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28 Cards in this Set
- Front
- Back
Heredity
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the transmission of traits from one generation to the next
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Genetics
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the scientific study of heredity and hereditary variation
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Gene
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hereditary units that hold genetic information; passed on from parent to offspring; segments of DNA
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Locus
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a gene’s specific location along the length of a chromosome
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Asexual reproduction
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a process in which a single individual is the sole parent and passes copies of all its genes on to its offspring; offspring is usually genetically identical to parent
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Clone
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a group of genetically identical individuals
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Sexual reproduction
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a reproductive process that results in greater variation than asexual reproduction; two parents give rise to offspring that have unique combinations of genes inherited from the two parents; offspring differ from both parents and siblings genetically
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Life cycle
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the generation-to-generation sequence of stages in the reproductive history of an organism, from conception to production of its own offspring
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Karyotype
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a method of organizing the chromosomes of a cell in relation to number, size, and type; usually prepared using lymphocytes
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Homologous chromosomes
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the chromosomes that make up a pair – that have the same length, centromere position, and staining pattern; also called homologues; chromosomes of each pair carry genes controlling the same inherited characteristics
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Sex chromosomes
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chromosomes X and Y (nonhomologous chromosomes)
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Autosomes
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all chromosomes except sex chromosomes
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Gametes
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sex cells that contain a single set of chromosomes and is called haploid
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Syngamy
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another term for fertilization; union of gametes to form a zygote
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Meiosis
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a form of cell division in which the number of a haploid number of chromosomes is passed on from cell to cell; occurs only in the ovaries and testes
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Synapsis
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a process during prophase I in which the duplicated chromosomes pair with their homologues
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Tetrad
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the grouping of the four closely associated chromatids of a homologous pair that are visible through a light microscope
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Chiasmata
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X-shaped regions visible through the light microscope that represent a crossing of nonsister chromatids; physical manifestations of crossing over
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Interphase I
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stage during which chromosomes replicate, resulting in two genetically identical sister chromatids that remain attached
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Prophase I
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stage of meiosis that involves the disintegration of the nuclear envelope, condensation of the chromosomes and synapsis; centrosomes also move apart and begin to form spindle fibers; composes roughly 90% of the time required for meiosis
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Metaphase I
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stage of meiosis in which chromosomes are arranged on the metaphase plate in homologous pairs
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Anaphase I
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stage of meiosis in which the spindle apparatus moves the chromosomes toward the poles of the cell
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Telophase I and cytokinesis
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stages of meiosis that generally occur concurrently; each pole has a haploid chromosome set, but each chromosome still has two sister chromatids; cleavage furrows form in animal cells and cell plates form in plant cells
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Prophase II
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stage of meiosis in which the spindle apparatus forms and chromosomes progress toward the metaphase II plate
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Metaphse II
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stage of meiosis that resembles mitotic metaphase; chromosomes line up at the metaphase II plate
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Anaphase II
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stage of meiosis in which the centromeres of sister chromatids separate and the sister chromatids of each pair move toward opposite poles of the cell
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Telophase II and cytokinesis
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stage of meiosis in which nuclei form at opposite poles of the cell and cytokinesis occurs; results in four daughter cells which each possess a haploid number of unreplicated chromosomes
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Crossing over
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a process the produces individual chromosomes that combine genes inherited from our two parents; occurs during prophase of meiosis I
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