Question

A number of experiments have demonstrated that areas of the genome that are transcriptionally inactive are also resistant to DNase I digestion. However, transcriptionally active areas are DNase sensitive. Describe how DNase I resistance or sensitivity might indicate transcriptional activity A number of experiments have demonstrated that areas of the genome that are transcriptionally inactive are also resistant to DNase I digestion. However, transcriptionally active areas are DNase I sensitive. Describe how DNase I resistance or sensitivity might indicate transcriptional activity

a.When DNA is transcriptionally inactive, it is in a less condensed state and as such, less open to DNase digestion.
b.When DNA is transcriptionaly active, it is in a less condensed state and as such, more open to DNase digestion.
c.When DNA is transcriptionally active, it is in a more condensed state and as such, more open to DNase digestion.
d.The condensation state does not affect resistance to DNase digestion. Res stance depends on the presence of specific methylation markers.

Answer 1

Transcriptionally active DNA is less condensed and more susceptible to DNase I digestion, while inactive DNA is more condensed and resistant. Statement b is correct as it describes active DNA being less condensed and thus more accessible to DNase I.

Step-by-step explanation:

Understanding the relationship between DNase I sensitivity and transcriptional activity is crucial in genomics. Chromatin can exist in two states: euchromatin, which is less condensed and associated with transcriptionally active regions, and heterochromatin, which is highly condensed and correlates with transcriptional inactivity.

The less condensed state of euchromatin allows for the nucleosomes to slide along the DNA and expose regions for transcription factor binding. This open state makes the DNA more susceptible to enzymatic digestion by DNase I.

Conversely, DNA in heterochromatin is tightly wrapped around histones and often heavily methylated, making it inaccessible to enzymes like DNase I and transcriptionally inactive.

In summary, DNase I sensitivity indicates transcriptional activity because active regions of the genome are more open and exposed, resulting in increased enzyme accessibility. Therefore, statement b, when DNA is transcriptionally active, it is in a less condensed state and as such, more open to DNase digestion, is the correct option.