Final answer:
Histones, DNA methylation, and microRNAs are involved in pre-transcriptional gene regulation, affecting how genes are expressed prior to transcription. Alternative splicing is a post-transcriptional process that generates multiple protein isoforms from a single gene.
Step-by-step explanation:
In the context of gene regulation, histones, DNA methylation, and microRNA are all involved in pre-transcriptional control, while alternative splicing is a post-transcriptional process. Histones are proteins around which DNA is wrapped, forming a structure called nucleosomes. The modification of histones influences how tightly DNA is wound, thereby regulating gene expression. DNA methylation is an epigenetic mechanism that can suppress gene expression by adding methyl groups to the DNA, often leading to a condensed chromosomal structure that inhibits transcription. MicroRNAs are short RNA molecules that can bind to messenger RNA (mRNA) to regulate its stability and translation, although their primary functions are post-transcriptional.
On the other hand, alternative splicing is a mechanism that occurs after transcription and involves the removal of introns and the joining of exons in the pre-mRNA to form mature mRNA transcripts. This process allows for the production of different proteins from the same gene by including or excluding certain exons.