Final answer:
Histone acetylation reduces the positive charge on histones, leading to a looser DNA-histone structure, allowing transcription factors to initiate transcription and activate gene expression. This form of epigenetic regulation can influence how genes are expressed without altering the nucleotide sequence.
Step-by-step explanation:
The significance of histone acetylation in gene regulation lies in its ability to affect chromosomal structure, thereby influencing transcription. Acetyl groups are added to histones by histone acetyltransferases (HAT enzymes), which reduces the positive charge of histones and loosens the tight DNA-histone association. This more relaxed conformation allows transcription factors to access the DNA and initiate transcription, thus activating gene expression.
Conversely, when acetyl groups are removed by histone deacetylases, the chromatin structure becomes more condensed, hindering access of transcription machinery and effectively silencing gene expression. These changes in gene expression do not alter the nucleotide sequence and are part of epigenetic regulation, which can persist through multiple rounds of cell division, indicating their importance in cellular function and development.