Today we are learning sex-linked traits The sex-linked traits. You can find them here!

Sex Chromosomes Key Point #1 – Sex (gender) chromosomes determine if you are male or female XX = female XY = male

Sex Linked Traits Key Point #2: MOST Sex linked traits are found on the X chromosome only (in college bio you may look at some Y linked traits, but not in here!) The Y chromosomes is too small to carry the information I think that it is true that diseases can be on the Y chrosmoes, but they are very very rare and would never show up on the EOC or GEE, so I think that we should stick with saying that the Y chromosomes doesn’t really have any informaiton on it. 5

Sex Linked Traits Key Point #3 Women need two X chromosomes with a bad gene to have a sex-linked trait Men only need one X chromosomes with a bad gene to have a sex-linked trait I say bad because most sex-linked traits are diseases (sorry boys!)  but not ALL!

Sex-linked recessive traits! We are doing doing X-linked recessive traits XH = dominant Healthy Xh = recessive sick Y = neither (does not carry any h’s)

TO DO PS problems, we need to know genotypes and phenotypes! H=healthy h=sick What are carriers? -carries a copy of the Recessive allele Do you see any male carriers? Phenotype Genotype Healthy female XHXH Carrier female XHXh Sick female XhXh Healthy boy XHY Sick boy XhY

GP 1 Healthy or Sick? Healthy is dominant 1. XH Xh 2. Xh Y 3. XH Y

This next example is for…. HEMOPHELIA a disease where your blood doesn’t clot

GP-2 XH=healthy Xh=hemophilia Carrier female + healthy man! XH XH Y Xh What % of the children are girls? What % will be boys? What % will have hemophilia? What % of kids will be healthy? XH Y XH Xh XHXH XHY XH Xh XhY

GP-3 What makes something sex-linked rather than just a regular trait?

GP-4 Are males or females more susceptible (likely to be affected) to sex-linked diseases?

GP-5 Healthy female + sick man! XH Xh Y XHXh XHY XH Xh XHY What % of the children are girls? What % will be boys? What % of the kids will have hemophilia? What % of kids will be healthy? Xh Y XH XHXh XHY XH Xh XHY

GP-6 Carrier female + sick man! XH Xh Y XHXh XHY Xh Xh XhY Xh What % of the children are girls? What % will be boys? What % of the kids will have hemophilia? What % of kids will be healthy? Xh Y XH Xh XHXh XHY Xh Xh XhY

Who are the parents?!?!

Scenario 1 Katie is a carrier for alopecia (baldness). Her baby is not growing any hair at all. She is not sure if Richard, her husband, or Adam, her husband’s best friend, is the father… Richard’s genotype is XhY Adam’s genotype is XHY

XHXH XHY XHXh XhY XhXh XhY Adam Richard XH Y Xh Y XHXh XH XH Katie Xh

Scenario 2 Samantha has hemophilia blood and so does her baby. She is not sure whether Nick or Ron is the father of her baby…. Nick is a hemophiliac Ron is not Which one is the father? Use Punnett Squares to prove it. 19

WE DON’T KNOW! Either can be the father! Nick Ron Xh Y XH Y XhXh XhY XHXh XhY Xh Xh Sam XhXh XhY XHXh XhY Xh Xh

Scenario 3 Jackson is color-blind (a sex-linked trait). His mother is not a carrier for this trait but his father is incapable of differentiating between red and blue. What does this mean?! (Prove your answer with a Punnett Square!)

JACKSON IS ADOPTED XH XH XH Xh XH Xh Xh Jackson is XhY Y XH Y XH Y

What goes in my folder? Quiz Last night’s homework Worksheet Exit slip Reminders: DOLL HAIR!

Practice