Question

why is mrna necessary in eukaryotic cells? so that ribosomes can enter the nucleus because rna cant leave the nucleus because dna cant leave the nucleus so that dna can enter the nucleus

Explanation:

In eukaryotic cells, DNA is located in the nucleus. Ribosomes, which are involved in protein synthesis, are in the cytoplasm. mRNA (messenger RNA) is transcribed from DNA in the nucleus. Then, mRNA can leave the nucleus and carry the genetic information (copied from DNA) to the ribosomes in the cytoplasm. This is because DNA itself cannot leave the nucleus. Ribosomes do not enter the nucleus for protein - synthesis - related processes. RNA (including mRNA) can leave the nucleus. DNA is already in the nucleus and does not need to enter it again for the process of using its information for protein synthesis.

Answer:

Because DNA can't leave the nucleus