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Who was Morgan and what did he do?? http://www.columbia.edu/cu/alumni/Magazine/Legacies/Morgan/ 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 F1 Generation Conclusion P Generation X X w w All offspring had red eyes. w Eggs Results F2 Generation X Y F1 Generation w Sperm w w w w Eggs F2 Generation w w Sperm w w w w w w © 2014 Pearson Education, Inc. w 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 X chromosomes Early embryo: Two cell populations in adult cat: Allele for black fur Cell division and X chromosome inactivation Active X Inactive X Active X Black fur © 2014 Pearson Education, Inc. Allele for orange fur Orange fur https://smartsite.ucdavis.edu/access/content/user/000029 50/bis10v/media/ch10/x_inactivation.html © 2014 Pearson Education, Inc. Anhydrotic dysplasia X = normal sweat glands XY….would be? Normal male X’Y…would be? No sweat glands male X-linked sweat gland problem X' = absence of sweat glands. 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) Double mutant (black body, vestigial wings) b vg+ b vg b vg+ b vg Term! Wild-type F1 dihybrid (gray body, normal wings) b vg+ b vg © 2014 Pearson Education, Inc. Figure 12.10b F1 dihybrid testcross Wild-type F1 dihybrid (gray body, normal wings) b vg+ b vg b vg Gametes?? Meiosis I b vg b vg+ b vg b vg+ b vg b vg b vg b vg b vg Homozygous recessive (black body, vestigial wings) b vg+ How many different kindsMeiosis of gametes I and II from male? b vg b vg How many different gametes from female? Meiosis If IIno Eggs b+ vg+ Recombinant chromosomes recombination? b vg b vg b+ vg With recombination? © 2014 Pearson Education, Inc. b vg+ b vg Sperm Figure 12.10c Recombinant chromosomes b vg+ b vg b vg 944 Blackvestigial 206 Grayvestigial b vg Eggs Testcross offspring 965 Wild type (gray-normal) 185 Blacknormal b vg b vg b vg b vg b vg b vg b vg b vg Parental-type offspring Recombinant offspring Recombination 391 recombinants 100 17% frequency 2,300 total offspring © 2014 Pearson Education, Inc. b vg Sperm Figure 12.12 Mutant phenotypes Short aristae 0 Long aristae (appendages on head) Black body Cinnabar eyes 48.5 57.5 Gray body Red eyes Vestigial wings 67.0 Normal wings Wild-type phenotypes © 2014 Pearson Education, Inc. Brown eyes 104.5 Red eyes 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. © 2014 Pearson Education, Inc.