Final answer:
Heterochromatin in eukaryotic cells prevents transcription, DNA replication, (option 2) viral proliferation, and transposable element movement due to its tightly packed structure. However, translation is not directly affected as it occurs outside the nucleus in the cytoplasm.
Step-by-step explanation:
In eukaryotic cells, heterochromatin primarily prevents transcription. Heterochromatin is tightly packed DNA , which makes it inaccessible to transcription factors and the transcription machinery. As a result, the genes in these regions are not typically expressed. Heterochromatin also plays a role in other cellular processes, such as impeding DNA replication, transposable element movement, and viral proliferation, because the tightly packed structure poses a barrier to enzymes and other factors needed for these processes. Although not directly prevented by heterochromatin, translation occurs outside the nucleus and therefore is not directly affected by the state of chromatin within the nucleus.
Within this context, heterochromatin also contributes to the regulation of gene expression by affecting accessibility to the underlying DNA for necessary transcriptional machinery. DNA replication can also be affected, as the replication machinery must contend with the tightly packed heterochromatin. Furthermore, viral proliferation is often hindered because viruses require access to the host cell's chromatin to integrate their genetic material and replicate. Finally, the movement of transposable elements, which are DNA sequences that can change their position within the genome, is often limited in regions of heterochromatin because they cannot easily access the tightly packed DNA for transposition.