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41 Cards in this Set

  • Front
  • Back
Genes on the Same Chromosome
metacentric chromosome
chromosome wth its centromere in the middle - V shape, arms are equal length
submetacentric chromosome
a chromosome with a somewhat off-center centromere, J-shape
acrocentric chromosome
a chromosome with a centromere very close to one end - "I" Shaped
chromosome that lacks a centromere
dicentric chromosome
a chromosome with 2 centromeres
dosage compensation
a mechanism regulating x-linked genes such that their activies are equal in males and females; in mammals, random inactivation of one x chromosome in females results in equal amounts of the products of x-linked genes in males and females
X inactivation
in mammals, the genetic inactivation of all X chromosomes except one in each cell lineage, except the one in very early embryo
barr body
in certain female cells, a densely staining heterochromatic body in the nucleus of interphase cells observed in a microscope
an individual that has cells of two or more different genotypes
psuedoautosomal regions
the regions of shared X-Y homology, where crossing-over regualarly occurs during spermatogenesis (PARp - short & PARq - long)
transcription factor
a protein that stimulates transcription of its target genes
Testis-Determing Factor (TDF)
the master sex-determining gene SRY, that triggers male embryonic development
an otherwise diploid organism that has an extra copy of an individual chromosome
three sets of chromosomes (69 in humans)
four sets of chromosomes (92 in humans)
a cell or an organism having a chromosome number that is an exact multiple of the haploid number
a cell or organism in which the chromosome number is not an exact multiple of the haploid number, more generally, aneuploidy is a condition where specific chromosomes or genes are present in fewer or extra copies
balanced translocation
a euploid condition in which nonhomologous chromosomes have an interchange of parts, but all parts are present
unbalanced translocation
an aneuploid condition in which some part of the genome is missing
when an otherwise diploid organism is missing a copy of an individual chromosome
Non-Fatal Trisomies
Trisomy 13 (fetus alive for a few days)
Trisomy 18 (fetus alive for a few days)
Trisomy 21 (Down Syndrome)
Down Syndrome (Down's Syndrome)
Trisomy 21- usually caused by nondisjunction in oogenesis of eggs. Drastically increased chances of occurance in older mothers
structure formed by three homologous chromosomes in meiosis I in a triploid or trisomic chromosome when each homolog is paired along part of its length with the first one and then the ther of the homologs
Trisomy-X Syndrome
47,XXX - phenotypically female, usually rather normal
Double-Y Syndrome
47, XYY - male, tall, phenotypically and psychologically normal
Kleinfelter Syndrome
47, XXY - male, tall, sterile, mild mental impairment
Turner Syndrome
45, X - female, sterile, short
a segment of a chromosome that is missing
abnormal chromosomes that have a region that is present twice
tandem duplication
a chromosome where the duplicated segment is present in the same orientation immediately adjacent to teh normal region in the chromosome
chimeric gene
composite gene formed by the joining of two different parts of two genes
inversion loop
loop structure formed by synapsis of homologous genes in a pair of chromosomes, one of which contains an inversion
paracentric inversion
the inversion of a chromosome that does not include the centromere. The products of crossing over include a dicentric and an acentric chromosome
pericentric inversion
an inversion of a chromosome that contains the centromere. the products of pericentric inversion are both monocentric chromosomes
a chromosomal aberration resulting from the interchange of parts between nonhomologous chromosomes
an organism that is heterozygous for a reciprocal translocation usually produces only about half as many offspring as normal
adjacent-1,2 segregation
type of segregation from a heterozygous reciprocal translocation in which a stucturally normal chromosome segregates with a translocated chromosome
alternate segregation
segregation from a heterozygous reciprocal translocation in which both pairs of the reciprocal translocation separate from both nontranslocated chromosomes in the first meiotic division
all chromosomes in the polyploid species derive froma single diploid ancestral species
a polyploid formed from the hybridization of two different species