Chapter 3-BB-1

Acrosome capped acrosome oogenesis oogenesis the

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Unformatted text preview: primary oocytes primary In humans, for example, about 1 million primary In occytes per ovary are produced before birth occytes The primary oocytes initiate meiosis I However, they enter into a dormant phase At puberty, primary oocytes are periodically At activated to progress through meiosis I activated They are arrested in _________until the female They becomes sexually mature becomes In humans, one oocyte per month is activated The division in meiosis I is asymmetric The producing two haploid cells of unequal size producing A large __________ oocyte large __________ A small ________ body small ________ The secondary oocyte enters meiosis II but is quickly arrested in The it it It is released into the oviduct An event called _________ If the secondary oocyte is fertilized The haploid egg and sperm nuclei then fuse to created the The diploid nucleus of a new individual diploid Gamete Formation in Plants Gamete The life cycles of plant species alternate between The two generations two Haploid, which is termed the gametophyte Haploid, gametophyte Diploid, which is termed the sporophyte Diploid, sporophyte Meiosis produces haploid cells called spores Spores divide by mitosis to produce the Spores gametophyte gametophyte diploid haploid diploid haploid For fertilization to occur, specialized cells within the male and female gametophytes must meet Fertilization in higher plants - a double Fertilization fertilization fertilization the endosperm (which uses a large amount the of plant resources) will develop only when an egg cell has been fertilized an After fertilization is complete The ovule develops into a seed The surrounding ovary develops into a fruit Which encloses one or more seeds Sex Determination Sex In many animal species, chromosomes play a role in sex determination In some insects, Males are XO and females are XX In other insects (fruit fly, for example) Males are XY and females are XX The sex chromosomes are designated Z and W The Males contain two Z chromosomes Males Females have one X and one Y chromosome Haplo-diploid system Males are known as the drones They are haploid Females include the worker bees and queen bees They are diploid Relationship between genetic trait and inheritance of a sex chromosome Cross Cross Results Original white Original eyed-male to redeyed-male eyed females F1 generation: F1 male to F1 female F2 generation: females females males males females males males Test Cross White-eyed male White-eyed to F1 female to All red-eyed flies 2,459 red-eyed 1,011 red-eyed 0 white eyedwhite 782 white-eyed Results females females males males females males males 129 red-eyed 132 red-eyed 88 white eyed88 86 white-eyed F1 male is Xw+Y F1 female is Xw+Xw + TEST CROSS Reciprocal crosses Reciprocal Crosses between different strains in which the Crosses sexes are reversed sexes These crosses reveal whether a trait is carried These on a sex chromosome or an autosome on X-linked traits do not behave identically in X-linked reciprocal crosses reciprocal Consider the following two crosses: Male is Xw+Y Female is XwXw Male is XwY Female is Xw+Xw+...
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This document was uploaded on 03/05/2014 for the course CELL 2050 at Tulane.

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