The document discusses the chemical basis of animal life. It explains that animals are made up of molecules composed of atoms bonded together. Carbon is a key element in organic compounds due to its unique properties. Carbohydrates and lipids provide most animals with energy, while proteins, nucleotides, and nucleic acids give structure, function, information storage, energy transfer, and genetic regulation. The main biomolecules that make up animal life are then described in more detail, including carbohydrates, lipids, and proteins.
1. The Chemical Basis of Animal Life
Naveed Akhtar
Assistant Professor of Zoology
Punjab Higher Education Department
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2. Concepts
Animals are made up molecules which are collection of
atoms bounded to one another
Carbon is the key element of organic compound because it
has unique physical and chemical characteristics
Carbohydrate and lipids are main compounds of energy
for most animals
Protein, nucleotides and nucleic acids provide basic
structure, function, information storage, energy transfer
and genetic regulation for animal life
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3. The Molecules of Life
BIOMOLECULES
Biomolecules are molecules that occur naturally in
living organisms.
Biomolecules include macromolecules like
proteins, carbohydrates, lipids and nucleic acids.
It also includes small molecules like primary and
secondary metabolites and natural products.
Biomolecules consists mainly of carbon and
hydrogen with nitrogen, oxygen, sulphur, and
phosphorus.
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6. Carbohydrates
Carbohydrates are compounds of carbon, hydrogen, and
oxygen
They are usually present in the ratio of 1 C: 2 H
Hydrated Carbons
The general formula Cx(H2O)y is commonly used to
represent many carbohydrates, which means “watered
carbon.”
Carbohydrates are probably the most abundant and
widespread organic substances in nature, and they are
essential constituents of all living things
A polyhydroxyaldehyde or polyhydroxyketone, or a
substance that gives these compounds on hydrolysis
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7. Functions of Carbohydrates
1.Source of Energy:
Carbohydrates function in protoplasm mainly as structural
elements and as a source of chemical energy
55-60% of our energy comes from carbohydrates
Glucose is the most important of these energy storing
carbohydrates.
Living organisms use carbohydrates as accessible energy to
fuel cellular reactions.
They are the most abundant dietary source of energy
(4kcal/gram) for all living beings.
Carbohydrates along with being the chief energy source, in
many animals, are instant sources of energy. Glucose is
broken down by glycolysis/ Kreb’s cycle to yield ATP.
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8. Serve as energy stores, fuels, and metabolic
intermediates. It is stored as glycogen in animals and
starch in plants.
Stored carbohydrates act as an energy source instead
of proteins.
2.Structural Components
They form structural and protective components, like
in the cell wall of plants and microorganisms.
Structural elements in the cell walls of bacteria
(peptidoglycan or murein), plants (cellulose) and
animals (chitin).
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9. Carbohydrates are intermediates in the biosynthesis of
fats and proteins.
Carbohydrates aid in the regulation of nerve tissue and
is the energy source for the brain.
Carbohydrates get associated with lipids and proteins
to form surface antigens, receptor molecules, vitamins,
and antibiotics.
Formation of the structural framework of RNA and
DNA (ribonucleic acid and deoxyribonucleic acid).
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10. They are linked to many proteins and lipids. Such
linked carbohydrates are important in cell-cell
communication and in interactions between cells and
other elements in the cellular environment.
In animals, they are an important constituent of
connective tissues.
Carbohydrates that are rich in fiber content help to
prevent constipation.
Also, they help in the modulation of the immune
system
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13. (Types of Carbohydrates)
Carbohydrates are usually categorized into the
following three classes;
1. Monosaccharides
2. Oligosaccharides
3. Polysaccharides
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15. Monosaccharides
Simplest group of carbohydrates and often called simple sugars since
they cannot be further hydrolyzed.
Colorless, crystalline solid which are soluble in water and insoluble in a
non-polar solvent.
These are compound which possesses a free aldehyde or ketone
group.
Sweet in taste
They are reducing sugars
The general formula is Cn(H2O)nor CnH2nOn.
They are classified according to the number of carbon atoms they
contain and also on the basis of the functional group present.
The monosaccharides thus with 3,4,5,6,7… carbons are called trioses,
tetroses, pentoses, hexoses, heptoses, etc., and also as aldoses or
ketoses depending upon whether they contain aldehyde or ketone
group.
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22. Monosaccharides in solution are in equilibrium
between the open-chain and ring forms, and exist
primarily in the ring form
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23. Difference between Reducing and
Non reducing Sugars
Reducing Sugars Non Reducing Sugars
Reducing sugars are carbohydrates that
can act as reducing agents due to
presence of free aldehyde or ketone
group
Reducing sugars are carbohydrates that
can not act as reducing agents due to
absence of free aldehyde or ketone
group
Good Reducing Agents Non Reducing Agents
Give positive test towards the Benedict
Test
Give positive test towards the Benedict
Test
All monosaccharides and some
disaccharides including maltose ,
lactose, cellobiose
Most oligosaccharides and all
polysaccharides
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24. Oligosaccharides
An oligosaccharide (Oligo; "a few“) contains 2-10
monosaccharides units
Joined together by as pacific bond call Glycosidic Bond or
Glycosidic Linkage
On hydrolysis, give two to ten monosaccharides
They are subdivided into different catagories based upon
number of monosaccharides produced on hydrolysis
Disacchardies
Trisacchardies
Tetrasacchardies
Pentasacchardies
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26. Disacchardies
Two monosaccharides can combine to form a disaccharide
(di, two) by removing a molecule of water (dehydration
synthesis)
Disaccharides all have the same molecular formula,
C12H22O11
Compounds with the same molecular formula but different
structure are isomers.
Examples:
Sucrose = Glucose +Fructose
Maltose= Glucose Glucose
Lactose= Glucose+Glactose
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27. Sucrose
Sucrose (table sugar) is a disaccharide formed by
linking a molecule of glucose to a molecule of fructose
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28. Maltose
Maltose, two joined glucose subunits, gives barley
seeds a sweet taste
It is a disaccharide formed from two units
of glucose joined with an α(1→4) glycosidic bond.
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29. Lactose
A glucose molecule bonds to another
monosaccharide, galactose, the resulting
disaccharide is lactose (commonly called milk
sugar).
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30. Ploysaccharides
Polysaccharides are composed of many molecules
of simple sugars (usually glucose) linked together
in long chains called polymers
Their empirical formula is usually written
(C6H10O5)n, where n designates the number of
simple sugar subunits contained in the polymer
They are tasteless
Non reducing
On hydrolysis yield many monosacchardies
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31. Examples
Starch is the common form in which sugar is stored in
most plants and is an important food for animals
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34. Cellulose
ellulose is the main substance in the walls of plant
cells, helping plants to remain stiff and upright
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36. Chitin
Other biologically important polysaccharides include
chitin (a major component of the exoskeleton of
insects and of crustaceans, such as lobsters and
crabs)
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38. What are lipids?
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Lipids are a heterogeneous group of organic
compounds that are insoluble in water and soluble in
non-polar organic solvents like such as ether, alcohol,
and chloroform.
They naturally occur in most plants, animals,
microorganisms and are used as cell membrane
components, energy storage molecules, insulation,
and hormones.
40. Chemical Composition of Lipids
Lipid molecules are composed primarily of carbon,
hydrogen, and oxygen atoms, although some may
contain small amounts of phosphorus and nitrogen
They contain a much smaller proportion of oxygen
than do carbohydrates, as the formula for the fat,
tristearin, C57H110O6
The building blocks of fat molecules are fatty
acids and glycerol.
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41. What are fatty acids?
Fatty acids contain long hydrocarbon chains bonded to
carboxyl (±COOH) groups
Types of Fatty Acids:
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43. Unsaturated Fatty Acids
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Two common unsaturated fatty acids are Oleic acid and Linoleic acid
44. Polyunsaturated fatty acids
•
They have at least two double bonds in the carbon
chain
• Typically come from plants such as olives
• Tend to be liquid at room temperature
• It has so many bends that it starts to curve over onto
itself or twist around itself
Omega-3 and omega-6 fatty acids
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46. Types of Lipids
The three principal groups of lipids are;
Neutral fats
Phospholipids
Steroids
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49. 1. Neutral Lipids (Triglycerides)
Triglycerides are also known as triacylglycerols and
compose 95% of fat in the foods we eat.
Triglycerides are also the main fats we store in our
body
Three fatty acid molecules combine with one
glycerol molecule by joining to each of the three
carbon atoms in the glycerol backbone
Because there are three fatty acids, the resulting fat
molecule is called a triglyceride neutral fat, or
triacylglycerol.
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51. Beef fat, with three Stearic acids
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52. Although the glycerol portion of every fat molecule is the
same, there are many kinds of fatty acids and, therefore,
many kinds of fats.
Fatty acid molecules differ in the length of their carbon
chains and in the ways the carbon atoms combine.
The most common are even-numbered chains of 14 to 20
carbons
Unsaturated fats have low melting points because
their chains bend at the double bonds and the fat
molecules cannot align closely with one another,
which would lead to solidification.
Consequently, the fat may be fluid at room
temperature.
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53. A liquid fat is called an oil.
Most plant fats are unsaturated.
Animal fats, in contrast, are often saturated and
occur as hard or solid fats.
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54. 2. Phospholipid
A phospholipid molecule is similar to a fat molecule in that
it contains a glycerol portion and fatty acid chains.
However, the phospholipid has only two fatty acid chains
Phosphate (PO43) and nitrogen-containing groups replace
the third chain.
The polar phosphate and nitrogen groups are soluble in
water (hydrophilic) and form the “head” of the molecule;
the insoluble (nonpolar, hydrophobic) fatty acid portion
forms the “tail.”
The phospholipids are amphipathic .
The hydrophilic end usually contains a negatively charged
phosphate group, and the hydrophobic end usually consists
of two "tails" that are long fatty acid residues.
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55. The first phospholipid identified in 1847 as such in
biological tissues was lecithin (the most abundant
phopholipid in cell membrane),
or phosphatidylcholine, in the egg yolk of chickens by
the French chemist and pharmacist Theodore Nicolas
Gobley.
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56. Function of Phospholipids
Phospholipids are the major structural components of
cell membranes because of this tendency to be soluble
at one end and insoluble at the other.
They can form lipid bilayers because of
their amphipathic characteristic.
In eukaryotes, cell membranes also contain another
class of lipid, sterol, interspersed among the
phospholipids.
The combination provides fluidity in two dimensions
combined with mechanical strength against rupture
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57. 3. Steroids
Steroids are another class of lipid molecules, identifiable
by their structure of four fused rings.
Although they do not resemble the other lipids structurally,
steroids are included in lipid category because they are also
hydrophobic and insoluble in water.
Three of the rings are six-sided, and the fourth is five-sided.
The four rings contain a total of 17 carbons
Many steroids also have an –OH functional group attached
at a particular site, as shown for cholesterol below; such
steroids are also classified as alcohols, and are thus called
sterols.
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58. Example:
Cholesterol, the most common steroid, is mainly
synthesized in the liver and is the precursor to many
steroid hormones.
These include the sex hormones testosterone and
estradiol, which are secreted by the gonads (testes and
ovaries).
Cholesterol also serves as the starting material for other
important molecules in the body, including vitamin D and
bile acids, which aid in the digestion and absorption of
fats from dietary sources.
It’s also a key component of cell membranes, altering their
fluidity and dynamics.
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60. 4. Waxes
Waxes are another biologically important category of
lipids.
Wax covers the feathers of some aquatic birds and the leaf
surfaces of some plants, where its hydrophobic (water-
repelling) properties prevent water from sticking to, or
soaking into, the surface.
This is why water beads up on the leaves of many plants,
and why birds don’t get soaked through when it rains.
Structurally speaking, waxes typically contain long fatty
acid chains connected to alcohols by ester linkages,
although waxes produced by plants often have plain
hydrocarbons mixed in as well.
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61. PROTEINS: THE BASIS OF LIFE’S
DIVERSITY
What are proteins?
Proteins are large size and most abundant molecules
(macromolecules), polymers of structural units called
amino acids.
Proteins always contain atoms of carbon, hydrogen,
nitrogen, oxygen, and sometimes, sulfur
The individual building blocks of proteins are amino acids
AminoAcids
Amino acids always contain an amino group (±NH2), a
carboxyl group (±COOH), a hydrogen atom, and a
functional group, designated R, all bonded to a central
carbon atom:
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62. Continue…
The nature of the R group linked to the central carbon
atom determines the identity and unique chemical
properties of each amino acid.
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63. Five of the twenty naturally occurring amino
acids
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64. Peptide Bond
Covalent bonds called peptide bondslink individual
amino acids in chains.
In the formation of a peptide bond, the carboxyl group
of one amino acid bonds to the amino group of
another amino acid, with the elimination of water (a
dehydration synthesis reaction)
When two amino acids bond, they form a unit called a
dipeptide; three bonded amino acids form a
tripeptide. When many amino acids bond, they form
a chain called a polypeptide
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66. In different proteins, the chain of amino acids can vary
from fewer than 50 to more than 2,000 amino acids.
Each type of protein contains a specific number and
kind of amino acids arranged in a particular sequence.
The protein molecule may be coiled and folded, or it
may interact with other protein molecules to form a
unique three-dimensional structure.
Different kinds of protein molecules have different
shapes related to their particular functions in life
processes
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68. Structural Levels of Protein
A protein is not just a long string of amino acids; it is a
highly organized molecule.
For convenience, biochemists recognize four levels of
protein organization called primary, secondary, tertiary,
and quaternary structures.
1. Primary Structure:
The primary structure is the linear sequence of amino acids
in the polypeptide chains comprising the molecule
Amino acids are covalently linked by peptide bonds.
Each component amino acid in a polypeptide is called a
“residue” or “moiety”
Example: Insulin
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