mRNA Translation, Protein Synthesis & Mutations in Genetics

What is the role of ribosomes in protein synthesis?

Ribosomes translate the nucleotide sequence of mRNA into a specific amino acid sequence, producing proteins.

What is the first step of the translation process?

Initiation, where the ribosome binds to the initiator tRNA carrying the initiating amino acid and scans for the AUG start codon.

What happens during the elongation phase of translation?

New tRNA carrying an amino acid enters the A site of the ribosome, and a peptide bond is formed between adjacent amino acids.

What triggers termination in the translation process?

The presence of a stop codon in the A site, which is recognized by a release factor, leading to the release of the polypeptide.

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

tRNA brings specific amino acids that match each codon in mRNA through complementary anticodons.

What are post-translational modifications?

Chemical modifications that occur to proteins after translation, affecting their activity, localization, and stability.

What is phosphorylation in the context of post-translational modifications?

The addition of a covalently bound phosphate group to an amino acid residue, which is a widespread type of PTM.

What is glycosylation?

The attachment of sugar moieties to proteins, critical for various biological processes.

What is a point mutation?

A mutation where one nucleotide in DNA changes, leading to a nucleotide change in RNA and potentially altering the protein.

What is a frameshift mutation?

A mutation caused by the addition or deletion of a base in the DNA sequence, altering the reading frame of RNA.

What are nonsense mutations?

Mutations that result in a stop codon in the RNA sequence, prematurely terminating protein synthesis.

What is a silent mutation?

A mutation that does not affect the protein at all.

What is a conservative mutation?

A mutation where the new amino acid is of the same type as the original.

What is a non-conservative mutation?

A mutation where the new amino acid is of a different type than the original.

What are missense mutations?

Mutations that change one amino acid to another in the protein sequence.

How do mutations affect proteins?

Mutations originate at the DNA level but show their effects at the protein level, potentially altering structure and function.

What is ubiquitination?

The attachment of the polypeptide ubiquitin to target proteins, marking them for degradation.

What is acetylation?

The process where an acetyl group from acetyl coenzyme A (Ac-CoA) is transferred to a specific site on a protein.

What is the significance of the A-site in ribosomes?

The A-site is where tRNA carrying the next amino acid enters and matches with the codon on mRNA.

What occurs in the P-site of the ribosome?

The P-site holds the tRNA with the growing polypeptide chain during translation.

What happens at the E-site of the ribosome?

The E-site is where the empty tRNA exits the ribosome after delivering its amino acid.