Explanation : Female is carrier of colorblindness and the male with whom se bears a child is normal .
Now, we know colourblindness is a 'x' linked disease.
Female will produce two gametes one for normal 'x' and other 'x' which is carrier for recessive trait.
And male will produce one 'x' and one 'y' gamete.
Here 50% individual will be female who may or may not be carrier but can never be affected or colorblind
And among male individuals who are formed because male parent will share its 'y' chromosome has 50% chance of being colorblind. So chance of getting affected progeny is 50% of 50% i.e. 25%.
lysine residues on the histone tails of the octamer cn be activated by both acetylation and methylation patterns to influence accessibility or silencing of the genes respectiviely. for example, acetylation of H3K27 (histone 3 lysine residue 27) brings about a region of active chromatin allowing access to transcription activity while its trimethylation will cause silencing of the associated gene at that particular area (no expression of that gene)
