9. Which of the following is considered a Local Histone Mobilization (circle all the correct ones and explain each) a. Ejection b. Phosphorylation c. Sliding d. Methylation e. Unwrapping

Phosphorylation

Methylation

Explanation:

Histone mobilization deals with the covalent bonding of several functional groups to the free nitrogens in the R-groups of lysine in the N-terminal tail.

DNA transcription can be controlled or altered via 'methylation' on the histones. Methylation is the mode of transferring methyl group to amino group of histone proteins that form the nucleosomes, which result to chromosomes formation through wrapping of DNA double helix around it. Histones methylation can either increase or decrease genes transcription. Chromatin modification is known to stimulate neural pathways that are essential for long memories and learning.

Histones phosphorylation is associated transcriptional activation. It deals with the transfer of phosphate group to amino acids of the proteins. Phosphate group known to be negatively charged, when transferred to amino acids of the histone proteins, it creates a repulsive force with the negatively charged phosphates of the DNA backbone. It can occur in serine, tyrosine and threonine. The enzymes kinases activate phosphorylation, while protein phosphatases remove phosphate groups.