(a) What are monosaccharides? Give example.
Monosaccharides are the simplest form of carbohydrates that cannot be hydrolyzed into smaller carbohydrate units
. They are the building blocks of more complex sugars. Examples include Glucose and Fructose.(b) What are glycoconjugates? Name two glycoconjugates.
Glycoconjugates are biologically active molecules consisting of carbohydrates covalently linked to other chemical species such as proteins or lipids
. Two examples are Glycoproteins and Glycolipids.(c) Write a brief note on structural polysaccharides.
Structural polysaccharides provide mechanical support and protection to cells and organisms
. Cellulose is the primary structural component of plant cell walls, while Chitin provides structural integrity to the exoskeletons of arthropods and fungal cell walls.(a) What are carbohydrates? Explain the structure of any monosaccharide with proper illustration. Add a note on the optical activity of monosaccharide. Mention the biological importance of monosaccharides in nature. [2+4+2+2=10]
Carbohydrates: These are polyhydroxy aldehydes or ketones, or substances that yield such compounds on hydrolysis
. They serve as a primary energy source and structural components.Structure of Glucose (Monosaccharide): Glucose (C6H12O6) is an aldohexose
. It exists in open-chain and cyclic (Haworth) forms. In the cyclic form, it typically forms a six-membered pyranose ring.Optical Activity: Monosaccharides possess asymmetric carbon atoms, making them optically active
. They can rotate the plane of polarized light to the right (dextrorotatory) or left (levorotatory).Biological Importance: Monosaccharides like glucose are the universal fuel for cells
. Ribose and deoxyribose are essential components of RNA and DNA, respectively.(b) Write short notes on any two: (i) Polysaccharides and biological importance (ii) Glycosylation and significance (iii) Structure of oligosaccharides.
[5x2=10](i) Polysaccharides: Long chains of monosaccharide units
. Starch and Glycogen serve as energy storage in plants and animals, respectively.(ii) Glycosylation: The enzymatic process that attaches glycans to proteins or lipids
. It is significant for protein folding, stability, and cell-cell recognition.(iii) Oligosaccharides: Carbohydrates containing 3 to 10 monosaccharide units
. They often function as markers on cell surfaces.(a) What are lipids? Name the most common type of lipid present in the brain.
Lipids are organic compounds that are insoluble in water but soluble in organic solvents
. The most common lipid in the brain is Cholesterol (or specialized phospholipids/sphingolipids).(b) What are Phospholipids? Give example.
Phospholipids are compound lipids containing a phosphate group, a glycerol/sphingosine backbone, and fatty acids
. Example: Lecithin (Phosphatidylcholine).(c) Role of steroids in our body.
Steroids act as important hormones (e.g., testosterone, estrogen), components of cell membranes (cholesterol), and aid in fat digestion as bile acids
.(a) What are saturated fatty acids? Discuss structure with illustration. Differentiate between saturated and unsaturated fatty acids. Mention physiological importance. [1+4+2+3=10]
Saturated Fatty Acids: Fatty acids with no double bonds between carbon atoms
.| Feature | Saturated Fatty Acids | Unsaturated Fatty Acids |
|---|---|---|
| Double Bonds | None | One or more |
| State at Room Temp | Solid (usually) | Liquid (usually) |
Physiological Importance: They serve as concentrated energy stores and structural components of cell membranes
. Essential fatty acids (unsaturated) are precursors to prostaglandins.(b) Short notes on any two: (i) Outline classification of lipid (ii) Glycolipids (iii) Triacylglycerols and functions.
[5x2=10]Triacylglycerols: Esters of glycerol with three fatty acids
. Their primary function is long-term energy storage in adipose tissue.(a) Essential and non-essential amino acids.
Essential: Cannot be synthesized by the body and must be taken in diet (e.g., Valine)
. Non-essential: Can be synthesized by the body (e.g., Alanine).(b) Secondary structures found in protein.
The main types are Alpha-helix and Beta-pleated sheets
.(c) Derived proteins.
Proteins formed by the action of heat, acids, or enzymes on natural proteins (e.g., peptones, proteoses)
.(a) What are amino acids? Classification based on polarity. General properties. Physiological importance. [1+4+3+2=10]
Amino Acids: Organic compounds containing both amino (–NH2) and carboxyl (–COOH) groups
.Polarity Classification: Non-polar (hydrophobic), Polar uncharged, Polar acidic (negatively charged), and Polar basic (positively charged)
.Properties: Amphoteric nature, Zwitterion formation, and high melting points
.(b) Proteins, classification, and stabilizing bonds.
[1+5+4=10]Proteins are classified into Simple, Conjugated, and Derived
. Bonds include Peptide bonds (Primary), Hydrogen bonds (Secondary), Disulfide bridges, and Hydrophobic interactions (Tertiary/Quaternary).(a) Active site of an enzyme.
The specific region of an enzyme where substrate molecules bind and undergo a chemical reaction
. It determines enzyme specificity.(b) What are Km and Vmax?
Vmax: Maximum rate of reaction
. Km: Substrate concentration at which reaction rate is half of Vmax.(c) Classify vitamins with example.
Fat-soluble: A, D, E, K
. Water-soluble: B-complex, C.(a) Enzymes, IUB classification, and general properties.
[2+5+3=10]IUB Classification: 1. Oxidoreductases, 2. Transferases, 3. Hydrolases, 4. Lyases, 5. Isomerases, 6. Ligases
.(b) Short notes on enzyme mechanism theories, factors affecting rate, and water-soluble vitamins.
[5x2=10](a) Purines and pyrimidines.
Purines: Double-ringed bases (Adenine, Guanine)
. Pyrimidines: Single-ringed bases (Cytosine, Thymine, Uracil).(b) Differences between DNA and RNA.
DNA has deoxyribose and thymine; RNA has ribose and uracil. DNA is double-stranded; RNA is usually single-stranded.
(c) Hoogsteen base pair.
An alternative form of base pairing where the purine uses the N7 position instead of the N1 position used in Watson-Crick pairing
.(a) Nucleosides and nucleotides. Watson and Crick model of DNA. Types of DNA. [2+5+3=10]
Nucleoside: Base + Sugar
. Nucleotide: Base + Sugar + Phosphate.Watson-Crick Model: DNA is a double helix with antiparallel strands, sugar-phosphate backbone, and complementary base pairing (A=T, G≡C)
.(b) Short notes on RNA types, Denaturation/Renaturation, and DNA chromaticity.
[5x2=10]