monogamy The practice of having one mate at a
time, lifelong pair bonding.
monogyny Insocial insects, having one queen per
nest, as with ants.
monohybrid cross A cross that involves two parents
that differ in only one trait.
monomer Abasic building block or small organic
molecule that makes up a polymer when combined
with identical or similar monomers through polymer-
ization. Polymers are important substances in organ-
isms, e.g., proteins are polymers.
mono-oxygenase An ENZYME that catalyzes the
INSERTIONof one atom of oxygen, derived from O 2 ,
into an aromatic or aliphatic compound. The reaction
is coupled to the oxidation of a coSUBSTRATEsuch as
NAD(P)H or 2-oxoglutarate.
monophyletic Refers to a group of organisms that
includes the common ancestor and all descendants of
this common ancestor. The group of organisms is also
called a clade.
monosaccharide A simple sugar such as fructose or
glucose that cannot be decomposed by hydrolysis; col-
orless crystalline substances with a sweet taste that
have the same general formula, CnH2nOn. They are
classified by size according to the number of carbon
atoms in the chain, such as dioses, two carbon-ring
backbone; trioses, three carbon-ring backbone; heptose
with seven carbon-ring backbone, etc. Further classi-
fied as aldoses (when carbonyl group is an aldehyde) or
ketoses (contains a carbonyl [keto] group in its
straight-chain form).
monotreme An egg-laying mammal that feeds its
young with milk once hatched. Only two forms
exist in the world, and both live in Australia: the
short-beaked echidna (the spiny anteater) and the
duck-billed platypus.montane A biological zone of altitude found in
mountains, above the tree line, and usually based on at
least 500 m (1,600 ft.) elevation.Morgan, Thomas Hunt(1866–1945) American
Zoologist Thomas Hunt Morgan was born on Septem-
ber 25, 1866, in Lexington, Kentucky, to Charlton Hunt
Morgan. He received a B.S. at the University of Kentucky
in 1886 and completed postgraduate work at Johns Hop-
kins University, where he studied morphology with W. K.
Brooks and physiology with H. Newell Martin.
In 1890 he obtained a Ph.D. degree at Johns Hop-
kins University for his work on the evolutionary rela-
tionships of pycnogonids (sea spiders).
In 1891 he became associate professor of biology
at Bryn Mawr College for women, Pennsylvania, where
he stayed until 1904, then becoming professor of
experimental zoology at Columbia University, New
York. He remained there until 1928, when he was
appointed professor of biology and director of the G.
Kerckhoff Laboratories at the California Institute of
Technology, at Pasadena. Here he remained until 1945.
During his later years he had his private laboratory at
Corona del Mar, California.
Morgan’s early work on genetic linkage with
Drosophila melanogaster(the fruit fly) was put forward
as a theoryof the linear arrangement of the genes in the
chromosomes. He described the phenomena of linkage
and crossing over, which he explained in Mechanism of
Mendelian Heredity(1915). He was the first to show
that variation derives from numerous small mutations.
His work also established the use of drosophila as a
model for genetic research gene-mapping efforts. For his
discoveries concerning the role played by the chromo-
some in heredity, he was awarded the Nobel Prize in- Morgan is considered a cofounder, along with
William Bateson, of modern genetics.
He also wrote several important genetics books:
Heredity and Sex(1913), The Physical Basis of Heredity
(1919), Embryology and Genetics(1924), Evolution and
Genetics(1925), The Theoryof the Gene(1926), Exper-
imental Embryology(1927), and The Scientific Basis of
Evolution(1935). He died on December 4, 1945.
226 monogamy