2. AP Biology Sex Linked Traits

3. AP Biology Sex linked traits  Genes are on sex chromosomes (pair 23)  as opposed to autosomal chromosomes

4. AP Biology Genes on sex chromosomes  Y chromosome  few genes other than SRY  SRY - Sex-determining Region of Y  turns on genes for production of male hormones  X chromosome  other genes/traits beyond sex determination

5. AP Biology RRrr You would think this right? x rr R R Rr 100% red eyes Rr x Rr R r RR Rrrr Rr 3 red : 1 white Doesn’t work that way!

6. AP Biology XRXRXRXR XrYXrY But it’s not normal dominance…its sex- linked x XrXr Y XRXR 100% red eyes XRXR XRXrXRXr XRYXRY XRYXRYXRXrXRXr x XRXrXRXr XRYXRY XRXR Y XRXR XrXr XRXrXRXr XRYXRYXRXRXRXR XrYXrY 100% red females 50% red males; 50% white males

7. AP Biology Hemophilia Hh x HH XHYXHY XHXhXHXh XHXhXHXh XHXH XhXh XHYXHY Y XHXH sex-linked recessive XHXH Y male / sperm XHXH XhXh female / eggs XHXHXHXH XHXhXHXh XHYXHYXhYXhY XHXHXHXH XHYXHY XHXhXHXh XhYXhY carrierdisease

8. AP Biology Colorblindness Hh x HH XHYXHY XHXhXHXh sex-linked recessive XHXH Y male / sperm XHXH XhXh female / eggs XHXHXHXH XHXhXHXh XHYXHYXhYXhY XHXHXHXH XHYXHY XHXhXHXh XhYXhY carrierdisease

9. AP Biology What about Baldness? Great!!!! Any Questions?