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10 Cards in this Set
- Front
- Back
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What is the differene between homologous pairs and sister chromatids?
Why are they important to differentiate? |
Homologous pairs are the 2 sets of chromosomes one from each parent, Homologous chromosomes (homologues or bivalents) = paired chromosomes that code for the same traits
1 inherited from each parent same length, same banding pattern genes may code for different variations of same trait Sister Chromatids are the two sides of a single chromosome. Chromatid = single strand of chromosome Sister chromatids = 2 strands of genetically identical chromosomes Attached at centromere During nuclear division: Sister chromatids separate to form 2 daughter chromosomes Because Homologous pairs are 2 separate chromosomes. |
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How do mitosis and meiosis differ?
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Mitosis:
1 nuclear division 2 daughter cells (diploid) Identical to parent Meiosis: 2 nuclear divisions 4 daughter cells (haploid) NOT identical to parent |
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What types of cells are the products of meiosis?
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Gametes
Meiosis = nuclear division that cuts chromosome # in half from diploid (2n) to haploid (n) Occurs during production of reproductive cells Gametes = reproductive cells (sperm & egg) = haploid (n) Sexual reproduction = fusion of 2 gametes (n + n) forms a diploid (2n) organism = zygote |
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What is independent assortment?
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Chromosome separation is random.
Homologous chromosomes separate independently & randomly When homologues or bivalents align at cell equator, maternal or paternal homologue may be oriented toward either pole. Result = several (2^3= 8) possible chromosome combinations. 2^23 = 8, 388, 608 combinations in humans. |
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What is spermatogenesis and oogenesis?
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Spermatogenesis is the process in which sperm cells are made.
Oogenesis is the process in which the egg cell is created. |
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What happens during prophase 1?
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Prophase I:
Nuclear envelope & nucleolus disappear 2 homologous chromosomes pair during synapsis to form bivalents Crossing over can occur |
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What is genetic recombination?
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Genetic recombination: offspring have different combination of chromosomes & genes than parents
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How do independent assortment and crossing over processes relate to genetic recombination?
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This is what allows for such a wide variety of genetic combinations.
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What is crossing over?
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Nonsister chromatids recombine genes during prophase I.
Exchange of genetic material between nonsister chromatids of a bivalent. |
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How are spermatogenesis and oogenesis different?
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Primary spermatocyte: diploid (2n) = 46 chromosomes
Secondary spermatocytes: = 23 duplicated chromosomes Sperm: haploid (n) = 23 chromosomes Primary oocytes: diploid (2n) = 46 chromosomes Secondary oocyte: = 23 DUPLICATED chromosomes Contains most of cytoplasm= nutrients for developing embryo Begins meiosis II & stops at metaphase II If sperm enters secondary oocyte, meiosis II is completed |
