Key Terms – Cell Reproduction
- anaphase
- the stage of mitosis during which sister chromatids are separated from each other
- aneuploid
- an individual with an error in chromosome number; includes deletions and duplications of chromosome segments
- autosome
- any of the non-sex chromosomes
- binary fission
- the process of prokaryotic cell division
- cell cycle
- the ordered sequence of events that a cell passes through between one cell division and the next
- cell plate
- a structure formed during plant-cell cytokinesis by Golgi vesicles fusing at the metaphase plate; will ultimately lead to formation of a cell wall to separate the two daughter cells
- centriole
- a paired rod-like structure constructed of microtubules at the center of each animal cell centrosome
- chiasmata
- (singular = chiasma) the structure that forms at the crossover points after genetic material is exchanged
- chromosome inversion
- the detachment, 180° rotation, and reinsertion of a chromosome arm
- cleavage furrow
- a constriction formed by the actin ring during animal-cell cytokinesis that leads to cytoplasmic division
- crossing over
- (also, recombination) the exchange of genetic material between homologous chromosomes resulting in chromosomes that incorporate genes from both parents of the organism forming reproductive cells
- cytokinesis
- the division of the cytoplasm following mitosis to form two daughter cells
- diploid
- describes a cell, nucleus, or organism containing two sets of chromosomes (2n)
- fertilization
- the union of two haploid cells typically from two individual organisms
- G0 phase
- a cell-cycle phase distinct from the G1 phase of interphase; a cell in G0 is not preparing to divide
- G1 phase
- (also, first gap) a cell-cycle phase; first phase of interphase centered on cell growth during mitosis
- G2 phase
- (also, second gap) a cell-cycle phase; third phase of interphase where the cell undergoes the final preparations for mitosis
- gamete
- a haploid reproductive cell or sex cell (sperm or egg)
- gametophyte
- a multicellular haploid life-cycle stage that produces gametes
- gene
- the physical and functional unit of heredity; a sequence of DNA that codes for a specific peptide or RNA molecule
- genome
- the entire genetic complement (DNA) of an organism
- germ cell
- a specialized cell that produces gametes, such as eggs or sperm
- haploid
- describes a cell, nucleus, or organism containing one set of chromosomes (n)
- homologous chromosomes
- chromosomes of the same length with genes in the same location; diploid organisms have pairs of homologous chromosomes, and the members of each pair come from different parents
- independent assortment
- random separation of maternal and paternal chromosomes, leading to genetic diversity in the resulting gametes
- interkinesis
- a period of rest that may occur between meiosis I and meiosis II; there is no replication of DNA during interkinesis
- interphase
- the period of the cell cycle leading up to mitosis; includes G1, S, and G2 phases; the interim between two consecutive cell divisions
- karyogram
- the photographic image of a karyotype
- karyokinesis
- first portion of mitotic phase, nuclear division
- karyotype
- the number and appearance of an individuals chromosomes, including the size, banding patterns, and centromere position
- kinetochore
- a protein structure in the centromere of each sister chromatid that attracts and binds spindle microtubules during prometaphase
- life cycle
- the sequence of events in the development of an organism and the production of cells that produce offspring
- locus
- the position of a gene on a chromosome
- meiosis
- a nuclear division process that results in four haploid cells
- meiosis I
- the first round of meiotic cell division; referred to as reduction division because the resulting cells are haploid
- meiosis II
- the second round of meiotic cell division following meiosis I; sister chromatids are separated from each other, and the result is four unique haploid cells
- metaphase
- the stage of mitosis during which chromosomes are lined up at the metaphase plate
- metaphase plate
- the equatorial plane midway between two poles of a cell where the chromosomes align during metaphase
- mitosis
- the period of the cell cycle at which the duplicated chromosomes are separated into identical nuclei; includes prophase, prometaphase, metaphase, anaphase, and telophase
- mitotic phase
- the period of the cell cycle when duplicated chromosomes are distributed into two nuclei and the cytoplasmic contents are divided; includes mitosis and cytokinesis
- mitotic spindle
- the microtubule apparatus that orchestrates the movement of chromosomes during mitosis
- monosomy
- an otherwise diploid genotype in which one chromosome is missing
- nondisjunction
- the failure of synapsed homologs to completely separate and migrate to separate poles during the first cell division of meiosis
- origin
- the region of the prokaryotic chromosome at which replication begins
- polyploid
- an individual with an incorrect number of chromosome sets
- prometaphase
- the stage of mitosis during which mitotic spindle fibers attach to kinetochores
- prophase
- the stage of mitosis during which chromosomes condense and the mitotic spindle begins to form
- quiescent
- describes a cell that is performing normal cell functions and has not initiated preparations for cell division
- recombinant
- describing something composed of genetic material from two sources, such as a chromosome with both maternal and paternal segments of DNA
- reduction division
- a nuclear division that produces daughter nuclei each having one-half as many chromosome sets as the parental nucleus; meiosis I is a reduction division
- S phase
- the second, or synthesis phase, of interphase during which DNA replication occurs
- septum
- a wall formed between bacterial daughter cells as a precursor to cell separation
- somatic cell
- all the cells of a multicellular organism except the gamete-forming cells
- sporophyte
- a multicellular diploid life-cycle stage that produces spores
- synapsis
- the formation of a close association between homologous chromosomes during prophase I
- telophase
- the stage of mitosis during which chromosomes arrive at opposite poles, decondense, and are surrounded by new nuclear envelopes
- tetrad
- two duplicated homologous chromosomes (four chromatids) bound together by chiasmata during prophase I
- translocation
- the process by which one segment of a chromosome dissociates and reattaches to a different, nonhomologous chromosome
- trisomy
- an otherwise diploid genotype in which one entire chromosome is duplicated
- X inactivation
- the condensation of X chromosomes into Barr bodies during embryonic development in females to compensate for the double genetic dose
- zygote
- the initial diploid cell formed when two haploid gametes, usually an egg and a sperm, fuse during sexual reproduction