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mitosis
| Term | Definition |
|---|---|
| alternation of generations | life-cycle type in which the diploid and haploid stages alternate |
| chiasmata | (singular, chiasma) the structure that forms at the crossover points after genetic material is exchanged |
| cohesin | proteins that form a complex that seals sister chromatids together at their centromeres until anaphase II of meiosis |
| crossover | exchange of genetic material between nonsister chromatids resulting in chromosomes that incorporate genes from both parents of the organism |
| fertilization | union of two haploid cells from two individual organisms |
| gametophyte | a multicellular haploid life-cycle stage that produces gametes |
| germ cells | specialized cell line that produces gametes, such as eggs or sperm |
| interkinesis | (also, interphase II) brief period of rest between meiosis I and meiosis II |
| life cycle | the sequence of events in the development of an organism and the production of cells that produce offspring |
| meiosis | a nuclear division process that results in four haploid cells |
| meiosis I | first round of meiotic cell division; referred to as reduction division because the ploidy level is reduced from diploid to haploid |
| meiosis II | second round of meiotic cell division following meiosis I; sister chromatids are separated into individual chromosomes, and the result is four unique haploid cells |
| recombination nodules | protein assemblies formed on the synaptonemal complex that mark the points of crossover events and mediate the multistep process of genetic recombination between nonsister chromatids of a homologous pair |
| reduction division | nuclear division that produces daughter nuclei each having one-half as many chromosome sets as the parental nucleus; meiosis I is a reduction division |
| somatic cell | all the cells of a multicellular organism except the gametes or reproductive cells |
| spore | haploid cell that can produce a haploid multicellular organism or can fuse with another spore to form a diploid cell |
| sporophyte | a multicellular diploid life-cycle stage that produces haploid spores by meiosis |
| synapsis | formation of a close association between homologous chromosomes during prophase I |
| synaptonemal complex | protein lattice that forms between homologous chromosomes during prophase I, supporting crossover |
| tetrad | two duplicated homologous chromosomes (four chromatids) bound together by chiasmata during prophase I |
| reduction division | the first meiotic cell division in the formation of sex cells in which the number of chromosomes in each cell is halved. |
| sister chromatids | aligned at the metaphase plate of the mitotic spindle |
| homologous chromosomes | a set of one maternal and one paternal chromosome that pair up with each other inside a cell during fertilization |
| random assembly of homologous chromosomes | the pairs of homologous chromosome are divided in half to form haploid cells |
| gametes | a mature haploid male or female germ cell which is able to unite with another of the opposite sex in sexual reproduction to form a zygote |
| karyotype | A karyotype is the general appearance of the complete set of chromosomes in the cells of a species or in an individual organism, mainly including their sizes, numbers, and shapes |
| gonads | the primary reproductive organs, are the testes in the male and the ovaries in the female |
| germ cells | Germ cells are cells that create reproductive cells |
| genetic recombination | the exchange of genetic material between different organisms which leads to production of offspring with combinations of traits that differ from those found in either parent |
| methods of increasing genetic diversity | mutation, gene duplication, and other various processes |
| haploid | (of a cell or nucleus) having a single set of unpaired chromosomes. |
| diploid | (of a cell or nucleus) containing two complete sets of chromosomes, one from each parent. |
| ploidy | the number of sets of chromosomes in a cell, or in the cells of an organism. |