From what i have learned or at least i remember its true
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During the 32nd week of gestation, good luck!
Answer:
In all organisms, the instructions for specifying the characteristics of the organism are carried in DNA, a large polymer formed from subunits of four kinds (A, G, C, and T). ...
Most of the cells in a human contain two copies of each of 22 different chromosomes. ...
Changes in DNA (mutations) occur spontaneously at low rates.
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