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20-Oct-2017 00:43

Sex determination in humans occurs at the time of conception.It is the process of the development of sex differences between males and females.We published earlier Lisa ann fucked in the ass without mercy in the hospital ! recommend that you watch the video titled.bangbors com. www male remale shemale xxx photos videos free download com. download free mobile video of porn sex between male or female. ' Determining whether a baby will become a boy or a girl is all about the sex chromosomes the baby inherits from mom and dad.In this lesson, we will discuss how sex is determined, what X-inactivation means and what Barr bodies are.

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Normally, each person has two sex chromosomes; one is passed down from mom and the other from dad.

A woman has two X chromosomes and a male has an X and a Y chromosome. So, in humans, sex determination is determined by dad. Females receive two X chromosomes, whereas males receive only one chromosome. If the X-linked genes were expressed equally in both sexes, females would produce approximately twice the level of X-linked gene products as would males.

When a pregnancy occurs, the baby always inherits an X from mom, but it is up to dad whether the second chromosome will be another X or a Y. This difference would disturb metabolic balance in one sex or the other.

X-inactivation is the process of bringing equivalence in the expression of X-linked genes in females and males.This anticipation only heightens as mom's baby bump continues to grow.