Vocabulary #2 ¬¬

abortion	spontaneous or induced expulsion of the embryo or fetus from uterus.
aneuploidy	Having one extra or one less chromosome to the parental  number.
autosome	Any chromosome that is the same in males and females of the species.
crossing over	an interaction in which non-sister chromatids of a pair of homologous chromosomes break at corresponding sites and exchange segments.
deletion	At cytological level, loss of a segment from a chromosome.
disease	Outcome of infection mobilized fast enough and a pathogen's activities interfere with normal body functions.
double-blind study	investigators independently collect, then compare data.
duplication	Gene sequence repeated several to many hundreds or thousands of times. Even normal chromosomes have such sequences.
genetic abnormality	A rare or less common version of a heritable trait.
genetic disorder	Any inherited condition that causes mild to severe medical problems.
genetic recombination	any process that puts new genetic information into a DNA molecule.
homologous chromosome	Of cells with a diploid chromosome number, one of a pair of chromosomes identical in size, shape, and gene sequence. Nonidentical sex chromosomes (e.g., X and Y) also interact as homologues during meiosis.
in-vitro fertilization	Conception outside the body (''in glass'' petri dishes or test tubes).
independent assortment	each pair of homologous chromosomes are sorted before shipment to gametes independently of how the other pairs were sorted. Later modified to account for the disruptive effect of crossing over on linkages.
inversion	Part of a chromosome that became oriented in reverse, with no molecular loss.
karyotype	Preparation of metaphase chromosomes sorted by length, centromere location, other defining features.
linkage group	All genes on a chromosome.
mosaicism	Cells of same type express genes differently, so phenotypic differences emerge in same type of tissue. E.g., occurs by X chromosome inactivation in female mammals.
Non-disjunction	Failure of sister chromatids or a pair of homologous chromosomes to separate during meiosis or mitosis.
polyploidy	Having three or more of each type of chromosome in the nucleus of a eukaryotic cell at interphase.
reciprocal cross	A paired cross. In the first cross, one parent displays the trait of interest , the other parent displays it.
sex chromosome	A chromosome with genes that affect sexual traits. Depending on the species, somatic cells have one or two sex chromosomes of the same or different type (e.g., in mammals, XX females, XY males).
syndrome	A set of symptoms that may not individually be a telling clue but collectively , a genetic disorder or disease.
translocation	movement of a stretch of DNA to a new chromosomal location with no molecular loss. Of vascular plants, distribution of organic compounds by way of phloem.
X chromosome	A type of sex chromosome. An XX mammalian embryo becomes female; an XY pairing causes it to develop into a male.
Y chromosome	A type of sex chromosome. An XX mammalian embryo becomes female; an XY pairing causes it to develop into a male.