Carbohydrates Flashcards
a major source of energy
from our diet
composed of the elements C,
H and O
also called saccharides,
which means “sugars”
Carbohydrates
simplest carbohydrates
3 to 6 carbon atoms (typically)
a carbonyl group (aldehyde or ketone)
several hydroxyl groups
Monosaccharides
are monosaccharides with an aldehyde group
with many hydroxyl (—OH)
groups
Aldoses
are monosaccharides with a ketone group
with many hydroxyl (—OH)
groups
Ketoses
is used to represent carbohydrates
places the most oxidized group at the top
shows chiral carbons as the intersection of vertical and horizontal lines
Fischer projection
found in fruits, corn syrup,
and honey
an aldohexose with the
formula C6H12O6
known as blood sugar in
the body
the monosaccharide in
polymers of starch,
cellulose, and glycogen
D-glucose
measures blood glucose for
several hours after ingesting glucose
Glucose tolerance test
formula C6H12O6
not found free in nature
obtained from lactose, a
disaccharide
a similar structure to
glucose except for the
—OH on C4
D-galactose
is a ketohexose with
the formula C6H12O6
is the sweetest
carbohydrate
is found in fruit
juices and honey
is converted to
glucose in the body
D-fructose
is a aldopentose
Components of a
variety of complex
molecules such as
RNA and DNA,
Energy-rich
compounds like ATP
D-ribose
are the prevalent form of monosaccharides with 5 or 6 carbon atoms
form when the hydroxyl group on carbon 5 (C5)
reacts with the aldehyde or ketone group
Haworth structures
are cyclic hemiacetals
form when the C═O group and the
—OH are part of the same
molecule
of hexoses form when the —OH
on C5 reacts with a C═O group
of a D-isomer place the —CH2OH
of C6 above the ring
Haworth structures
is a ketohexose
forms Haworth structures when the —OH on C5 bonds to the C═O on C2
Fructose
are monosaccharides with a carbonyl group that oxidizes to give a carboxylic acid
undergo reaction with Benedict’s reagent (Cu2+) to give the corresponding carboxylic acid
include the monosaccharides glucose, galactose, and fructose
Reducing sugars
sugar alcohols called
alditols
consists of two monosaccharides
Disaccharide
a disaccharide is also known as malt sugar
composed of two D-glucose molecules
obtained from the hydrolysis of starch
linked by an α-1,4-glycosidic bond between the
α —OH on C1 of the first glucose and —OH on C4 of the second glucose
used in cereals, candies, and brewing
found in both the α- and β- forms
Maltose
is a disaccharide of β-D-galactose and α- or
β-D-glucose
contains a β-1,4-glycosidic bond
is found in milk and milk products
is found in both the α- and β- forms
Lactose
is obtained from sugar cane and sugar beets
consists of α-D-glucose and β-D-fructose
has an α,β-1,2-glycosidic bond
Sucrose
differ in sweetness
are compared to
sucrose (table sugar),
which is assigned a
value of 100
Sweeteners
are polymers of D-glucose
include amylose and
amylopectin, starches made of
α-D-glucose
include glycogen (animal starch
in muscle), which is made of
α-D-glucose
include cellulose (plants and
wood), which is made of
β-D-glucose
Polysaccharides
a polymer of α-D-glucose molecules
linked by α-1,4 glycosidic bonds
a continuous (unbranched) chain
Amylose
is a polymer of α-D-glucose molecules
is a branched-chain polysaccharide
has α-1,4-glycosidic bonds between the glucose units
has α-1,6 bonds to branches
Amylopectin
is the polysaccharide that stores α-D-glucose
in muscle
is similar to amylopectin but is more highly
branched
Glycogen
is a polysaccharide of glucose units in unbranched chains
has β-1,4-glycosidic bonds
cannot be digested by humans because humans cannot break down β-1,4-glycosidic bonds
Cellulose
