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39 Cards in this Set
- Front
- Back
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somatic cells
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body cells that increase from cell division
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mitosis
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the division of the nucleus in somatic cells
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cytokinesis
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the division of the cytoplasm of cells
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apoptosis
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programmed cell death which decreases the number of cells
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cell cycle
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an orderly set of stages that take places between the time a cell divides and the time the resulting cells also divide
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interphase
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the time when a cell carries on its usual functions
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cyclin
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a signal that increases and decreases as the cell cycle continues. it has to be present for the cell to proceed from the G2 stage to the M stage
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chromatin
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a tangled mass of thin threads in the nucleus
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chromosomes
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highly compacted structures that is formed by coiled, looped, and condensed chromatin
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diploid (2n) number
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a number that contains pairs of chromosomes
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haploid (n) number
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contains only one of each kind of chromosome
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duplicated chromosome
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a chromosome that is composed of two sister chromatids held together in a centromere
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centromere
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a region that holds together 2 sister chromatids
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sister chromatids
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genetically identical chromosomes
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daughter chromosomes
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chromosomes where the centromeres have divided and the sister chromosomes have separated
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spindle
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many fibers, each composed of a bundle of microtubules
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centioles
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barrel-shaped organelles in a centrosome
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aster
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an array of short microtubules in a centrosome
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prophase
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a stage in which the centrosomes begin moving away from each other toward opposite ends of the nucleus
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metaphase
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a phase in which the fully formed spindle consists of poles, asters, and fibers
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equator
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a plane perpendicular to the axis of the spindle and equidistant from the poles
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anaphase
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a phase in which the centromeres uniting the sister chromatids divide
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telophase
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a phase in which the spindle disappears, and nuclear envelope components reassemble around the daughter chromosomes
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cell plate
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structure that precedes the formation of the cell wall as a part of cytokinesis in plant cells
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cleavage furrow
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indentation that begins the process of cleavage, by which animal cells undergo cytokinesis
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crossing-over
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exchange of corresponding segments of genetic material between nonsister chromatids of homologous chromosomes during synapsis of meiosis
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fertilization
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union of a sperm nucleus and an egg nucleus, which creates the zygote with the diploid number of chromosomes
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gamete
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haploid sex cell; the egg or a sperm that join during fertilization to form a zygote
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homologous chromosome
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similarly constructed chromosomes with the same shape and that contain genes for the same traits; also called homologues
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independent assortment
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alleles of unlinked genes segregate independently of each other during meiosis so that the gametes contain all possible combinations of alleles
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interkinesis
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period of time between meiosis I and meiosis II during which no DNA replication takes place
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meiosis
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type of nuclear division that occurs as part of sexual reproduction in which the daughter cells receive the haploid number of chromosomes in varied combinations
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nondisjunction
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failure of homologous chromsomes or daughter chromosomes to separate during meiosis I and meiosis II, respectively
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oogenesis
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production of an egg in females by the process of meiosis and maturation
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polar body
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nonfunctioning daughter cell, formed during oogenesis, that has little cytoplasm
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secondary oocyte
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in oogenesis, the functional prodcut of meiosis I; becomes the egg
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synapsis
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pairing of homologous chromsomes durign prophase I of meiosis
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spermatogenesis
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production of sperm in males by the process of meiosis and maturation
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zygote
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diploid cell formed by the union of sperm and egg; the product of fertilization
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