![]() Главная страница Случайная страница КАТЕГОРИИ: АвтомобилиАстрономияБиологияГеографияДом и садДругие языкиДругоеИнформатикаИсторияКультураЛитератураЛогикаМатематикаМедицинаМеталлургияМеханикаОбразованиеОхрана трудаПедагогикаПолитикаПравоПсихологияРелигияРиторикаСоциологияСпортСтроительствоТехнологияТуризмФизикаФилософияФинансыХимияЧерчениеЭкологияЭкономикаЭлектроника |
The SRY gene
The SRY gene codes for a protein called testis determining factor.This switches on other genes, causing the embryo to develop male structures. The testes develop and androgens (hormones which promote the development of male sexual organs and secondary sexual characteristics) are secreted. At about 16 weeks, an embryo with the SRY gene begins to produce immature sperm. In addition to stimulating male structures to grow, SRY suppresses the development of female structures by activating a gene on chromosome 19. This activation leads to the production of a protein called Mullerian- inhibiting substance, which destroys female structures early in their development. Lack of testis determining factor results in the development of female genital organs. Therefore, all embryos are female unless active testis determining factor makes them male.
|