to become a functional protein.

What are the tRNA binding sites in the ribosome?

The ribosome has three tRNA binding sites: the A (aminoacyl), P (peptidyl), and E (exit) sites, which facilitate the binding and release of tRNAs during translation.

How do mutations in the anti-codon of tRNA affect protein synthesis?

Mutations in the anti-codon of tRNA can lead to incorrect amino acids being incorporated into a protein, potentially altering its structure and function.

What is the coding strand of DNA that corresponds to the codon for leucine (5'-CUG-3')?

The coding strand of DNA that encodes the codon for leucine is 5'-CAG-3'.

What is the anticodon of tRNA that recognizes the codon for leucine (5'-CUG-3')?

The anticodon of tRNA that recognizes the codon for leucine is 3'-GAC-5'.

What is the role of initiation factors in translation initiation?

Initiation factors assist in the assembly of the ribosome and the binding of the mRNA and initiator tRNA to the small ribosomal subunit.

What is the first amino acid incorporated during translation initiation in eukaryotes?

The first amino acid incorporated during translation initiation in eukaryotes is methionine, often represented as f-Met.

What is the significance of the start codon in translation?

The start codon (AUG) signals the beginning of translation and codes for the first amino acid, methionine.

What is the function of the endomembrane system in relation to proteins?

The endomembrane system helps in the processing, folding, and transport of proteins within the cell.

What happens when RNA Polymerase II encounters a stop codon during transcription?

When RNA Polymerase II encounters a stop codon, it terminates transcription, releasing the newly synthesized mRNA.