When DNA is compacted by histones into 10-nm and 30-nm fibers, the DNA is unable

Question

When DNA is compacted by histones into 10-nm and 30-nm fibers, the DNA is unable to interact with proteins required for gene expression. Therefore, to allow for these proteins to act, the chromatin must constantly alter its structure. Which processes contribute to this dynamic activity? DNA supercoiling at or around H_1 methylation and phosphorylation of histone tails hydrolysis of DNA molecules where they are wrapped the nucleosome core All of the above One of the characteristics of retrotransposons is that they code for an enzyme that synthesizes DNA using an RNA template. they air found only in animal cells. they generally move by a cut-and-paste mechanism. but don't duplicate. genes are found only in Drosophila and other arthropods. encode transcription factors that control the expression of genes responsible for specific anatomical structures. are responsible for patterning during plant development in positive control of several sugar-metabolism-related operons, the catabolite activator protein (CAP) binds to DNA to stimulate transcription. What causes an increase tn activated CAP? increase in glucose and increase in cAMP decrease in glucose and increase in cAMP increase in glucose and decrease in cAMP the tryptophan operon is a repressible operon that is permanently turned on. turned on only when tryptophan is present in the growth medium. turned off only when glucose is present in the growth medium. turned off whenever tryptophan is added to the growth medium. Which of the following is characteristic of the lytic cycle? Many bacterial cells containing viral DNA are produced. Viral DNA is incorporated into the host genome. The viral genome replicates without destroying the host. A large number of phages are released at a time. The virus-host relationship usually lasts for generations.

Explanation / Answer

32. B. Methylation and phosphorylation of histone tails

33. A. Code for an enzyme that synthesizes DNA using an RNA template (reterotransposons are similar to retroviruses having reverse transcription genes)

34 .B. encode transcription factors that control the expression of henes responsible for specific-anatomical features (during early embryonic development of an organism)

35. B. Decrease in glucose and increase in cAMP

36. D. turned off when tryptophan is added to the growth medium (as bacteria no longer need to synthesize it, transcription is switched off)

37. D. A large number of phages are released at a time ( causes lysis of the cell).

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