The second carbon is connected to the amino group. Amino means there is an NH 2 group bonded to the carbon atom. In the image, you see a + and a -. Those positive and negative signs are there because, in amino acids, one hydrogen atom moves to the other end of the molecule. An extra H gives you a positive charge.
Ranges of normal estrogen levels are measured in parts pg/ml of estradiol. In normal reproductive age women, during the menstrual cycle, estradiol levels range from 50-400 pg/ml. The actual normal level of estrogen varies during different parts of the menstrual cycle. In menopause, the general range may be 10-20 pg/ml.
For menstruating women, the normal values for FSH blood test, is 4.7 mlU/ml to 21.5 mlU/ml, while for post-menopausal women, it is 25.8 mIU/ml to 134.8 mIU/ml. If the level is higher than 25, then the woman may be in the peri or premenopausal stage, while she is approaching menopause, if the level is around 50. However, the normal range for FSH can vary from lab to lab, which should be considered while evaluating the results of the test.