Complex Carbohydrates: Starch, Glycogen, and Cellulose Analysis

This assignment provides a comprehensive overview of three essential complex carbohydrates: starch, glycogen, and cellulose. It details the molecular structures of each, including the components of starch (amylose and amylopectin), the branching patterns of glycogen, and the linear arrangement of cellulose. The assignment explains the functions of each polysaccharide, such as starch's role as a plant energy reserve, glycogen's function as an animal energy reserve, and cellulose's role in plant cell walls. Furthermore, it highlights the key differences between these molecules, including their glucose unit linkages and resulting three-dimensional structures. The assignment also includes references to relevant scientific literature, offering a well-rounded understanding of these vital biomolecules. This resource is available on Desklib, offering students valuable insights into carbohydrate biology.

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STRUCTURE AND FUNCTION OF STARCH
[name of the student
What is starch?
• Starch is an abundantly found biomolecule
and constitutes the carbohydrate reserves in
plants as tubers and endosperms of seeds.
• The structural formula of starch is
(C6H10O5)n..
• The structural component consists of
amylose, the liner polymer and amylopectin,
the branched form.
Amylose
• Amylose constitutes 20-30% of the starch
biomolecule.
• Amylose molecules are liner polymers of
500-20,000 α-(14)-D-glucose units.
• A single helix of amylose contains hydrogen-
bonding on outer surface of the helical
structure with the oxygen ring pointing
inwards. The aligned chains can then
develop into double-stranded crystallites
which can resist amylases.
Amylopectin
• Amylopectin constitutes about 70-80% of the
starch biomolecule.
• Amylopectin is formed by the branching of
amylose-type α-(14)-D-glucose units.
• There are higher unbranched chains on the
outside, called A-chains compared to the
branched chains on the inside, called B-
chains. A single C-chain is present which
contains reducing group.
Structure of starch
.
Differences
Starch Vs cellulose
• Both starch and cellulose are polymers of glucose
but differ in structures. While starch consists of α-
glucose units, cellulose consists of β-glucose units,
which cause huge differences in their 3-D structures.
Starch Vs Glycogen
• Starch is made up of two types of molecules while
glycogen only constitutes a single type of molecule.
• Glycogen is the reserves of animals while starch is
the reserves of in plants.
Functions
References
• Guo, P., Li, Y., An, J., Shen, S. and Dou, H.,
2019. Study on structure-function of starch
by asymmetrical flow field-flow fractionation
coupled with multiple detectors: A
review. Carbohydrate polymers, p.115330.
• Starch is used as a water binder, thickener,
gelling agent and emulsion stabilizer (Guo et
al. 2019).
• The extensive conformation of amylose
makes the starch a good hydrocolloid and
functional as films and gels.
• In industries, starch is used to produce
ethanol for beer manufacture by converting it
into sugars by fermentation or malting.
Amylose
Amylopectin

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STRUCTURE AND FUNCTION OF GLYCOGEN
What is glycogen?
• Glycogen is the fundamental form of energy
reserves in animals.
• Glycogen can be produced by certain fungi
as well.
• Excess glucose is stored in animals in the
form of glycogen.
• Glycogen has no effect on the osmotic
balance of animal cells.
Structure of Glycogen
• Glycogen resembles amylopectin in its
structure with a higher count of side chains.
• A typical glycogen molecule consists of
about 30,000 repeating sub-units of glucose.
• These excess branches enable the rapid
release of the stored glucose.
• The high number of branches make the
structure of the glycogen molecule very
compact (Wang et al. 2019).
Glycogen molecule
Structure of glycogen
Glycogen Vs Cellulose
• Cellulose is present only in plant cells whereas
glycogen is present in animals and non-
chlorophyll containing plants such as fungi.
• Cellulose comprises of β-glycosidic bonds
whereas glycogen comprises of α-glycosidic
bonds between monomers.
• Cellulose are linear, long and unbranched
chains while glycogen molecules are short,
highly branched molecules.
Functions of glycogen
• Glycogen maintains the levels of blood
glucose.
• Glycogen stores chemical energy in animals.
• Muscle glycogen provides ATP during
muscle contraction.
• Liver glycogen helps in maintaining
homeostasis.
References
• Wang, L., Liu, Q., Tan, X., Wang, Z., Wang,
M., Wise, M.J., Li, C., Ma, C., Li, E., Deng,
B. and Du, Y., 2019. Molecular structure of
glycogen in Escherichia
coli. Biomacromolecules, 20(7), pp.2821-
2829.

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STRUCTURE AND FUNCTION OF CELLULOSE
What is cellulose?
• The chemical formula of cellulose is
(C6H10O5)n.
• This polysaccharide consists of a linear
chain of repeated units β(1→4) linked D-
glucose.
• It is a major constituent of the primary cell
wall of green plants.
Comparison
Cellulose structure
Structure of cellulose
• The zwitter-ionic structure of cellulose
consists of a long chain of about 500 glucose
units (Tsuchiya et al. 2020).
• Most of the polysaccharide chains are aligned
in parallel rows forming cellulose microfibrils.
• Each polysaccharide chain is bound together
by hydrogen bonds in the microfibrils.
• The microfibrils are bundled together forming
macrofibrils
Function of cellulose
• Cellulose is extensively used to produce
paper and paperboard.
• It is also used to manufacture rayon and
cellophane.
• Cellulose is also used in industries for cotton
and wood pulp.
• Bacteria produce cellulose to make biofilms.
References
Β-glucose monomer
↓
Tsuchiya, K., Yilmaz, N., Miyamoto, T.,
Masunaga, H. and Numata, K., 2020.
Zwitterionic polypeptides: Chemoenzymatic
synthesis and loosening function for cellulose
crystals. Biomacromolecules.