Histone and epigenetic regulation

Acetylation:

The addition of acetyl groups to histone tails. This typically loosens the interaction between histones and DNA, making the chromatin more open and promoting gene expression.

Methylation:

The addition of methyl groups to histones. Depending on which amino acids are methylated and how many methyl groups are added, this modification can either activate or repress gene transcription.

Specialized Histones (Histone Variants):

These are alternative versions of standard histones that can be incorporated into nucleosomes. They often have specific roles in regulating gene expression, DNA repair, or chromatin structure.

Genomic Imprinting:

A form of monoallelic expression where only one allele of a gene is expressed depending on its parent of origin. Epigenetic marks, such as DNA methylation, silence the other allele, leading to parent-specific gene expression.

Antibody Diversity:

immune cells, somatic rearrangement refers to the process by which segments of immunoglobulin genes are shuffled to create a vast repertoire of antibodies. This rearrangement allows B cells to produce antibodies that can recognize many different antigens.

X-Inactivation:

In females, one of the two X chromosomes is randomly inactivated in each cell to balance gene dosage with males. The inactivated X chromosome condenses into a structure known as a Barr body.

Other Instances (e.g., Imprinting):

Beyond X-inactivation, some genes are subject to random allelic silencing where only one allele is expressed, contributing to variability in gene expression.

CpG sites DNA Methylation Hotspots:

CpG sites are regions where a cytosine nucleotide is followed by a guanine nucleotide. These sites are frequently methylated, which can lead to gene silencing when present in gene promoters.

BMR Relevance:

Basal metabolic rate (BMR) is the energy expended by an organism at rest. Genetic factors influence BMR by regulating metabolic pathways, affecting how efficiently energy is produced and used.

Writers:

Enzymes that add epigenetic marks (such as histone acetyltransferases and DNA methyltransferases) to DNA or histone proteins.

Erasers:

Enzymes that remove these marks (for example, histone deacetylases and demethylases), allowing changes in chromatin structure and gene expression.

Reading

Readers:

Proteins that recognize and bind to the added epigenetic marks, interpreting these signals to bring about changes in gene activity.