1 - Biol 241 2010 Lecture 3: Sex chromosomes and dosage...

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Biol 241 - 2010 Lecture 3: Sex chromosomes and dosage compensation I) Sexual reproduction , which greatly enhances genetic variation with species, requires mechanisms that result in sexual differentiation. A wide variety of genetic mechanisms have evolved in organisms leading to sexual dimorphism. A) Individuals that contain only male or female reproductive organs are unisexual (dioecious or gonochoric), whereas individuals that contain both male and female reproductive organs are bisexual (monoecious or hermaphroditic) and can produce both male and female gametes. B) The nematode worm Caenorhabditis elegans has two sexual phenotypes: males, which have only testes, and hermaphrodites, which have both testes and ovaries. Self-fertilization occurs in the hermaphrodites and produces primarily hermaphrodite offspring, with less than 1% male offspring. As adults, the males can mate with the hermaphrodites, producing about half male and half hermaphrodite offspring. II) Sex Determination (Chromosomal sex determination, genic sex determination, and temperature sex determination) A) The XX/XO ( Protenor ) mode of sex determination depends on the random
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This note was uploaded on 02/09/2010 for the course BIOL 241 taught by Professor Henrychang during the Spring '10 term at Purdue University-West Lafayette.

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1 - Biol 241 2010 Lecture 3: Sex chromosomes and dosage...

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