The answer is both in males and females; only in males. Males
have one Y chromosome and one X chromosome, while females
have two X chromosomes. In mammals, the Y chromosome controls a
gene which is the SRY, which produces embryonic improvement as a male. The Y chromosomes of males and
other mammals also contain other genes needed for normal sperm production.
There is more to DNA than cytochrome c. This is just one protein.
