© 2014 Pearson Education, Inc. Who was Morgan and what did he do?? Using fly notation cross a female red eyed fly with a male white eyed fly! (what do you rememeber?)

© 2014 Pearson Education, Inc. Figure 12.4 Experiment P Generation Results F 1 Generation F 2 Generation All offspring had red eyes. Eggs ww ww w w ww ww ww ww w Sperm X Y X X ww ww ww ww ww ww w Conclusion F 1 Generation F 2 Generation P Generation

© 2014 Pearson Education, Inc. EX. Calico cats (One of the genes for hair color is on X chromosome) Two alleles (orange or black) Why are females patchy?? Each patch has a different X turned on (orange or black) Orange patch=bunch of cells there with the X with the orange allele turned on. Black patch=bunch of cells with the black X on. Why are males not patchy like females? Single X and so either the orange or the black hair color gene on in entire body.

© 2014 Pearson Education, Inc. X = orange X = black MALES: XY = orange XY = black FEMALES: XX = orange X X = black X X = orange or black patches

© 2014 Pearson Education, Inc. Figure 12.8 Early embryo: Two cell populations in adult cat: X chromosomes Cell division and X chromosome inactivation Allele for orange fur Allele for black fur Active X Orange furBlack fur Inactive X Active X

© 2014 Pearson Education, Inc. 50/bis10v/media/ch10/x_inactivation.html

© 2014 Pearson Education, Inc. Anhydrotic dysplasia X-linked sweat gland problem X = normal sweat glands X' = absence of sweat glands. XY….would be? Normal male X’Y…would be? No sweat glands male XX….. Normal female X'X' do not have sweat glands XX' ….. Heterozygous females have patches of skin with sweat glands and patches of skin without sweat glands. So swaths or populations of cells that have one X turned on and other patches with a different X on.

© 2014 Pearson Education, Inc. What do you know about colorblindness? X linked Given X inactivation …….should heterozygous females for colorblindness be able to see color?

© 2014 Pearson Education, Inc. What do you know about colorblindness? Suppose: X = color vision X’ = color blind The retina of a heterozygous (XX’) female will have some cells with the X inactivated and other cells with the X’ inactivated. A heterozygous female has some color blind cells in her retina. The non-color blind cells enable her to see color.

© 2014 Pearson Education, Inc. Figure 12.10a P generation (homozygous) Wild type (gray body, normal wings) Wild-type F 1 dihybrid (gray body, normal wings) b  vg + Double mutant (black body, vestigial wings) b  vg + b vg Term!

© 2014 Pearson Education, Inc. Figure 12.10b b  vg + b vg b  vg + b vg b  vg + b  vg b vg  b vg Meiosis I Meiosis I and II Meiosis II Eggs b vg b vg + b + vgb + vg + Sperm Wild-type F 1 dihybrid (gray body, normal wings) F 1 dihybrid testcross Recombinant chromosomes Homozygous recessive (black body, vestigial wings) Gametes?? How many different kinds of gametes from male? How many different gametes from female? If no recombination? With recombination?

© 2014 Pearson Education, Inc. Figure 12.10c b  vg + b vg b vg  b  vg Recombinant chromosomes Eggs 185 Black- normal 206 Gray- vestigial 944 Black- vestigial 965 Wild type (gray-normal) Testcross offspring Sperm b vg b vg  b  vg b vg b  vg  b vg Parental-type offspring Recombinant offspring Recombination frequency   100  17% 2,300 total offspring 391 recombinants

© 2014 Pearson Education, Inc. Figure Short aristae Black body Cinnabar eyes Vestigial wings Brown eyes Red eyes Normal wings Red eyes Gray body Long aristae (appendages on head) Wild-type phenotypes Mutant phenotypes

© 2014 Pearson Education, Inc. 1. What kind of sex determination did our ancestors have and when did the y chrosome evolve? 2. What do they mean SRY evolved from a related gene?? 3. The chapter talks about SRY, what does it stand for? 4. Why do you think the Y lost its ability to recombine (other than at the tips)?? 5. Why would the Y lose genes? What kinds of genes would it be unlikely to lose and why?

© 2014 Pearson Education, Inc. 6. Chimps have lost some genes as well but there seems to be many duplicated genes on the chimp Y, what might these genes be doing? 7. To review…What is the debate about in the article? 8. What are the “dying gasps of the Y chromosome”?

© 2014 Pearson Education, Inc. Sex Determination patterns Chromosomal determination Remember…..we have autosomes as well as sex chromosomes 1.XX/XY -humans and drosophila

© 2014 Pearson Education, Inc. 2. ZW –birds reversed compared to the XY system: females are heterogametic-females have two different kinds of chromosomes (ZW) males have two of the same kind of chromosomes (ZZ) So they are…….

© 2014 Pearson Education, Inc. 3. Haplodiploidy-insect such as ants and bees Unfertilized eggs develop into haploid individuals, which are the males. Diploid individuals are generally female Males cannot have sons or fathers.

© 2014 Pearson Education, Inc. 3. Haplodiploidy-insect such as ants and bees Unfertilized eggs develop into haploid individuals, which are the males. Diploid individuals are generally female Males cannot have sons or fathers. Many females can decide the sex of their offspring by storing received sperm and either releasing it for fertilization or not. This allows them to create more workers (who are male), depending on the status of the colony

© 2014 Pearson Education, Inc. Environmental Sex Determination Temperature at which egg is incubated- alligators, turtles, sex Sometimes one sex hatches out when it is hot and the other when it is cool. Males are cool in turtles. For others, the extreme temperatures are one sex and the middle temperature is the other. Males hatch out of middle temps in alligators.