Ans.
Chromatin molecules are made up of DNA and histone proteins. Modification of chromatin structure include covalent, post-translational changes in histone proteins, present in chromation. Acetylation and methylation are two important histone modifications that affect structure of chromatin molecules.
Acetylation involves addition of an acetyl group to histones that increases transcription of DNA by loosen the association between DNA and nucleosome.
Methylation involves addition of a methyl group to histones that results in condensation of chromatin molecule and thus, decreases transcription of DNA.
Both acetylation and methylation are reversible processes.
Many chromatin modifications are genetic, means they can pass from one generation to another generation, called epigenetic modifications.
Thus, options B), C), D), E), and F).
The correct option is THE ELECTRON IN THE OUTERMOST ELECTRON SHELL.
Different levels of energy exist in the atom of an element and these levels are filled with electrons. The electrons in the innermost shell has the lowest energy level while the electrons in the outermost shell has the highest energy level. For an electron to increase its energy level, it has to move to an higher shell; and to decrease its energy level it has to move to a lower shell.
Most adult stem cells come from the bone marrow.
Answer:
A blizzard can form when warm air combines with a high pressure system.
Explanation:
A high pressure zone is defined by cold air mass that has higher density than surrounding air mass. Therefore when a warm air current blows towards the high pressure system, the warm air mass rises over the cold air mass of the high pressure system.
The warm air begins to cool at the front between the cold air mass and warm air mass. Usually for a blizzard to occur the cold air mass is usually below freezing point temperatures. Therefore the moisture in the warm air cools and freezes into snowflakes. This is why the winds of a blizzard are accompanied by snowflakes akin to a winter storm.
Lean More:
For more on blizzards check out;
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