Please help me with this, they want very detailed answers and its not from our t

Question

Please help me with this, they want very detailed answers and its not from our textbook so I'm lost. Thank you so much.

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Instructions: Students are required to provide detailed answers to each question. Answers should should demonstrate comprehension of the material and should not be vauge.

QUESTION #2 [8 pts] a) DNA within cells is usually wrapped around histone proteins to form a complex structure called chromatin. Describe how chromatin is important for cells during mitosis and meiosis. [2 pts] b) Chromatin structure is also important for transcriptional regulation. Explain how the structures of euchromatin and heterochromatin affect how genes are transcribed. [2 pts] c) How, then, do you suspect transcription is affected during mitosis? Explain your reasoning. [2 pts] d Aditionally, istones themselves can be involved in transciptional regulation In what two ways do histones contribute to regulation of transcription? 12 pts]

Explanation / Answer

All the cells in the body contain almost identical genome sequence (except for few immune system cells). However, all cells do not express all the genes all the time. Each tissue type expresses a specific set of genes at specific time period i.e. temporal and spatial expression. Such genes are known as tissue-specific genes. These tissue-specific genes are responsible for different structures and functions of different tissues in our body. The tissue-specific gene expression is mediated by epigenetic as well as transcriptional gene regulation.

Importance of chromatin during cell division: The chromatin condenses during cell division and forms chromosomes. This allows for efficient segregation of chromosomes during anaphase.

Importance of chromatin in transcriptional regulation: Epigenetic modifications alter the recruitment of RNA polymerase to the gene locus by changing the compactness of the chromatin. Ex: Histone modifications and DNA methylation.

Euchromatin is transcriptionally active chromatin.

Heterochromatin is transcriptionally inactive chromatin.

Effect of chromatin during mitosis on gene expression: Since genome is in compact chromatin shape during cell division, it is normally transcriptionally inactive. All the gene products required for cell division are synthesized prior to M-phase during the interphase.

Histone methylation increases the binding of histones to DNA. This leads to transcriptional silencing.

Histone acetylation decreases the binding of histones to DNA. This leads to transcriptional activation.

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