What is a base substitution?

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Base substitutions are the simplest type of gene-level mutation, and they involve the swapping of one nucleotide for another during DNA replication. For example, during replication, a thymine nucleotide might be inserted in place of a guanine nucleotide.

Base substitutions are the basic form of gene-level alteration, and they occur when one nucleotide is swapped for another during DNA replication. A thymine nucleotide, for example, might be substituted for a guanine nucleotide during replication.

the corpus luteum secretes estrogens and progesterone. the latter hormone causes changes in the uterus that make it more suitable for implantation of the fertilized ovum and the nourishment of the embryo. if the egg is not fertilized, the corpus luteum becomes inactive after 10–14 days, and menstruation occurs.

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