The answer to this question would be: vitamin
Some bacteria can produce vitamin K2 in the intestine. Other bacteria also able to change vitamin K1 into vitamin K2. But the amount produced is not much, so human still need to fulfill it from the diet. Vitamin K has a role in calcium regulation and in blood clotting pathway.
Sister chromatids are two identical copies of Chromosome that is formed by the replication of a single chromosome.
This copies are formed during mitosis. Later on, these two sisters chromatids will grown into two different Cells
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