IN FOCUS

GSA Lecture 1
Dr. Bushra Javed Siddiqui
BIOLOGICAL SCIENCES
Biomolecules
Balance diet
Objectives:
◦ Define Biomolecules (Carbohydrates, Proteins, Lipids, Nucleic acid, Vitamins and minerals) and
Enzymes
◦ Sources and properties
◦ Types (Classification)
◦ Functions (Importance)
◦ Balanced diet (Components) and caloric requirement
◦ Importance of balanced diet
Biomolecules:
◦ Definition: Naturally occurring molecules in living organisms i.e. organic and inorganic.
◦ Macro-molecules: Required in large amounts for proper functioning of body.
◦ Example: Carbohydrates, Proteins, Lipids, and Nucleic Acid.
◦ Micro-molecules: Required in lesser amounts.
◦ Example: Vitamins and Minerals.
Carbohydrates:
◦ Definition: “Organic compunds having Carbon, Oxygen, and Hydrogen in specified amounts”.
◦ Also known as saccharides.
◦ Sources: Cereals, fruits and vegetables (dates, sugar beet, potato, sugarcane).
◦ Properties: 3.9 cal/gram.
◦ Glucose is produced as an end product of carbohydrate breakdown, and is considered the fundamental
unit of carbohydrates.
◦ Empirical Formula: Cm(H2O)n (Hydrogen and Oxygen ratio is 2:1, usually)
Carbohydrates: (cont.)
◦ Types (Classification):

1. Monosaccharides:
• Simple sugars because cannot be further hydrolysed.
• Sweet and Water soluble.
• General Formula is Cn(H20)n.
• Subdivide on the basis of number of Carbon atoms; triose, tetrose, pentoses, hexoses, heptoses, etc.
• Examples: Glucose (blood sugar), Galactose (milk sugar), and fructose (fruit sugar)6
• 6CO2 + 12H2O C6H12O6 + 6O2 + 6H2O (Equation for glucose synthesis)
Carbohydrates: (cont.)
2. Oligosaccharides
◦ Yield 2-10 molecules of monosaccharides (similar or different) on hydrolysis.
◦ Less sweet and less water soluble.
◦ Two monosaccharides are linked through glycosidic bond (Covalent bond).
◦ General formula in Cn(H2O)n-1, n-2, n-3,… for di, tri, tetra-saccharides and so on.
◦ Example: Sucrose (Glucose + Fructose), Lactose (Glucose + Galactose), and Maltose (Glucose +
Glucose)
Carbohydrates: (cont.)
3. Polysaccharides:
◦ Yield more than 10 molecules of monosaccharides on hydrolysis.
◦ Tasteless and Branched structure which makes them sparingly soluble.
◦ General formula is (C6H10O5)n.
◦ Types: Homo-polysaccharides (yield same monomers on hydrolysis such as Starch, Gylcogen, Cellulose,
Pectin), and hetero-polysaccharides (yield different monosaccharides on hydrolysis such as Hyaluronic
Acid and Chondroitin).
Carbohydrates: (cont.)
◦ Functions (Importance):
◦ Chief and instant energy source i.e. 1 molecule of glucose = 38 ATP moleclues.
◦ Regulation of Nervous tissue.
◦ Structural and protective components such as surface antigens, receptor molecules, antibiotics, cell wall
in plants and micro-organisms, and connective tissues in animals.
◦ Maintenance of biological transport, cell-cell communication, and activation of growth factors.
◦ Fibre content for prevention of constipation.
Proteins:
◦ Definition: “Chief building blocks of the body, made up of amino-acid monomers, containing; carbon,
hydrogen, oxygen, and nitrogen”.
◦ They may also contain sulphur and phosphorus.
◦ Sources: Animal (meat, fish, egg, poultry),
◦ and plants (pulses and beans)
◦ Properties: 4.1 cal/gm.
◦ Composition:
1. Essential Amino Acids (9);
◦ Not synthesized by the body and must be obtained from external dietary sources.
◦ Mneumonic (PVT TIM HALL) – Phenylalanine, valine, Threonine, Tryptophan, Isoleucine,
Methionine, Histidine, Arginine, Leucine, and Lysine.
◦ Arginine is essential for infants and children only.
Proteins: (cont.)
2. Non-Essential Amino Acids (10):
◦ Are synthesized by the body itself in sufficient quantities.
◦ Alanine, Asparagine, Aspartic Acid, Cysteine, Glutamic Acid, Glutamine, Glycine, Proline, Serine,
and Tyrosine.
3. Semi-essential Amino Acids (2):
◦ Are synthesized by the body but not in sufficient quantity.
◦ Also known as conditionally essential Amino Acids.
◦ Histidine and Arginine.
Proteins: (cont.)
◦ Classification on the Basis of structure:
1. Primary Structure:
◦ Long Chain of AA.
◦ Particular Sequence.
◦ Non-functional.
◦ Example: Alpha and beta chains of haemoglobin molecule.
2. Secondary Structure:
◦ AA polypeptide chain coiled into spiral or helix.
◦ 3D structure i.e. Alpha-helix and beta-pleated.
◦ Hydrogen bonds.
◦ Example: Keratin and silk fibres.
Proteins: (cont.)
3. Tertiary Structure:
◦ AA polypeptide chains stabilized by folding and coiling.
◦ Ionic or hydrophobic bonds, or Disulphide Bridges.
◦ Example: Globulins of blood (carrier proteins such thyroglobulin, immunoglobulins, and myoglobin).
4. Quaternary Structure:
◦ A mixture of the aforementioned structures assembled together to form a protein molecule.
◦ Example: Hemoglobulin and Insulin.
Structure of
proteins
Proteins: (cont.)
◦ Classification on the Basis of Function:
1. Enzymatic Proteins: Catalytic Activity, e.g. Pepsin, and Trypsin.
2. Structural Proteins: Support and Protection, e.g. Collagen, Elastin, and Keratin.
3. Transport or Carrier Proteins: Transport of ions and molecules, e.g. Myoglobin, and haemoglobin.
4. Nutrient and storage Proteins: Nourishment for growth and maintenance of body functions.
5. Contractile Proteins: Muscle contraction and movement, e.g. Actin and Myosin.
6. Hormones: Maintenance of body functions and homeostasis e.g. Insulin and adrenaline.
Proteins: (cont.)
◦ Functions of Proteins:
◦ Growth, maintenance, and repair of body structure.
◦ Regulation of body functions through enzymes and hormones.
◦ Protection through antibodies (Immuno-globlulins).
◦ Movement both voluntary and involuntary through actin and myosin.
◦ Skin appendages such as hair, nails, feathers, horns, and beaks.
◦ Carrier proteins such as haemoglobin and myoglobin.
THANK YOU
Any questions?