Question

How would eukaryotic genes that do not have operons ensure simultaneous expression of different genes?

This is for my assignment can you please explain in a simple way, and can you please advise me some readings about this so I can further read on it. Thank you so much.

Answer 1

NOTE: Expression of gene in eukaryotes require General transcription factor and the efficient association of these transcription factor to gene occur through chromatin Remodeling. Thus study of chromatin Remodeling and epigenetic modification could be helpful to understand how simultaneous gene expressed in eukaryotes

The associated DNA and histone proteins are collectively called chromatin; the complex is tightly bonded by attraction of the negatively charged DNA to the positively charged histones. Chromatin structure contributes to the varying levels of complexity in gene regulation. It allows simultaneous regulation of functionally or structurally related genes that tend to be present in widely spaced clusters or domains on eukaryotic DNA. Interactions of chromatin with activators and repressors can result in domains of chromatin that are open, closed, or poised for activation. Chromatin domains have various sizes and different extents of stability. These variations allow for phenomena found solely in eukaryotes, such as transcription at various stages of development and epigenetic memory throughout cell division cycles. They also allow for the maintenance of differentiated cellular states, which is crucial to the survival of multicellular organisms.

Gene expression is regulated primarily at the transcriptional level While it is also regulated at many levels (epigenetic, transcriptional, post-transcriptional, translational, and post-translational). An overall increase in the surface area of chromatin may facilitate global gene transcription due to an improved access of transcription factors to DNA. In comparison, increasing the average mass-density (i.e. increasing the macromolecular volume fraction within the nucleus) may slow diffusion and increase the non-specific binding of transcription factors to DNA.Chromatin structure and nucleosome positioning are closely associated with DNA methylation in gene regulation, and both display alterations in human cancers.Chromatin structure is largely determined by posttranslational modifications of specific amino acids on histone N-terminal tails, by which histone methyltransferases (HMTs), histone acetyltransferases (HATs), histone phosphorylases, and other enzymes catalyze the recognition (readers), addition (writers), and removal (erasers) of these functional groups, thereby influencing chromatin structure, and ultimately, gene activity potential.Chromatin modifications also delineate between genes that: (i) display inducible or tissue-specific expression profiles, (ii) display constitutive expression, and (iii) are not expressed. For instance, histone lysine mono methylation (H3K4, H3K9, H3K27, H3K79, and H4K20) and acetylation (H3K9Ac, H3K14Ac, and H3K27Ac) are correlated with gene activation. Other marks associated with gene activation include histone H3 lysine 4 tri-methylation (H3K4me3), H3K36me3, and H3K79me2. Repressed regions of the genome are enriched for H3K9me2, H3K9me3, H3K27me2, and H3K27me3 marks