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41 Cards in this Set
- Front
- Back
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asexual reproduction
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mitosis
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daughter cells
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products when one cell becomes 2 genetically identical cells
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sexual reproduction
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meiosis
mom + dad = zygote |
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homologous
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-pairs of chromosomes that look identical.
-1 of each pair comes from each parent. -same size, genes, position -NOT identical |
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alleles
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two copies of each gene
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sister chromatids
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result of replication
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homologous chromosomes
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inherited from parents
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somatic cells
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-body cells
-diploid -46 chromosomes |
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autosomes
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chromosomes that are not sex chromosomes
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asexual reproduction
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mitosis
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daughter cells
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products when one cell becomes 2 genetically identical cells
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sexual reproduction
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meiosis
mom + dad = zygote |
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alleles
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two copies of each gene
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meiosis
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-DNA replicates to make sister chromatids
-homologous chromosomes pair up then separated into cells -sister chromatids separate |
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sister chromatids
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result of replication
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homologous chromosomes
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inherited from parents
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somatic cells
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-body cells
-diploid -46 chromosomes |
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autosomes
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chromosomes that are not sex chromosomes
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X chromosome
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large, many important genes
required for living |
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Y chromosome
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tiny and useless
SRY gene- turned on in embryo directs getinal cells to form testes |
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zygote
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-first cell of a new individual
-diploid |
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eggs and sperm
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-Gametes
-Somatic cells in ovaries and testes -haploid |
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haploid
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1/2 number of chromosomes
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fertilization
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fusion of gametes to produce the first cell of a new individual
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1st division of meiosis
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one pair of sisters goes to each daughter cell
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2nd division of meiosis
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sisters separate
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prophase 1
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-chromosomes condense
-spindle forms -homologous chrom pair lengthwise -tetrads form |
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synapsis
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homologous chromosomes pair lengthwise
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tetrads
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-formed by aligning 4 chromatids
-two copies of each of the 2 homologous chromosomes |
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chiasmata
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homologous chromosomes appear to be constricted/crossed
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crossing over
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-locations wehre homologous chrom. are broken, exchanged, and rejoined
-creates unique chromosomes -mixture of both maternal and paternal chrom. |
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prophase 1
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-spindle microtubules are attached to a kinetochore on each pair of daughters
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metaphase 1
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tetrads (23 in humans) align
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Anaphase 1
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Pairs of sister chromatids are drawn to each pole
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Telophase I and cytokensis
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Daughter cells are formed
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AFTER meiosis 1
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-each cell has 46 chromosomes
-23 pairs of sister chromatids (identical) |
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Meiosis II
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chromosomes dont replicate again
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Prophase II
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-each cell has 23 pairs of sister chromatids corresonding to each chromosome
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AFTER meiosis II
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-gametes now have 1 copy of each homolgous chromosome
-either paternal or maternal -develop into sperm or egg |
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Genetic variation occurs when?
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separation of sister chromatid pairs during meiosis I
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ways to divide paternal and maternal
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-two chrom. from same parent
-one from each =4 ways |
