April 16, 2022, 7:13 a.m. by frozenfry
A Rapid Introduction to Molecular Biology
Figure 1. A 1900 drawing of onion cells at different stages of mitosis by Edmund Wilson.Making up all living material, the cell is considered the building block of life. The nucleus, a component of most eukaryotic (nonbacterial) cells, has been known to be the hub of cellular activity for 150 years. Seen under a light [microscope][1], the nucleus appears to simply be a darker region of the cell, but as we increase magnification, we find a hodgepodge of substances in the nucleus, which undergoes a flurry of activity leading up to and during mitosis, or cell division; see Figure 1.
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A string is simply an ordered collection of symbols selected from some alphabet and formed into a word; the length of a string is the number of symbols that it contains.
An example of an DNA string (whose alphabet contains the symbols A, C, G, and T) is ATGCTTCAGAAAGGTCTTACG.
Given: A DNA string
Return: Four integers corresponding to the number of times that the symbols A, C, G, and T occur in
AGCTTTTCATTCTGACTGCAACGGGCAATATGTCTCTGTGTGGATTAAAAAAAGAGTGTCTGATAGCAGC
20 12 17 21
