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32 Cards in this Set
- Front
- Back
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What does mitosis use cell reproduction for?
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cell repair, growth, development, replacement of old worn out cells, reproduction in unicellular organisms
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What does meiosis use cell reproduction for?
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gametes (egg cells, sperm cells, spores in plants)
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What are diploid cells?
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somatic cells (body cells): chromosomes occur in homologous pairs (2n)
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What are haploid cells?
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reproductive cells (germ cells or gametes): half of each homologous pairs of gametes (n)
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What is chromatin?
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a long thread like structure of DNA that condenses into chromosomes in preparation for cell division
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What is interphase?
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the interval between successive cell divisions divided into 3 phases (g1 phase, s-phase, g2 phase)
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What happens in the 1st gap period?
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growth, metabolism, proteins are synthesized, and organelles increase in number
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What happens in the second phase of interphase?
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DNA is synthesized and chromosomes are replicated
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What happens in the 2nd gap period?
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organelles replicate, proteins needed for cell division are synthesized, chromosomes begin to condense
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What happens in prophase?
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chromatin continues to condense into chromosomes, centrioles separate, spindle fibers form, nuclear envelope breaks down
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What happens in metaphase?
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replicated chromosomes line up along the center of the cell, each centromere attaches to a spindle fiber
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What happens in anaphase?
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sister chromatids are separated and each chromatid now becomes a chromosome
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What happens in telophase?
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chromosomes gather at opposite ends of the cell and 2 new nuclear envelopes form
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What happens in cytokinesis?
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cell pinches into 2 new cells called "daughter" cells which are genetically identical to the parent cell
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What is meiosis?
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2 nuclear divisions that produce 4 haploid cells each containing one of each kind of chromosome (1/2 of the homologous pair)
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What is synapsis?
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process when the homologous pairs come together and line up side by side as opposed to single file
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What is a tetrad?
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one pair of homologous pairs (each containing 4 chromatids) that lines up in a synapsis ex. XX
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What is crossing over?
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the exchange of genetic material between non-sister chromatids of a tetrad during meiosis 1
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Why are the daughter cells of meiosis not identical to the parents cells?
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because when the chromosomes line up in tetrads, chromatids cross-over and exchange genetic information
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What is a chiasma?
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the point where the chromatids join in crossing over (each tetrad forms 1 and usually more)
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What is independent assortment?
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gametes have different combinations (with reference to parents) of chromosomes
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What is fertilization?
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combining of chromosomes from genetically different gametes occurs
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What is different with mitosis in plants?
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there are no centrioles but there are spindle fibers, cytokinesis cannot occur because of the cell wall, and instead there is a formation of a cell plate; there are also vesicles
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What is a vesicle?
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a membranous sac
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What is oogogenesis?
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formation of female gametes (egg); occurs in the ovaries
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Why is the egg the largest cell produced in the female?
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because it must contain the nutrients to nourish the egg
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What happens after oogogenesis?
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the cytoplasm plus the organelles are concentrated into 1 cell (the egg- ovum), polar bodies die- once the egg is fertilized it will be nourished by the cytoplasm until it implants
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What is spermatogenesis?
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male gamete formation (sperm cells), occurs in the semiferous tubules of the testes, and is continuous and prolific with each ejaculation releasing
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What is the mid piece of a mature sperm cell?
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mitochondrion
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What happens to the sperm when the egg is fertilized?
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the mid piece and tail break off and only the head of the sperm cell penetrates the egg
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What is the m-phase?
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phase of cell division divided into mitosis and cytokinesis
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What are three ways genetic recombination occurs in sexual reproduction?
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independent assortment, crossing over, and fertilization
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