chromosome /chro·mo·some/ (kro´mah-sōm) in animal cells, a structure in the nucleus containing a linear thread of DNA which transmits genetic information and is associated with RNA and histones; during cell division the material composing the chromosome is compactly coiled, making it visible with appropriate staining and permitting its movement in the cell with minimal entanglement; each organism of a species is normally characterized by the same number of chromosomes in its somatic cells, 46 being the number normally present in humans, including the two (XX or XY) which determine the sex of the organism. In bacterial genetics, a closed circle of double-stranded DNA which contains the genetic material of the cell and is attached to the cell membrane; the bulk of this material forms a compact bacterial nucleus.chromoso´mal .jpg)
Y chromosome,
Y chromosome,
Y chromosome
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Chromosome. (A), Long, threadlike interphase chromatin in nucleus. (B), Giemsa-stained, partially condensed chromatid in late prophase. (C), Giemsa-stained, fully condensed chromatid in metaphase; note that some of the sub-bands visible in late prophase have condensed into single bands. (In B and C, only one of a pair of sister chromatids is shown.)
bivalent chromosome see bivalent (2).
homologous chromosomes a matching pair of chromosomes, one from each parent, with the same gene loci in the same order.
Ph1 chromosome , Philadelphia chromosome an abnormality of chromosome 22, characterized by shortening of its long arms (the missing portion probably translocated to chromosome 9); present in marrow cells of patients with chronic granulocytic leukemia.
ring chromosome a chromosome in which both ends have been lost (deletion) and the two broken ends have reunited to form a ring-shaped figure.
sex chromosomes those associated with sex determination, in mammals constituting an unequal pair, the X and the Y chromosome.
somatic chromosome autosome.
X chromosome a sex chromosome, carried by half the male gametes and all female gametes; female diploid cells have two X chromosomes.
Y chromosome a sex chromosome, carried by half the male gametes and none of the female gametes; male diploid cells have an X and a Y chromosome.
Y chromosome,
a sex chromosome that in humans and many other animals is present only in the male, appearing singly in the normal male. It is present in one half of the male gametes and none of the female gametes, is much smaller than the X chromosome, and has genes associated with triggering the development and differentiation of male characteristics. Compare X chromosome.
Y chromosome,
n a sex chromosome that in humans and many other species is present only in the male, appearing singly in the normal male. It is carried as a sex determinant by one half of the male gametes. None of the female gametes contain a Y chromosome.
yawn,
n an involuntary act of opening the oral cavity wide and taking a deep breath. It tends to occur when a person is bored, drowsy, or depressed and may be accompanied by upper body movements to aid chest expansion.
yaws
n a disease caused by
T. pertenue. It occurs in hot regions; raspberry-like excrescences occur on the hands, face, feet, and external genitalia.
T. pertenue. It occurs in hot regions; raspberry-like excrescences occur on the hands, face, feet, and external genitalia.
Y chromosome
the chromosome which causes the medulla of the embryonic gonad to form a testis. If there is one other chromosome present and it is X the newborn animal will be a fertile male. If there are two other X chromosomes, giving an XXY configuration, it will be a phenotypic male but sterile. Autosomal genes can have the same effect, creating an intersex newborn in an animal with XX chromosomes.
Y chromosome
The sex chromosome of normal ♂. Cf X chromosome.
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