Turn in your Karyotype worksheets from last class in INBOX! Today’s Warm Up – Genetics: Punnett Squares and Incomplete vs Codominance worksheet (by inbox)

Ratio Example Genotypic Ratio ___ : ___ : ___ Phenotypic Ratio ___ : ___ (YY)(Yy)(yy) (Yellow)(Green)

Turner’s Syndrome

Down Syndrome

None! It’s a normal Male

Klinefelter’s Syndrome

Complex Inheritance – Sex Linked Pg. ___

Today’s Learning Target  I understand the inheritance of sex-linked traits  I can explain how colorblindness is connected to the sex chromosomes of a human.

Sex-Linked

Sex-Linked Inheritance A. Sex-Linked traits are only carried on the X chromosome Pg. 69

Sex-Linked Inheritance B. Males have only one X chromosome, so they are more likely to inherit a sex linked trait. 1. Examples in humans: colorblindness and hemophilia XY - Male Pg. 69

Sex-Linked Inheritance C. Writing a genotype for sex linked 1. Must include sex chromosomes 2. Use subscripts to denote the allele ex: X H X h Pg. 69

13 Sex-linked Traits Sex Chromosomes XX chromosome - femaleXY chromosome - male fruit fly eye color Example: Eye color in fruit flies. Red eyes are dominant to white eyes.

Sex-Linked Inheritance Female Male Red eyes White eyes Carrier *Sex Linked Traits occur more in males than females (males cannot be carriers) XRXrXRXr XrXrXrXr XRXrXRXr XRYXRY XrYXrY

X G Y X g Y X g X G X g X G

Sex-Linked Inheritance D. Using a Punnett Square for sex linked 1. Cross both the sex chromosomes and the allele Pg. 69

18 Sex-linked Trait Problem Example: Eye color in fruit flies (red-eyed male) x (white-eyed female) ? ? Remember: the Y chromosome in males does not carry traits. RR = red eyed Rr = red eyed rr = white eyed XY = male XX = female XRXR XrXr XrXr Y X R Y xX r X r

19 Sex-linked Trait Solution: X R X r X r Y X R X r X r Y 50% red eyed female white eyed 50% white eyed male XRXR XrXr XrXr Y Phenotypes:

Colorblindness Test On the next slide, silently read the numbers that are written in each picture. Make a note of the numbers that you can see. If you cannot see a number, do not write down anything.

EVERYONE SEES 12 EVEN COLOR BLIND PEOPLE NORMAL SEES 2 COLOR BLIND SEES NOTHING NORMAL SEES 8 COLOR BLIND SEES NOTHING NORMAL SEES 29 COLOR BLIND MAY SEE SOMETHING NORMAL SEES 45 COLOR BLIND SEES NOTHING NORMAL SEES 5 COLOR BLIND SEES NOTHING NORMAL SEES 6 COLOR BLIND SEES NOTHING EVERYONE SEES 56 EVEN COLOR BLIND PEOPLE NORMAL SEES 7 COLOR BLIND SEES NOTHING

Colorblindness Inheritance

Sex-Linked in Humans D. Colorblindness – difficulty distinguishing similar colors C = normalc = colorblind Cross Female Carrier with Normal Male X C YXC XcXC Xc

Sex-Linked in Humans Cross colorblind female with normal vision male Key: Parent 1: Parent 2:

Sex-Linked in Humans All Normal Females 50% Normal Males

Could parents with normal vision have a daughter with colorblindness?

29 Female Carriers

Hemophilia Sex-linked disorder Protein needed for blood clotting is missing, people can bleed to death from minor cuts 1 in 10,000 males is born with a form of hemophilia Can be treated by injection of normal clotting proteins

Sex-Linked in Humans E. Hemophilia – blood doesn’t clot properly Normal HeterozygousMale with FemaleHemophilia Xh YXh YXH XhXH Xh

Hemophilia Sex-linked disorder Protein needed for blood clotting is missing, people can bleed to death from minor cuts 1 in 10,000 males is born with a form of hemophilia Can be treated by injection of normal clotting proteins

Sex-Linked in Humans ½ Offspring has hemophilia

37 Sex-linked Trait Problem Example: Eye color in fruit flies (red-eyed male) x (white-eyed female) ? ? Remember: the Y chromosome in males does not carry traits. RR = red eyed Rr = red eyed rr = white eyed XY = male XX = female XRXR XrXr XrXr Y X R Y xX r X r

38 Sex-linked Trait Solution: X R X r X r Y X R X r X r Y 50% red eyed female white eyed 50% white eyed male XRXR XrXr XrXr Y Phenotypes:

X G XgYXgY X G X g XGXgXGXg XGYXGYXGYXGY

X g XGYXGY

yes no 2:2

Show the percentages for each 1.Cross a heterozygous female with a colorblind male. 2. Cross a colorblind female with a normal vision male. 3. Cross a heterozygous red eyed fly with a red eyed male.