Ace the Molecular Genetics Challenge 2026 – Decode Your DNA Dream!

In male Drosophila, upregulating the single X chromosome to match female expression is achieved through the MSL complex. This complex binds to the X chromosome in male cells, aided by the roX1 and roX2 noncoding RNAs, and uses MOF, a histone acetyltransferase, to acetylate histone H4 at lysine 16 (H4K16ac). That acetylation loosens chromatin structure and boosts transcription across the X, balancing gene output with females who have two X chromosomes. The other options correspond to different regulatory roles: Polycomb group proteins generally repress transcription, the RISC complex is involved in RNA interference, and histone deacetylases remove acetyl groups to tighten chromatin and repress expression, not upregulate it.