During translation, what occurs after mRNA leaves the nucleus?

• A. The mRNA attaches to the nuclear envelope for further processing.
• B. The mRNA binds to a ribosome in the cytoplasm to begin protein synthesis.
• C. The mRNA is converted into DNA by reverse transcription.
• D. The mRNA is immediately degraded by nucleases.

Answer: (B)

Verified step by step guidance

1. Understand the process of translation: Translation is the second step of gene expression, where the mRNA sequence is used to synthesize a protein. This occurs in the cytoplasm after transcription in the nucleus.
2. Recall the role of mRNA: mRNA (messenger RNA) carries the genetic code from DNA in the nucleus to the ribosomes in the cytoplasm, where protein synthesis occurs.
3. Identify the next step after mRNA leaves the nucleus: Once mRNA exits the nucleus through nuclear pores, it enters the cytoplasm and binds to a ribosome, which is the site of translation.
4. Explain the function of ribosomes: Ribosomes are molecular machines that facilitate the decoding of mRNA into a polypeptide chain. They consist of rRNA and proteins and have binding sites for mRNA and tRNA.
5. Clarify why other options are incorrect: The mRNA does not attach to the nuclear envelope for further processing, as processing occurs in the nucleus before export. It is not converted into DNA by reverse transcription, as this is not part of normal cellular processes. Additionally, mRNA is not immediately degraded by nucleases; it is used for translation before eventual degradation.