Final answer:
Facultative heterochromatin is transcriptionally inactive when condensed and can be converted into euchromatin, while not always condensed during interphase and does not typically contain highly repetitive DNA sequences.
Step-by-step explanation:
Facultative heterochromatin is a dynamic and versatile form of chromatin that can switch between a condensed and less condensed state, impacting gene expression within the genome. Among the given statements, options 2 and 3 accurately describe features associated with facultative heterochromatin.
Option 2 states that facultative heterochromatin is transcriptionally inactive when condensed during interphase. This aligns with the characteristic behavior of facultative heterochromatin, where its condensed state correlates with transcriptional repression. During interphase, when the cell is not actively dividing, certain regions of the genome undergo condensation, leading to reduced gene expression. This is particularly true for facultative heterochromatin, where genes are often temporarily silenced.
Option 3 correctly notes that facultative heterochromatin has the capability to be converted into euchromatin, a more open and transcriptionally active form of chromatin. This ability to undergo a structural shift reflects the dynamic nature of facultative heterochromatin, allowing genes within these regions to become active or repressed based on cellular requirements.
However, option 1, stating that facultative heterochromatin is always condensed during interphase, is inaccurate. Facultative heterochromatin can transition between condensed and less condensed states, and its level of compaction is subject to regulatory mechanisms and cellular needs.
Option 4, indicating that facultative heterochromatin characteristically contains highly repetitive DNA sequences, is not accurate. This feature is more typical of constitutive heterochromatin, which consists of permanently condensed regions containing repetitive DNA sequences like centromeres and telomeres.
In summary, facultative heterochromatin is a flexible and regulatory component of the genome, and options 2 and 3 appropriately capture its dynamic nature and functional characteristics.