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Disaccharide

A disaccharide is a carbohydrate composed of two monosaccharide units linked by a glycosidic bond formed through a dehydration synthesis reaction. The bond is cleaved by hydrolysis, releasing a molecule of water and yielding two monosaccharides. Disaccharides vary by the identities of their monosaccharide components and by the type of glycosidic linkage.

Common disaccharides include sucrose, lactose, and maltose. Sucrose consists of glucose and fructose and is widely

Biological roles vary: sucrose often serves as a transport sugar in photosynthesizing plants, lactose provides energy

Disaccharides are thus essential dietary carbohydrates, bridging polysaccharides and monosaccharides, with properties and metabolism influenced by

found
in
plants;
lactose
consists
of
galactose
and
glucose
and
is
present
in
milk;
maltose
consists
of
two
glucose
units
and
arises
during
the
digestion
of
starch.
Sucrose
is
non-reducing
because
the
glycosidic
linkage
involves
the
anomeric
carbons
of
both
monosaccharides,
whereas
lactose
and
maltose
are
reducing
sugars
due
to
a
free
anomeric
carbon
in
one
of
their
units.
to
mammals
and
is
a
major
component
of
milk,
and
maltose
appears
during
starch
digestion
and
in
germinating
seeds.
In
digestion,
specific
enzymes
hydrolyze
disaccharides
to
their
monosaccharide
components:
sucrase
(or
invertase)
for
sucrose,
lactase
for
lactose,
and
maltase
for
maltose.
The
resulting
monosaccharides—glucose,
galactose,
and
fructose—are
absorbed
and
enter
glycolysis
or
other
metabolic
pathways
for
energy
production.
the
nature
of
their
constituent
units
and
glycosidic
linkages.