Webster's New World Medical Dictionary

Christmas disease
See 
hemophilia B.
chromatid
One of the two daughter strands cre-
ated by the lengthwise division of the chromosome.
The two chromatids are at first joined together by a
centromere, and then they separate, with each chro-
matid becoming a chromosome.
chromatography, gas
An automated technique
for separating mixtures of substances in which the
mixture to be analyzed is vaporized and carried by
83
chromatography, gas
04_189283 ch03.qxp 4/18/08 10:14 PM Page 83
http://www.rashidislamiccenter.com
http://www.allofislam.com/

---

an inert gas through a special column and thence to
a detection device.
chromatopsia
Colored vision. A condition in
which objects appear abnormally colored to the
viewer.
chromosome
A carrier of genetic information
that is visible under an ordinary light microscope.
Each human chromosome has two arms, the p
(short) arm and the q (long) arm. These arms are
separated from each other only by the centromere,
which is the point at which the chromosome is
attached to the spindle during cell division. The 3
billion base pairs in the human genome are organ-
ized into 24 chromosomes. All genes are arranged
linearly along the chromosomes. Generally the
nucleus of a human cell contains two sets of chro-
mosomes—one set given by each parent. Each set
has 23 single chromosomes: 22 autosomes and an
X or a Y sex chromosome. (A normal female has a
pair of X chromosomes; a male has an X and Y
pair.) A chromosome contains roughly equal parts
of protein and DNA. The chromosomal DNA con-
tains an average of 150 million nucleotide building
blocks, called bases. DNA molecules are among the
largest molecules now known.