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 FSH levels during the follicular and luteal phase should range between 5 and 20 IU/L (international units per liter). Right before ovulation during the mid-cycle peak, FSH levels should be between 30 and 50 IU/L. If a woman is post-menopausal, her FSH levels will be naturally higher, at 60 IU/L or more. At about the age of 40, most women begin a new phase of life and hormone changes begin to take place in preparation for menopause. The ovaries begin to lose their ability to produce mature follicles, estrogen and progesterone.