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26 Cards in this Set
- Front
- Back
homologous
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chromosomes that have a corresponding chromosome from the opposite sex-parent (meaning the number of chromosomes from the male parent corresponds to the number from the female parent)
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diploid
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a cell that contains both sets of homologous chromosomes
-means "two sets"-two complete sets of chromosomes and two complete sets of genes |
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diploid number
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the way the number of chromosomes in a diploid cell are represented-uses 2N
ex. fruit fly had 8 chromosomes diploid number= 2N=8 |
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haploid
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cells that contain only a single set of chromosomes, and therefore only a single set of genes.
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haploid number
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haploid # for fruit fly (8 chromosomes)
N=4 |
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meiosis
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a process of reduction division in which the number of chromsomes per cell is cut in half throuh the separation of homologous chromosomes in a diploid cell.
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what are the two distinct stages of meiosis and what is the result by the end of the second stage?
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Meiosis I and meiosis II- the end result is 4 haploid cells with a diploid number of 4 (2N=4)
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Interphase I
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First step, prior to meiosis I. Cells undergo a round of DNA replication, forming duplicate chromosomes.(might not be visible)
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Name steps of meiosis in order of occurance.
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Prior to meiosis I: Interphase I
Meiosis I: Prophase I, Metaphase I, Anaphase I, Telephase I and cytokinesis Meiosis II: Prophase II, Metaphase II, Anaphase II, Telephase II and cytokinesis |
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Prophase I
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each chromosome pairs with its corresponding homologous chromosomes to form a tetrad. Crossing-over can occur here.
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Tetrad
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a structure formed during Prophase I that contains 4 chromatids.
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crossing-over
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as homologous chromosomes pair up and form tetrads in meiosis I (prophase I), they may exchange portions of their chromatids. Crossing-over results in the exchange of alleles between homologous chromosomes and produces new combinations of alleles.
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Metaphase I
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Spindle fibers attach to the chromsomes
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Anaphase I
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The fibers pull the homologous chromosomes toward opposite ends of the cell
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Telephase I and cytokinesis
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Nuclear membranes form. The cell separates into two cells, each with 2 chromosomes.
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Difference between meiosis I and meiosis II
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the chromosomes in meiosis I were replicated and so there was four, but at the start of meiosis II there are two chromosomes in each cell.
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prophase II
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meiosis I results in two haploid daughter cells, each with half the number of chromosomes as the original cell
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Metaphase II
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the (two) chromosomes line up in a similar way to the metaphase stage of mitosis.
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anaphase II
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the sister chromatids separate and move toward opposite ends of the cell
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telophase II and cytokinesis
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meiosis II results in four haploid daughter cells now contain just two chromosomes each
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gametes
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specialized cells in sexual reproduction
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sperm
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haploid gametes produced by male animals
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egg/egg cell
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female gamete in aniamls and some plants
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how is the cell division in females uneven?
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the egg receives most of the cytoplasm and the 3 polar bodies receive less
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polar bodies
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the other three cells produced in the female during meiosis that usually do not participate in reproduction
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What is the one major difference between mitosis and meiosis??
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mitosis results in the production of two genetically identical diploid cells, whereas meiosis produces four genetically different haploid cells
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