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38 Cards in this Set

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