Chromosomes and chromatin Transitional Reasoning Download PDF

Questions

1. 1.

   A molecular genetics team examines two distinct chromatin segments, designated Region 1 and Region 2, from interphase eukaryotic nuclei. Laboratory assays indicate that Region 1 exhibits low nucleosome packing density, high sensitivity to endonuclease cleavage, and substantial RNA polymerase binding. Conversely, Region 2 features tightly clustered nucleosomal arrays stabilized by linker histones that restrict endonuclease cleavage and enzyme binding. Based on these observations, which conclusion accurately explains the relationship between chromatin structure and cellular activity in these segments?

   • A) Region 2 represents euchromatin, which actively replicates and transcribes genetic information throughout interphase.
   • B) Region 1 consists of completely unfolded naked DNA that entirely lacks core histone octamers.
   • C) Region 1 represents euchromatin with accessible DNA allowing active gene expression, whereas Region 2 represents heterochromatin where dense packing represses transcription.
   • D) Region 2 facilitates accelerated transcription because tightly compacted nucleosomes concentrate transcription factors onto promoter sequences.