Which of the following characteristics is similar for spermatogenesis and oogenesis?
a. Age at which meiosis begins
b. Amount of cytoplasm retained
c. DNA replication during meiosis
d. Length of prophase I
The Correct option is C
Explanation with High Yield Facts:
The actual process of manipulation of DNA and chromosomes during meiosis is very similar in spermatogenesis and oogenesis. However, the processes also differ in many other respects: In oogenesis, the process of meiosis begins before birth, and arrests between birth and puberty in prophase I. In contrast, spermatogenesis does not begin until puberty (see choice A). The egg retains a large volume of cytoplasm (choice B), while nearly all the cytoplasm is stripped during formation of a sperm. As noted above, in oogenesis, meiosis is arrested in prophase I, which is consequently very prolonged in the female. In spermatogenesis, meiosis is completed in a much shorter time (choice D).
NOTE: Both the egg and the sperm have mitochondria, but those of the sperm are left outside when the sperm nucleus enters the egg, and consequently do not contribute to the mitochondrial genome of the fetus. Instead, the mitochondria are transmitted from the egg to the fetus. Traits coded for by mitochondrial DNA are therefore inherited in a matrilineal fashion.
0 comments:
Post a Comment