Genetics Vocab Ch. 2 Of Pierce 3Rd Ed.

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prokaryote

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unicellular organism with a simple cell structure. include eubacteria and archaea

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eukaryote

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organism with a complex cell structure including a nuclear envelope and membrane-bounded organelles. one of the three primary divisions of life, eukaryotes include unicellular and multicellular forms

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eubacteria

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one of the three primary divisions of life. eubacteria consists of unicellular organisms with prokaryotic cells and include most of the common bacteria

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archaea

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one of the three primary divisions of life. archaea consist of unicellular organisms with prokaryotic cells

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nucleus

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space in eukaryotic cells that is enclosed by the nuclear envelope and contains the chromosomes

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histone

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low-molecular-weight protein found in eukaryotes that complexes with DNA to form chromosomes

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chromatin

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material found in the eukaryotic nucleus; consists of DNA and proteins

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homologous pair of chromosomes

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two chromosomes that are alike in structure and size and that carry genetic information for the same set of hereditary characteristics. one chromosome of a homologous pair is inherited from the male parent and the other is inherited from the female parent

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diploid

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possessing two sets of chromosomes (two genomes)

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haploid

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possessing a single set of chromosomes (one genome)

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telomere

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stable end of a chromosome

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origin of replication

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site where DNA synthesis is initiated

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sister chromatids

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two copies of a chromosome that are held together at the centromere. each chromatic consists of a single DNA molecule

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cell cycle

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stages through which a cell passes from one cell division to the next

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checkpoint

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a key transition point at which progression to the next stage in the cell cycle is regulated

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interphase

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period in the cell cycle between the cell divisions. in interphase, the cell grows, develops, and prepares for cell division

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M phase

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mitotic phase. period of active cell division; includes mitosis (nuclear division) and cytokinesis (cytoplasmic division)

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mitosis

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process by which the nucleus of a eukaryotic cell divides

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cytokinesis

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process by which the cytoplasm of a cell divides

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prophase

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stage of mitosis. in prophase, the chromosomes contract and become visible, the cytoskeleton breaks down, and the mitotic spindle begins to form

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prometaphase

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stage of mitosis. in prometaphase, the nuclear membrane breaks down and the spindle microtubules attach to the chromosomes

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metaphase

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stage of mitosis. in metaphase, chromosomes align in the center of the cell

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anaphase

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stage of mitosis in which chromatids separate and move toward the spindle poles

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telophase

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stage of mitosis. in telophase, the chromosomes arrive at the spindle poles, the nuclear membrane re-forms, and the chromosomes relax and lengthen

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meiosis

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process in which chromosomes of a eukaryotic cell divide to give rise to haploid reproductive cells. consists of two divisions; meiosis I and meiosis II

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fertilization

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fusion of gametes, or sex cells, to form a zygote

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prophase I

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stae of meiosis I. in prophase I, chromosomes condense and pair, crossing over takes place, the nuclear membrane breaks down, and the spindle forms

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synapsis

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close pairing of homologous chromosomes

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bivalent

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refers to a synapsed pair of homologous chromosomes

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tetrad

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the four products of meiosis; all four chromatids of a homologous pair of chromosomes

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crossing over

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exchange of genetic material between homologous but nonsister chromatids

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metaphase I

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stage of meiosis I. in metaphase I, homologous pairs of chromosomes align in the center of the cell

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anaphase I

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stage of meiosis I. in anaphase I, homologous chromosomes separate and move toward the spindle poles

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telophase I

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stage of meiosis I. in telophase I, chromosomes arrive at the spindle poles

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interkinesis

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period between meiosis I and meiosis II

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prophase II

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stage of meiosis after interkinesis. in prophase II, chromosomes condense, the nuclear membrane breaks down, and the spindle forms. some cells skip this stage

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metaphase II

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stage of meiosis II. in metaphase II, individual chromosomes align on the metaphase plate

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anaphase II

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stage of meiosis II. in anaphase II, chromatids separate and move toward the spindle poles

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telophase II

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stage of meiosis II. in telophase II, chromosomes arrive at the spindle poles

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recombination

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sorting of alleles into new combinations

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cohesin

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molecule that holds the two sister chromatids of a chromosome together. the breakdown of cohesin at the centromeres enables the chromatids to separate in anaphase of mitosis and anaphase II of meiosis.

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spermatogenesis

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sperm production in animals

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spermatogonium

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diploid cell in the testis; capable of undergoing meiosis to produce a sperm

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primary spermatocyte

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spermatogonium that has entered prophase I

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secondary spermatocyte

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product of meiosis I in male animals

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spermatid

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immediate product of meiosis II in spermatogenesis; matures to sperm

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oogenesis

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egg production in animals

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oogonium

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diploid cell in the ovary; capable of undergoing meiosis to produce an egg cell

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primary oocyte

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oogonium that has entered prophase I

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secondary oocyte

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one of the products of meiosis I in female animals; receives most of the cytoplasm

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first polar body

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one of the products of meiosis I in oogenesis; contains half the chromosomes but little of the cytoplasm

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ovum

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final product of oogenesis

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second polar body

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one of the products of meiosis II in oogenesis; contains a set of chromosomes but little of the cytoplasm

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microsporocyte

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diploid reproductive cell in the stamen of a plant; undergoes meiosis to produce four haploid microspores.

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microspore

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haploid product of meiosis in plants

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megasporocyte

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in the ovary of a plant, a diploid reproductive cell that undergoes meiosis to produce haploid macrospores

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megaspore

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one of teh four products of meiosis in plants