Carbohydrates

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Carbohydrates
Carbohydrates, one of the four major classes of
biomolecules, are aldehyde or ketone compounds
with multiple hydroxyl groups. They function as
energy stores, metabolic intermediates and
important fuels for the body.

• Harini Chandra

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Master Layout (Part 1)
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This animation consists of 3 parts Part 1
Monosaccharides Part 2 Disaccharides
Polysaccharides Part 3 Glycoconjugates
Aldotriose
Asymmetic centre
Ketotriose
2
D-glyceraldehye
L-glyceraldehye
Dihydroxyacetone
3
Enantiomers
Ketohexose
Aldohexose
Aldopentose
4
D-ribose
D-glucose
D-fructose
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Definitions of the componentsPart 1
Monosaccharides
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1. Monosaccharide Monosaccharides comprise the
simplest group of carbohydrates with the
empirical formula (C-H2O)n. They can be either
aldehydes or ketones having two or more hydroxyl
groups. These monosaccharides serve as important
fuel molecules and as the basic building unit for
nucleic acids. 2. Aldotriose The smallest
monosaccharide having an aldehyde group and a
total of 3 carbon atoms is referred to as an
aldotriose. Glyceraldehyde is the simplest
aldotriose. 3. Ketotriose The smallest
monosaccharide that has a ketone group with a
total of 3 carbon atoms is referred to as a
ketotriose. Dihydroxyacetone is the simplest
ketotriose. 4. Asymmetric centre A carbon atom
that has four different groups attached to it in
a tetrahedral arrangement is said to be
asymmetric or chiral and gives rise to the
phenomenon of optical isomerism. All
monosaccharides have multiple asymmetric carbon
atoms, giving rise to 2n isomers for each
monosaccharide, where n refers to the number of
asymmetric centres. 5. Enantiomers Molecules
with a chiral centre have a non-superimposable
mirror image and the two forms of this molecule
are known as enantiomers. They are designated as
D and L or R (rectus) and S (sinister) depending
on the arrangement of groups around the
asymmetric carbon atom. R and S nomenclature is
based on priority of atomic numbers of atoms
directly attached to the central asymmetric
centre.
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Definitions of the componentsPart 1
Monosaccharides
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6. Aldopentose A monosaccharide having an
aldehyde functional group with a total of five
carbon atoms is referred to as an aldopentose.
D-ribose, which is an important component of all
nucleic acids is one such aldopentose. 7.
Aldohexose A monosaccharide having an aldehyde
functional group with a total of six carbon atoms
is referred to as an aldohexose. D-glucose is one
of the most common aldohexoses. 8. Ketohexose A
sugar having a ketone functional group with a
total of six carbon atoms is referred to as a
ketohexose. D-fructose is the most abundant
ketohexose. Ketoses have fewer asymmetric centres
compared to aldoses. 9. Epimers Sugars that
differ in configuration from each other at just
one asymmetric carbon atom, are referred to as
epimers. Glucose and mannose are epimers at C-2
while glucose and galactose are epimers at
C-4. 10. Anomers The aldehyde or ketone
functional groups can react with an alcohol to
form a hemiacetal or ketal. This intramolecular
reaction occurs in sugars, thereby allowing them
to form cyclic structures. These are commonly
represented by means of the Haworths
projections. Upon cyclization, the aldehyde or
ketone carbon becomes C1 and is referred to as
the anomeric carbon atom. The configuration of
groups about the anomeric carbon can result in
either the alpha or beta structures, which are
referred to as anomers.
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Part 1, Step 1
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Monosaccharides optical properties
Mirror
Asymmetric carbon atom
2
L-glyceraldehyde
D-glyceraldehyde
3
Enantiomers
4
Action
Audio Narration
Description of the action
All monosaccharide sugars are optically active
due to the presence of asymmetric carbon atoms.
The simplest aldotriose, D-glyceraldehyde, has
one asymmetric centre giving rise to the D and L
enantiomers, which are mirror images of each
other. A compound will have 2n isomers, where n
is the number of asymmetric centres..
As shown in animation.
(Please redraw all figures.) First show the ball
and stick figure on the left labelled as
D-glyceraldehyde. Next show the appearance of a
silver surface which is the mirror followed by
the reflection of the molecule as shown on the
right.
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Part 1, Step 2
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Monosaccharides aldoses
D-Erythrose
D-Threose
D-Glyceraldehyde
2
D-Ribose
D-Xylose
D-Arabinose
D-Lyxose
3
D-Allose
D-Altrose
D-Glucose
D-Mannose
D-Gulose
D-Iodose
4
D-Talose
D-Galactose
Action
Audio Narration
Description of the action
As shown in animation.
(Please redraw all figures.) First show the
structure on the top labelled D-glyceraldehyde
followed by the arrows on either side and
appearance of next 2 structures. Next, the 2
arrows below each structure must appear
sequentially along with each structure below.
This must continue as shown in animation until
all the structures have been displayed.
Simple D-aldose sugars can have anywhere from
three to seven carbon atoms with an aldehyde
functional group. All the D-sugars have the same
absolute configuration as that of
D-glyceraldehyde at their asymmetric centre that
is farthest away from the carbonyl carbon. The
most commonly observed sugars include D-glucose,
D-mannose and D-galactose.
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Part 1, Step 3
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Monosaccharides Epimers
Differ in configuration at one chiral centre -
Epimers at C-2.
2
3
D-Glucose
D-Mannose
D-Galactose
Differ in configuration at one chiral centre -
Epimers at C-4.
4
Action
Audio Narration
Description of the action
As shown in animation
(Please redraw all figures.) First show the
structure in the centre D-glucose followed by
the structure on the left, D-mannose. The
purple rectangular boxes must then appear, along
with the text box above. Next, the structure on
the right must appear followed by the green
rectangular boxes and the text box at the bottom.
Those sugars that differ in configuration from
each other about only one asymmetric carbon atom
are referred to as epimers. D-Glucose and
D-mannose are epimers at the second carbon atom
while D-glucose and D-galactose are epimers at
the fourth carbon atom. D-mannose and
D-galactose, however are only diastereomers since
they differ in configuration at two asymmetric
centres.
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Part 1, Step 4
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Monosaccharides - ketoses
D-Sorbose
2
D-Xylulose
D-Tagatose
Dihydroxyacetone
D-Erythrulose
D-Fructose
3
D-Psicose
D-Ribulose
4
Action
Audio Narration
Description of the action
As shown in animation.
(Please redraw all figures.) First the left-most
figure must be shown labelled dihydroxyacetone
followed by the right arrow and the next figure
D-erythrulose. Next, the two arrows must appear
with each figure shown in front of the arrow.
This must continue as shown in animation until
all figures are displayed.
Ketoses can be three, four, five or six carbon
sugars with a ketone functional group.
Dihydroxyacetone, the simplest ketose having 3
carbon atoms does not possess an asymmetric
centre. The D configuration is therefore based on
the absolute configuration of D-erythrulose, the
four carbon ketose and is designated based on the
asymmetric centre farthest away from the ketone
group.
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Part 1, Step 5
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ANOMERS
Monosaccharides Haworths projection formula
Anomeric carbon
2
b-D-Glucopyranose
a-D-Glucopyranose
D-Glucose (open chain form)
3
Chair form is more stable due to less steric
hindrance in the axial positions.
Boat form
Chair form
4
Action
Audio Narration
Description of the action
As shown in animation.
(Please redraw all figures.) First show the
figure on top left followed by appearance of
green highlighting boxes and then the arrow. The
structure must bend to take up the shape shown in
the next figure with the highlighted groups
interacting with each other. Next the reaction
arrow must appear and the structures on the right
must be shown. Two arrows must then appear from
the figrst structure b-D-glucopyranose and the
figures below must be shown. The groups shown
must be highlighted with a dotted line appearing
between them in the first figure and a dotted
line with a red cross mark appearing in the
second followed by the callout with text.
The aldehyde or ketone group of monosaccharides
react with the alcohol groups to form
intramolecular hemiacetals or ketals. This gives
rise to stable five or six-membered rings known
as furanose and pyranose respectively. The
functional group carbon atom is designated as C-1
and is known as the anomeric carbon. The
configuration of the groups about the anomeric
carbon gives rise to the alpha and beta
configurations. The chair form of the six
membered pyranose ring is more stable due to
minimal steric hindrance at the axial positions
since they are occupied by small hydrogen atoms.
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Part 1, Step 6
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Monosaccharides Haworths projection formula
ANOMERS
2
b-D-Fructofuranose
a-D-Fructofuranose
3
D-Fructose Open chain form
4
Action
Audio Narration
Description of the action
As shown in animation.
(Please redraw all figures.) First show the
structure on the left with its label followed by
the green highlighting boxes and the curved
arrow. The structure must then curve so as to
appear as shown in the second with the arrow mark
between the highlighted regions as shown. This is
followed by appearance of the arrow and the
structures on the right with their labels.
Although glucose is more stable in the six
membered pyranose configuration, stability of
fructose is greater as a five-membered furanose
ring.
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Part 1, Step 7
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Monosaccharides Reducing nature
2
Fehlings solution (Cu2)
3
Glucose solution
D-glucose
D-gluconic acid
Brown ppt.
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Action
Audio Narration
Description of the action
(Please redraw all figures.) First show the tube
with blue solution on the left with its label.
The inset must appear as being zoomed into and
the first structure must be shown. Then the hand
with the micropipette must be shown and drops
must fall from this into the tube and dissolve on
falling. Once a few drops fall, a brown mass
(precipitate) must appear at the bottom of the
tube. When this happens, the arrow in the
reaction must appear followed by the figure on
the right.
As shown in animation.
A simple test for identifying sugars such as
glucose is by the Fehlings test. The free
aldehyde group provides the sugars with a
reducing nature thereby bringing about reduction
of a solution of cupric ions. This results in an
easily identifiable brown precipitate.
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Part 1, Step 8
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Modified monosaccharides
N-glycosidic bond
O-glycosidic bond
2
Methyl-a-D-glucopyranoside
b-L-fucose (Fuc)
3
Sialic acid (Sia) (N-Acetylneuraminate)
b-D-Acetylgalactosamine (GalNAc)
b-D-Acetylglucosamine (GlcNAc)
4
Action
Audio Narration
Description of the action
As shown in animation.
(Please redraw all figures.) Show each structure
appearing sequentially with the regions
highlighted as shown and their respective labels.
The reactive anomeric carbon atom can be modified
by reaction with alcohols or amines to form
adducts. Reaction of glucose with methanol gives
the corresponding methyl glucopyranoside with the
formation of an O-glycosidic bond. When the
anomeric carbon is linked to an amine via its
nitrogen atom, it results in formation of an
N-glycosidic bond. Several other modified
monosaccharides such as fucose, N-acetyl
glucosamine etc are present which serve various
structural and functional roles.
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Master Layout (Part 2)
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This animation consists of 3 parts Part 1
Monosaccharides Part 2 Disaccharides
Polysaccharides Part 3 Glycoconjugates
Sucrose
2
Glycosidic bond
3
Starch glycogen
4
Cellulose
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Definitions of the componentsPart 2
Disaccharides Polysaccharides
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1. Disaccharide Two monosaccharide units joined
together by means of an O-glycosidic linkage
forms a disaccharide. Three of the most common
disaccharides include maltose, sucrose and
lactose. 2. Polysaccharide Several
monosaccharide units joined together by
glycosidic bonds form a polysaccharide. These
help in maintaining structural integrity and
serve as fuel reserves in organisms. Some of the
most common polysaccharides include starch, the
nutritional reservoir in plants, glycogen the
fuel storage form in animal cells and cellulose,
which is the most important structural elements
in plants. 3. Glycosidic bond The bond formed
by interaction between the hydroxyl group of one
monosaccharide with the hydroxyl group, aldehyde
or ketone group of another monosaccharide, with
the subsequent elimination of water is known as
the glycosidic bond. 4. Hemiacetal The
interaction between an aldehyde or ketone group
with a hydroxyl group with the elimination of
water results in the formation of a hemiacetal or
ketal. In sugars, intramolecular hemiacetals and
ketals are formed by cyclization of the sugar
molecules. 5. Homopolymer When all the
monosaccharide units of a polysaccharide are the
same, it is said to be a homopolymer. The most
common homopolymers are starch and glycogen. 6.
Heteropolymer When the repeating monosaccharide
units of the polysaccharide are different, they
are said to be heteropolymers.
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Definitions of the componentsPart 2
Disaccharides Polysaccharides
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7. Starch The nutritional reserve of plants is
starch, which is composed of two components
amylose and amylopectin. Amylose consists of
linear, unbranched chains of D-glucose residues
linked by a-1,4 glycosidic linkages. Amylopectin,
however, is a branched polymer with an a-1,6
glycosidic linkage present around every 30
residues. Starch is rapidly degraded by the
enzyme amylase. 8. Cellulose Cellulose plays a
major structural role in plants and consists of
linear chains of glucose residues linked together
by b-1,4 glycosidic bonds. These chains formed by
b-linkages have very high tensile strength and
can be digested by the enzyme cellulase, which is
not inherent in mammals. 9. Glycogen Glycogen
is the storage form of glucose in animal cells.
It is structurally similar to starch, with
glucose residues being joined by a-1,4 glycosidic
linkages. Glycogen has more extensive branching
than starch with branch points being observed
around every 10 residues. These allow the
molecules to be stored in a very compact way in
the cells. 10. Chitin Chitin is another
structural polysaccharide that is a homopolymer
of N-acetyl-D-glucosamine residues joined
together by b-1,4 glycosidic linkages. It is
commonly found on the exoskeleton of insects.
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4
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Part 2, Step 1
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Disaccharides - formation
Alcohol
Hemiacetal
2
a-D-glucose
b-D-glucose
H2O
H2O
3
Glycosidic bond
Maltose
a-D-Glucopyranosyl-(1?4)-a-D-glucopyranose
4
Action
Audio Narration
Description of the action
(Please redraw all figures.) First show the
structures on top left top right with the
sign in between. These two structures must move
close to each other and the red highlighted
regions must be removed as H2O and the
resulting structure at the bottom shown with its
labels.
Disaccharides are formed by the condensation
reaction between two monosaccharide units. The
release of a molecule of water results in the
formation of a glycosidic bond between the two
residues. Shown in this example is the formation
of maltose, a disaccharide that is composed of
two units of glucose linked by an a-1?4
glycosidic bond. Maltose is hydrolyzed into its
individual units by the enzyme maltase.
As shown in animation.
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Part 2, Step 2
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Common disaccharides
2
Sucrose
a-D-glucopyranosyl-(1?2)-b-D-fructofuranose
3
Lactose
b-D-Galactopyranosyl-(1?4)-a-D-glucopyranose
4
Action
Audio Narration
Description of the action
As shown in animation.
(Please redraw all figures.) Show the sequential
appearance of the figures above as shown.
Table sugar or sucrose is a disaccharide composed
of one unit of glucose and one of fructose linked
by a b-1?2 bond. It is a non-reducing sugar since
the aldehyde group of glucose and ketone group of
fructose are involved in formation of the
glycosidic linkage. It can be cleaved by the
enzyme sucrase. Lactose, the sugar component of
milk, is made up of one unit of galactose and one
of glucose linked by an a-1?4 linkage. It can be
cleaved by the enzyme lactase, also known as
b-galactosidase.
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Part 2, Step 3
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Polysaccharides Starch, a homopolymer of
D-glucose residues
Reducing end
Non-reducing end
a-1, 4-glycosidic linkage
Starch granules
2
Amylose
3
a-(1?6) branch point
Branch
Main chain
Amylopectin
4
Action
Audio Narration
Description of the action
Starch granules, which form the major nutritional
reserve of plants, are composed of two components
amylose and amylopectin. Amylose consists of
linear, unbranched chains of D-glucose residues
linked by a-1,4 glycosidic linkages. Amylopectin,
however, is a branched polymer with an a-1,6
glycosidic linkage present around every 30
residues. Starch is rapidly degraded by the
enzyme amylase.
As shown in animation.
(Please redraw all figures.) First show the
figure on the left with the label for starch
granules. This region must then be zoomed into
and the structures on the right must be shown.
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Part 2, Step 4
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Glycogen is a highly branched molecule with
branch points every 10 residues.
Polysaccharides Glycogen, a homopolysaccharide
of D-glucose residues
a-1, 4-glycosidic linkage
Glycogen granules
2
3
a-(1?6) branch point
4
Action
Audio Narration
Description of the action
Glycogen is the storage form of glucose in animal
cells. It is structurally similar to start with
glucose residues being joined by a-1,4 glycosidic
linkages. Glycogen has more extensive branching
than starch with branch points being observed
around every 10 residues. These allow the
molecules to be stored in a very compact way in
the cells.
As shown in animation.
(Please redraw all figures.) First show the
figure on the left with the label glycogen
granules. This must then be zoomed into and the
structure on the right must be shown. This is
followed by appearance of the brown text star on
the top.
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Part 2, Step 5
1
Polysaccharides Cellulose Chitin
2
N-acetyl-D-glucosamine residues
b-1, 4-glycosidic linkage
Cellulose
3
Chitin
b-(1?4) linkage
4
Action
Audio Narration
Description of the action
As shown in animation.
(Please redraw all figures.) Show the sequential
appearance of the two structures with their
labels as depicted.
Cellulose plays a major structural role in plants
and consists of linear chains of glucose residues
linked together by b-1,4 glycosidic bonds. These
chains formed by b-linkages have very high
tensile strength and can be digested by the
enzyme cellulase, which is not inherent in
mammals.Chitin is another structural
polysaccharide that is a homopolymer of
N-acetyl-D-glucosamine residues joined together
by b-1,4 glycosidic linkages. It is commonly
found on the exoskeleton of insects.
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Master Layout (Part 3)
1
This animation consists of 3 parts Part 1
Monosaccharides Part 2 Disaccharides
Polysaccharides Part 3 Glycoconjugates
Proteoglycan structure
Glycolipid
2
Sugar residues
Glycosidic bonds in glycoproteins
3
Asn
Ser
Lipid
4
O-linked GalNAc
N-linked GlcNAc
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Definitions of the componentsPart 3
Glycoconjugates
1
1. Glycosaminoglycan Glycosaminoglycans are
heteropolysaccharide repeating units found on
animal cell surfaces and in the extracellular
matrix. They are composed of disaccharide units
that contain a derivative of an amino sugar and
at least one of the sugars in the unit has a
negatively charged carboxylate or sulphate
group. 2. Proteoglycan These are structural
elements that are composed of glycosaminoglyan
units linked to proteins. The proteoglycan,
aggrecan, is a major component of cartilage along
with the protein, collagen, where it serves as a
shock absorber. Degradation of aggrecan and
collagen can lead to osteoarthritis. 3.
Glycoprotein Carbohydrate groups are often
covalently attached to proteins to form
glycoproteins. The sugar residues are typically
attached to the amide nitrogen atom of the
aspargine side chain or to the oxygen atom of the
serine or threonine side chain. These
glycoproteins are components of cell membranes
and have a variety of functions in cell adhesion
processes. 4. Glycolipid Carbohydrate moieties
can also be covalently linked with various
lipids. Glycolipids are membrane components
bearing a hydrophilic head group and a
hydrophobic lipid tail. 5. Glycosyl
transferase These are a specific class of
enzymes that are responsible for the transfer or
sugar residues onto other substrates. They
transfer the sugar in its activated state such as
UDP-glucose to other molecules such as other
monosaccharides, polysaccharides or amino acid
side chains of proteins.
2
3
4
5
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Part 3, Step 1
1
2
Chondroitin-6-sulphate
Keratan sulphate
Glycosaminoglycans
3
Heparin
Hyaluronate
Dermatan sulphate
4
Action
Audio Narration
Description of the action
As shown in animation.
(Please redraw all figures.) First show the
heading in the centre followed by sequential
appearance of all the structures with their
labels as depicted in animation.
Glycosaminoglycans are heteropolysaccharide
components of extracellular matrix spaces along
with other fibrous proteins. They are linear
polymers that are composed of disaccharide
repeating units of which one residue is always a
derivative of an amino sugar such as N-acetyl
glucosamine or N-acetyl galactosamine. They also
contain a negatively charged sulphate or
carboxylate group.Common glycosaminoglycans
include chondrotin sulphate, hyaluronate, heparin
etc.
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Part 3, Step 2
1
Glycosyl transferase reaction
2
Substrate to be glycosylated
UDP-glucose
Glycosyl transferase
3
Glycosylated substrate
UDP
4
Action
Audio Narration
Description of the action
As shown in animation.
(Please redraw all figures.) First show the
structures on top with their labels. Next show
the arrow mark with the label. The pink structure
must then be broken from the remaining black
structure at the position indicated by the dotted
line and the blue X must be attached there in
place of the O as shown in the figure below.
And the blue H must be attached to the red O
linked to remaining black structure.
Glycosyl transferases are specific enzymes that
bring about transfer of activated sugar residues
onto other substrates. The activated sugar linked
to a nucleotide moiety such as UDP is cleaved and
covalently linked with the substrate which could
either be another monosaccharide unit, a
polysaccharide or the serine or aspargine side
chains of proteins.
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Part 3, Step 3
1
Cartilage is made of the proteoglycan, aggrecan,
which serves as a shock absorber.
Proteoglycan structure
2
Protein
Glycosaminoglycan
3
4
Action
Audio Narration
Description of the action
As shown in animation.
Glycosaminoglycans can be linked to proteins to
form various proteoglycans. These molecules have
a variety of functions in tissue organization,
development of specialized tissues and for
modulation of ligand interactions with cell
surface receptors. Aggrecan is a proteoglycan
aggregate consisting of many core proteins bound
to a single hyaluronate molecules they serve as
shock absorbers in cartilage.
(Please redraw all figures.) First show the
colored rectangular structure with all the
labels. Next show the appearance of the vertical
chain on the side as depicted in animation
followed by appearance of the speech bubble with
text.
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Part 3, Step 4
1
Glycoproteins
Blood groups
Ser
Asn
2
3
O-linked GalNAc
N-linked GlcNAc
O antigen
A antigen
B antigen
4
Action
Audio Narration
Description of the action
As shown in animation.
Carbohydrate groups are often covalently attached
to proteins to form glycoproteins. The sugar
residues are typically attached to the amide
nitrogen atom of the aspargine side chain or to
the oxygen atom of the serine or threonine side
chain. These glycoproteins are components of cell
membranes and have a variety of functions in cell
adhesion processes. The ABO blood groups arise
due to differing carbohydrate structures on the
surface of the blood cells.
(Please redraw all figures.) First show the two
structures on the left appearing one after the
other. Then show the figures on the right with
each structure appearing sequentially as depicted
in the animation.
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Part 3, Step 5
1
Glycolipids
Lipopolysaccharide
Sugar residues
2
3
Bacterial cell
Cell membrane
Lipid
4
Action
Audio Narration
Description of the action
As shown in animation.
(Please redraw all figures.) First show the
bacterial cell on the left. The region marked
in red must be zoomed into and the next structure
must be shown. The red circle must then appear
with its label on this structure, which must be
further zoomed into to show the rightmost
structure.
Carbohydrate moieties can also be covalently
linked with various lipids. Glycolipids are
membrane components bearing a hydrophilic head
group and a hydrophobic lipid tail.
Lipopolysaccharides are a predominant feature on
the outer membrane of gram negative bacteria,
which consist of fatty acid chains bound to sugar
residues.
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Interactivity option 1Step No 1
1
A common chemical test to detect the presence of
starch is to treat it with a solution of iodine.
The reaction is believed to occur due to charge
transfer between iodine molecules that fit inside
the amylose coils and the glucose residues of
amylose. Starche that contain less amylose
content do not give a prominent colour change.
Drag and drop the iodine molecules into the
crevices of the amylose helix shown to view the
reaction.
2
I3-
I3-
3
Amylose
Blue colour indicating presence of starch
I3-
I3-
I3-
4
Boundary/limits
Interacativity Type Options
Results
The user must drag and drop the round structures
into the curved spaces to view the reaction as
shown in the animation. Once the user drags all
the round figures into the crevices, the colour
of the chain must turn blue as shown in the
figure on the right.
Drag drop.
(Please redraw all figures.) User must drag
drop the round structures into the curved spaces.
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Questionnaire
1

• 1. Which of the following monosaccharides does
  not have an asymmetric centre?
• Answers a) D-Glyceraldehyde b) D-Erythrulose
  c) Dihydroxyacetone d)? D-Ribulose
• 2. Which of the following sugars is a C-2 epimer
  of glucose?
• Answers a) Galactose b) Mannose c) Iodose
  d)? Allose
• 3. Chitin is a homopolysaccharide of which of the
  following monosaccharide residues?
• Answers a) N-acetyl-D-glucosamine b)
  a-D-glucose c) b-D-glucose d)? D-fructose
• 4. Lactose is a disaccharide composed of which of
  these monosaccharide units?
• Answers a) 2 units of Glucose b) Glucose
  fructose c) 2 units of Galactose d)? Glucose
  galactose
• 5. The glycosaminoglycan found in aggrecan is?
• Answers a) Chondroitin-6-sulphate b) Heparin
  c) Keratan sulphate d)? Hyaluronate

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Links for further reading

• Books
• Biochemistry by Stryer et al., 6th edition
• Biochemistry by A.L.Lehninger et al., 4th edition
• Biochemistry by Voet Voet, 3rd edition