BIOLOGY 102 Lecture Notes - Lecture 12: Y Chromosome, Karyotype, Gonad
Document Summary
X and y chromosome play key role in sex determination. Y chromosome carries the sry gene: sex-determining region of the y, it stimulates testosterone production in growing fetuses. Sry and testosterone determine sex of developing embryo. Sry gene triggers embryonic gonad tissue to become testes. Testosterone binds to cell receptors causing male sexual characteristics to develop. If neither sry not testosterone present, default is female. Male and female genitalia form from same embryonic tissue. Two ways to get a mismatch between karyotype and sex. Loss or gain of sry gene: if sry non-functional, male pathway no initiated, xy female: swyer syndrome. Some (but not most) individuals have mix of masculine and feminine characteristics. Inability of cells to sense testosterone: androgen insensitivity syndrome (ais): xy females. Can result in range of phenotypes depending on severity of insensitivity. Partial androgen insensitivity can result in normal female characteristics, both male and female sex characteristics or normal male sex characteristics.
