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TOPIC: MY GOAL: GET ON TSSK. ISN p.152 MT 16, The Genetics of Life. Thurs 02.21.13. I will review DiHybrid Crosses & then learn Sex-Linked Crosses Turn to your DiHybrid Cross HW…. Bottom of ISN p. 152 – Work it!. T T P p x T t P P. Genotype Phenotype. TP. Tp. TP. Tp.
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TOPIC: MY GOAL: GET ON TSSK ISN p.152 MT 16, The Genetics of Life Thurs 02.21.13 Iwill review DiHybrid Crosses & then learn Sex-Linked Crosses Turn to your DiHybrid Cross HW…
Bottom of ISN p. 152 – Work it! T T P px T t P P Genotype Phenotype TP Tp TP Tp TTPP=4 TTPp=4 TtPP=4 TtPp=4 TP TP tP tP Tall, Purple = 16
DiHybrid Cross TOP of ISN p. 152 – Work it! T T P p x T T P P Tp TP TP Tp Genotype Phenotype TP TP TP TP TTPP=8 TtPp=8 Tall, Purple = 16
Your 2nd Job TodayISN page155 WRITE in ANSWERS • X or Y • X or Y, X • XY, XX • You will use the ‘key’ provided to work the Sex Linked Punnett Square on ISN p.154 after I explain…
Sex Xsomes = • Xsome pair #23 • XX = F • XY = M • Autosomes = • Xsome pairs #1-22 Notes, ISN p.155 AutosomesvsSex Chromosomes Amniocentesis
MALES determine the sex of the offspring! 46 Chromosomes total in humans! 2are sex xsomes: XXorXY Eggs = XorX sperm-XorY X X Y Sperm determines sex of the offspring X GIRL BOY
Traits found ONLY on the Sex Xsomes specifically the X EXAMPLES: Colorblindness… Hemophilia… Muscular Dystrophy… Traits found on Autosomes– the first 22 pair - are written as letters like Dd or FF (dimples & freckles) But when a trait is on the Sex Xsome, you change the way you write the gene… Sex Linked Traits
How do you represent Sex-Linked genes? X X c C C X Y • As a superscript: • The genes are attached or LINKED to the X sex chromosomes! That’s why they are written as superscripts. No disorders are linked to the ‘Y’ xsomes because it is so small
X X or X Xor X X Notes ISN page 155 What is a “Carrier”? Why are they “normal”? Carrier = only F = do NOT exhibit trait, just carry it & MIGHT pass it on c C XYorXY c C C C c c So why can’t men be carriers AND why do more men have Sex-Linked Genetic Disorders???? c c c X X X Y
Sex Linked Punnett Square Cross a Heterozygous Normal Color Vision Femalewith a colorblind male. XCXcx XcY
XCXcxXcY Genotype Phenotype XCXc XCXc= 1 F, Carrier = 25% XC Xc Xc Xc XcXc= 1 XcY F, CB = 25% XCY= 1 M, Normal = 25% Xc Y XcY= XC Y 1 M, CB = 25% ?
Your 3rd Job TodayISN page154 WORK the 2 Sex Linked Punnett Squares 1st = Color Vision 2nd = Hemophilia Use the Keys on ISN p.155
XcYxXCXC Genotype Phenotype XcY XC Xc= Carrier are NORMAL! = 50% 2 XC Xc XC Y XC XC Y= 2 M, normal vision = 50% XC Xc XC Y XC % children w/ normal vision??? 100%
XhXhx XHY Genotype Phenotype XH Y XH Xh= 2 Carrier = 50% Xh Xh XH Xh Xh Y XhY= 2 M, hemophilia = 50% Xh Y 50/50 chance children will be normal XH Xh
Study a bit each night.. HOMEWORK Be the change you wish to see in the world