I would say oxygen because respiration is breathing mechanically.
Answer:
Б. молоточком, коваделком, стремінцем
Answer:
Addition of a(n) methyl group to certain lysine residues of a histone protein makes the region of chromatin transcriptionally silent; addition of a(n) acetyl group to certain lysine residues makes the region of chromatin transcriptionally active.
Explanation:
The changes suffered in the expression and activity of the genes are studied by the Epigenetics.