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Lecture 9

Study Questions for Lecture 9 Study question answers to lecture 9.

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Biology (Sci)
BIOL 303
Dragana Miskovic

1What is the difference between mammalian and bird sex determination What is the similarityIn mammals the presence of the second X or Y chromosome determines whether it is a male or female In birds males ZZ and females ZW2 List and briefly explain 2 female and two male sex chromosome abnormalitiesFemale abnormalitiesTurner syndrome when a female only inherts one X chromosome the genotype is XO They are short webbed neck and sterileMetafemales are females that inherit an extra X chromosome The genotype is XXX or XXXX super females They are fertile tall and possibly slight mental retardationMale abnormalitiesKlinefelter Syndrome where males inherit extra X chromosomes their genotypes are XXY XXXY They are tall mostly sterile and have body feminizationXYY syndrome males inherit an extra Y chromosome their genotype isXYY They have high testosterone are tall fertile and have acne in puberty3Define primary and secondary sex determination in mammalsPrimary determination determination of gonadsThis is when sex determination is based on chromosome and no environment component Y carries a gene that encodes for testisdetermining factorthey organize into testis instead of ovaries No matter how many X chromosomes there are one Y chromosome results in a maleSecondary sex determination hormonal regulation of the sexual phenotypeIt is the response to hormones released by ovaries and testes There are two phases one during embryo development organogenesis and the second phase during puberty The default sex is females even without functional ovaries due to maternal influence Male requires 2 hormones AMH and testosterone4Where do the mammalian genitalia originate from remember there are two places of origin one for external and one for internal genitaliaIn males Wnt signals in genital tubercle activates male development In females Wnt signals in the genital ridge activate female pathwayExternal genitalia DHT masculinzation5 From what part of what germ layer do the gonads develop Is this the same in both sexes The germ layer where gonads develop are the mesoderm intermediate adjacent to developing kidney Gonads go through a bipotential stage neither male or female So they are in the same place for both sexes6From what cells do the sperm and oocytes develop Is this the same in both sexesPuberty sex cords hallow to form seminiferous tubules germ cells to these tubes differentiate into spermOocytes7Where is the gene for maleness located in mammals What is this gene called full name
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