Concepts of Biology-Ch.8
Terms
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- Mitosis
- Nuclear division mechanism that maintains the parental chromosome number for forthcoming daughter cells. Basis of growth, tissue repair, and often asexual reproduction of eukaryotes.
- Meiosis
- Only nuclear division process that halves the chromosome number of a parental cell, to the haploid number. Forms gametes in animals and spores in plants.
- Chromosome
- A coherent structure consisting of a DNA molecule and associated proteins.
- Chromatid
- Two identical DNA molecules (and associated proteins) attached at the centromere until they are separated from each other at mitosis or meiosis; each is then a separate chromosome.
- Centromere
- Constricted part of a chromosome to which spindle microtubules attach.
- Interphase
- Cell cycle interval between nuclear divisions; a cell grows in mass and roughly doubles the number of cytoplasmic components. DNA replication occurs during the interphase that precedes mitosis.
- Prophase
- Of mitosis, a stage when duplicated chromosomes start to condense, a spindle forms, and the nuclear envelope starts to break up. Duplicated pairs of centrioles move to opposite spindle poles. In prophase I of meiosis, crossing over also occurs.
- Metaphase
- Of meiosis I, stage when all pairs of homologous chromosomes have become positioned at the spindle equator. Of mitosis or meiosis II, all duplicated chromosomes are positioned at the spindle equator.
- Anaphase
- Of mitosis, stage when sister chromatids of each chromosome move to opposite spindle poles. During anaphase I (meiosis), each duplicated chromosome and its homologue move to opposite poles. During anaphase II, sister chromatids of each chromosome move to opposite poles.
- Telophase
- Of meiosis I, a stage when one member of each pair of homologous chromosomes reaches a spindle pole. Of mitosis and of meiosis II, the stage when chromosomes decondense into threadlike structures and daughter nuclei form.
- Diploid
- Total chromosome number in cells that have a pair of each type of chromosome characteristic of the species.
- Haploid
- Total chromosome number in cells that have one of each type of chromosome characteristic of the species.