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Chemicals or molecules present in living
organisms
Compounds of carbon
 The chemistry of living organisms is organized
around carbon
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Building blocks
Makes up biomolecules
Carbohydrates – sugar
Proteins – amino acid
Nucleic acid – nucleotides
Lipids – fatty acid and glycerol
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Carbohydrates – glycosidic bond
Proteins – peptide bond
Lipids – ester bond
Nucleic acids – phosphodiester linkages
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Most abundant organic molecules in nature
Defined as organic substances having C, H
and O
 Wherein H and O are in the ratio of 2:1
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Most abundant source of energy
Precursors for many organic compounds
Present as glycoproteins and glycolipids in
the cell membrane and functions for cell
growth and fertilization
Present as structural components like
cellulose in plants, exoskeleton of some
insects, cell wall of microorganisms
Storage form of energy (glycogen) to meet
the energy demands of the body
Carbohydrates
Monosaccharide
Oligosaccharide
Polysaccharide
BASED ON THE NUMBER OF
C-ATOMS
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Triose (C3H6O3)
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Aldose
 Functional group is aldehyde
Tetrose (C4H8O4)
 e.g. Glyceraldehyde
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Ketose
Pentose (C5H10O5)
 Functional group is ketone
 Arabinose
 e.g. Dihydroxyacetone
Hexose (C6H12O6)
 Glucose
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 Glyceraldehyde
 Erythrose
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BASED ON FUNCTIONAL
GROUPS
Heptose (C7H14O7)
 Glucoheptose
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Formed by condensation of 2-9
monosaccharides
Based on the number of monosaccharide
molecules:
 Disaccharides – smallest and most common
 Trisaccharides
 Tetrasaccharides
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Consists of 2 monosaccharide units held
together by a glycosidic bond
Maltose
 Malt sugar
 Made up of two glucose molecules
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Lactose
 Milk sugar
 Made up of glucose and galactose
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Sucrose
 Cane sugar
 Made up of glucose and fructose
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Also called as glycans
Made up of repeating units of
monosaccharides held by glycosidic bonds
Ideal as storage and as structural
components
2 types: homoglycans and heteroglycans
HOMOGLYCANS
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Made up of only 1 type of
monosaccharide
monomers
E.g. starch, glycogen,
cellulose
Glucan (made up of
glucose)
Fructan (made up of
fructose)
Galactan (made up of
galactose)
HETEROGLYCANS
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Made up to 2 or more
types of monosaccharides
E.g. hyaluronic acid, agar,
chitin, peptidoglycan
STORAGE POLYSACCHARIDES
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Starch
STRUCTURAL
POLYSACCHARIDES
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 Carbohydrate reserve of plants
 Most important dietary source for
 Occurs exclusively in plants
 Most abundant organic substance
 Predominant constituent of plant
animals
 Amylose + Amylopectin
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Glycogen
Cellulose
cell wall
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Chitin
 Carbohydrate reserve of animals;
 Second most abundant organic
referrred to as animal starch
 High concentration in liver,
muscles and brain
 Glucose is the repeating unit
substance
 Found in exoskeleton of some
invertebrates like insects and
crustaceans
 Provides strength and elasticity
 Becomes hard due to calcium
carbonate
Inulin
 Polymer of fructose
 Easily soluble in water
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Most abundant organic molecules of the
living system
Form about 50% of the dry weight of the cell
Most important for the architecture and
functioning of the cell
Monomer – amino acids
Collagen – most abundant animal protein
Rubisco – most abundant plant protein
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Group of organic compounds having 2
functional groups (-NH2) and (–COOH)
(-NH2) group is basic whereas (-COOH) is
acidic
R- can be H in glycine, CH3 in alanine,
hydroxymethyl in serine, in others it can be a
hydrocarbon chain or a cyclic group
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4 basic structural levels are assigned to
proteins
 Primary
 Secondary
 Tertiary
 Quaternary
Primary – describes the unique order in which
amino acids are linked together to form a
protein
 Secondary – refers to the coiling or folding of a
polypeptide chain that gives the protein its 3-D
shape
 Tertiary – refers to the comprehensive 3-D
structure of the polypeptide chain of a protein
 Quaternary – refers to the structure of a protein
macromolecule formed by interactions between
multiple polypeptide chains
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Structural
proteins
Enzymatic
proteins
Transport
proteins
Hormonal
proteins
Functional
Classification
Contractile
proteins
Storage
proteins
Genetic
proteins
Defense
proteins
Receptor
proteins
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Simple proteins
 Composed only of amino acid residues
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Conjugated proteins
 Along with amino acids, there is a non-protein
prosthetic group
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Derived proteins
 Denatured or degraded products
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Chief concentrated storage form of energy
forming about 3.5% of the cell content
Hydrophobic (“water-fearing”) or insoluble in
water, because they are
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Concentrated fuel reserve of the body
Constituents of membrane structure and
regulate membrane permeability
Serve as source of fat soluble vitamins
Important cellular metabolic regulators
Protect the internal organs and serve as
insulating materials
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Made up of fatty acids and glycerol
Fatty acids may be saturated or unsaturated
 Saturated fatty acids – solid at room temp
 Unsaturated fatty acids – liquid at room temp
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Monomer - nucleotides
2 types:
 DNA (deoxyribonucleic acid)
 RNA (ribonucleic acid)
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Storage for genetic information
Sequence of nitrogenous bases in DNA
determines the protein development in new
cells
DNA controls the synthesis of RNA
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The purines adenine (A) and guanine (G) and
the pyrimidine cytosine (C) are present in
both DNA and RNA. The pyrimidine thymine
(T) present in DNA is replaced by the
pyrimidine uracil (U) in RNA.