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.
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. This may be signaled by higher levels of FSH. High levels of FSH in women is a signal of poor ovarian function, polycystic ovary syndrome or can indicate that menopause has begun or is currently taking place.