The following statements are about the control of chromatin condensation. Select True or False for each. T/F Reducing histone acetylase activity is likely to decrease gene transcription. T/F Mutations that reduce the number of positively charged amino acids on histones should promote open chromatin. T/F Chromatin remodeling complexes add chemical groups to histones. T/F Adding an inhibitor of DNA methylation is likely to reduce gene transcription.

Verified step by step guidance

1. T/F Reducing histone acetylase activity is likely to decrease gene transcription. - True. Histone acetylases add acetyl groups to histones, which reduces their positive charge and leads to a more open chromatin structure, facilitating gene transcription. Reducing their activity would lead to less acetylation, more condensed chromatin, and decreased transcription.
2. T/F Mutations that reduce the number of positively charged amino acids on histones should promote open chromatin. - False. Positively charged amino acids on histones help in binding with the negatively charged DNA, keeping the chromatin condensed. Reducing these charges would disrupt normal chromatin structure and function.
3. T/F Chromatin remodeling complexes add chemical groups to histones. - False. Chromatin remodeling complexes primarily function by repositioning nucleosomes and altering nucleosome density, not by adding chemical groups to histones. The addition of chemical groups to histones is mainly carried out by enzymes like histone acetyltransferases and methyltransferases.
4. T/F Adding an inhibitor of DNA methylation is likely to reduce gene transcription. - False. DNA methylation generally acts to repress gene transcription by condensing chromatin. Inhibiting DNA methylation would typically lead to less condensed chromatin and potentially increased gene transcription.

Key Concepts

Histone Acetylation

Histone acetylation is a post-translational modification where acetyl groups are added to the lysine residues of histone proteins. This modification reduces the positive charge on histones, leading to a more relaxed chromatin structure, which facilitates gene transcription. Conversely, reducing histone acetylase activity typically results in increased histone compaction and decreased gene expression.

Chromatin Structure and Charge

Histones are rich in positively charged amino acids, which interact with the negatively charged DNA, promoting tight packing of chromatin. Mutations that reduce these positively charged residues can lead to a more open chromatin configuration, allowing for greater accessibility of transcription factors and increased gene expression. Thus, the charge of histones plays a crucial role in chromatin dynamics.

Chromatin Remodeling Complexes

Chromatin remodeling complexes are multi-protein assemblies that alter the structure of chromatin, making it more or less accessible for transcription. They do not add chemical groups to histones; instead, they utilize ATP to reposition or evict nucleosomes, thereby influencing gene expression. Their activity is essential for the regulation of genes in response to various cellular signals.