Histone methylation is a process by which methyl groups are transferred to amino acids of histone proteins that make up nucleosomes, which the DNA double helix wraps around to form chromosomes.he fundamental unit of chromatin, called a nucleosome, contains DNA wound around a protein octamer. This octamer consists of two copies each of four histone proteins: H2A, H2B, H3, and H4. Each one of these proteins has a tail extension, and these tails are the targets of nucleosome modification by methylation.
The definition of a prude is a very proper and modest person. An example of a prude is a person who wears a lot of clothing in the summer to cover their bodies because they don't want to show their bare skin.
Preclude is defined as  to prevent something from happening or to prevent someone from doing something. An example of preclude is when you take someone's keys away so that they cannot drive.