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38 Cards in this Set
- Front
- Back
Chromosome theory of heredity
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a unifying theory stating that inheritance patterns may be generally explained by assuming that genes are located in specific sites on chromosomes
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Nondisjunction
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the failure of homologs (at meiosis) or sister chromatids (at mitosis) to separate properly to opposite poles
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Haploid
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a cell having one chromosome set or an organism composed of such cells
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Diploid
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a cell having two chromosome sets or an individual organism having two chromosome sets in each of its cells
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Heterochromatin
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densely staining condensed chromosomal regions, believed to be for the most part genetically inert
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Euchromatin
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a chromosomal region that stains normally; thought to contain the normally functioning genes
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Telocentric
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a chromosome having the centromere at one end
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Acrocentric
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a chromosome having the centromere located slightly nearer one end than the other
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Metacentric
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a chromosome having its centromere in the center
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Satellite DNA
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any type of highly repetitive DNA; formerly defined as DNA forming a satellite band after cesium chloride density-gradient centrifugation
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Nucleolar organizers (NO)
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a region (or regions) of the chromosome set that is physically associated with the nucleolus and contains rRNA genes
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Chromosome bands
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transverse stripes on the chromosomes of many organisms, revealed by special staining procedures
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Polytene chromosomes
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a giant chromsome in specific tissues of some insects, produced by an endomitotic process in which the multiple DNA sets remain bound in a haploid number of chromosomes
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Chromocenter
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the point at which the polytene chromosomes appear to be attached together
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Bands
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transverse stripes on chromosomes revealed by various stains
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FISH (fluorescence in situ hybridization)
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in situ hybridization with the use of a probe coupled with a fluorescent molecule
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Nucleosomes
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the basic unit of eukaryotic chromosome structure; a ball of eight histone molecules that is wrapped by two coils of DNA
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Histones
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a type of basic protein that forms the unit around which DNA is coiled in the nucleosomes of eukaryotic chromosomes
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Solenoid structure
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the supercoiled arrangement of DNA in eukaryotic nuclear chromosomes that is produced by coiling of the continuous string of nucleosomes
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Scaffold
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the central framework of a chromosome to which DNA solenoid is attached as loops; composed largely of topoisomerase
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Scaffold attachment region (SAR)
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positions along DNA at which the DNA is anchored to the central scaffold of the chromosome
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mtDNA
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mitochondrial DNA
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Cytohet
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a cell containing two genetically distinct types of a specific organelle
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Cytoplasmic segregation
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segregation in which genetically different daughter cells arise from a progenitor that is a cytohet
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Mitosis
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a type of nuclear division (occuring at cell division) that produces two daughter nuclei identical with the parent nucleus
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Dyads
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a pair of sister chromatids joined at the centromere, as in the first division of meiosis
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Bivalents
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two homologous chromosomes paired at meiosis
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Sister chromatids
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the juxtaposed pair of chromatids arising from replication of a chromosome
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Tetrad
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four homologous chromatids in a bundle in the first meiotic prophase and metaphse
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Synaptonemal complexes
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a complex structure that unites homologs during prophase of meiosis
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Crossing over
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the exchange of corresponding chromosome parts between homologs by breakage and reunion
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Nuclear Spindle
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the set of microtubules that forms between the poles of a cell during nuclear division; the function of the nuclear spindle is to segregate the chromosomes or chromatids to the poles
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Kinetochore
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a complex of proteins to which a nuclear spindle fiber attaches
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Chiasma
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a cross-shaped structure commonly observed between nonsister chromatids in meiosis;
the site of crossing over |
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Daughter cells
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two identical cells formed by the asexual division of a cell
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Meoisis
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two successive nuclear divisions (with corresponding cell divisions) that produce gametes that have one-half of the genetic material of the original cell
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Meiocytes
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cell in which meiosis takes place
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Gametes
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a specialized haploid cell that fuses with a gamete of the opposite sex or mating type to form a diploid zygote
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