moregenetics - 7 15.3(282-284 A Discuss how gender is...

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7) 15.3 (282-284) A. Discuss how gender is determined in mammals, birds, and some insects. X-Y Z-W XO haplo-diploid B. How are X chromosomes that condense into Barr bodies inactivated? In what way can female mammals be described as “mosaic”? A) XY -The sex of humans and mammals is determined by whether they have a Y chromosome or not. -Males have XY -Females have XX -Half of the male’s gametes have the X chromosome and half have the Y chromosome. -Random fertilization happens when any random gamete fertilizes an ovum with either X chromosome. -So there is a 50% chance that the offspring will be a girl, and a 50% chance that the offspring will be a boy. -The Y chromosome in humans has a gene that is required as trigger for the development of testes called SRY. XO -The sex is determined like this in many insects. -Females have 2 X chromosomes and males have only 1 X chromosome. -Half of the male’s gametes have the X chromosome, and half do not have a sex chromosome. -Like for X-Y in humans, random fertilization determines whether the offspring will be female or male.
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moregenetics - 7 15.3(282-284 A Discuss how gender is...

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