Biomolecules Notes 2024-25 PDF

# Biomolecules ## Carbohydrates - **Definition:** Organic compounds that include polyhydroxy aldehydes and polyhydroxy ketones. - **Classification:** - **Monosaccharides:** Cannot be broken into simpler units on hydrolysis. (e.g. glucose and fructose). - **Oligosaccharides:** Contain 2-10...

# Biomolecules ## Carbohydrates - **Definition:** Organic compounds that include polyhydroxy aldehydes and polyhydroxy ketones. - **Classification:** - **Monosaccharides:** Cannot be broken into simpler units on hydrolysis. (e.g. glucose and fructose). - **Oligosaccharides:** Contain 2-10 monosaccharide units. (e.g. disaccharides, trisaccharides, etc.). - **Disaccharides:** Produce two monosaccharides on hydrolysis. (e.g. sucrose, lactose, and maltose). - **Polysaccharides:** Produce a large number of monosaccharides on hydrolysis. (e.g. starch, cellulose, and glycogen). - **Importance of carbohydrates:** - Major source of energy - Structural components of cell walls (cellulose) - Storage molecules (starch, glycogen) - Components of nucleic acids (ribose, deoxyribose) **Examples of carbohydrates:** | Carbohydrate | Classification | Reducing Sugar | |---|---|---| | Glucose | Monosaccharide | Yes | | Fructose | Monosaccharide | Yes | | Sucrose | Disaccharide | No | | Lactose | Disaccharide | Yes | | Maltose | Disaccharide | Yes | | Starch | Polysaccharide | Yes | | Cellulose | Polysaccharide | No | | Glycogen | Polysaccharide | Yes | **Reducing vs. Non-Reducing sugars** - **Reducing sugars:** Reduce Fehling's solution and Tollen's reagent. (e.g. glucose and fructose) - **Non-reducing sugars:** Do not reduce Fehling's solution and Tollen's reagent. (e.g. sucrose) ## Proteins - **Structural units:** Amino acids - **Basic structure:** - **Primary:** Sequence of amino acids in a polypeptide chain. - **Secondary:** Folding of the polypeptide chain into a-helix or ẞ-pleated sheet structures. - **Tertiary:** Overall three-dimensional shape of a single polypeptide chain. - **Quaternary:** Arrangement of multiple polypeptide chains in a protein. - **Functions:** - Enzymes: Catalyze biochemical reactions. - Hormones: Regulate biological activity. - Structural components: Provide support and shape to cells and tissues. **Types of amino acids based on their acidic/basic properties:** - **Acidic amino acids:** Contain two carboxylic groups and one amino group. (e.g. glutamic acid) - **Basic amino acids:** Contain two or more amino groups and one carboxylic group. (e.g. lysine) - **Neutral amino acids:** Contain one amino group and one carboxylic group. (e.g. glycine) **Zwitter ion formation:** - Amino acids in aqueous solution exist as zwitter ions, with a positive charge on the amino group and a negative charge on the carboxyl group. - This dipolar nature makes amino acids amphoteric and able to react with both acids and bases. **Isoelectric point:** - The pH at which an amino acid exists as a zwitter ion and does not migrate in an electric field. **Protein structure:** | Protein Type | Structure | Solubility | Stability | |---|---|---|---| | Fibrous proteins | Thread-like, extended | Insoluble in water | Generally more stable | | Globular proteins | Folded, spherical | Soluble in water | Generally less stable | ## Nucleic Acids - **Structure:** Polymers of nucleotides, consisting of a pentose sugar, a phosphate group, and a nitrogenous base. - **Functions:** - Store and transmit genetic information. - Direct protein synthesis. **Types of nucleic acids:** - **Deoxyribonucleic acid (DNA):** - Double-stranded helix. - Sugar: Deoxyribose. - Bases: Adenine, Guanine, Cytosine, Thymine. - Function: Stores genetic information and directs protein synthesis. - **Ribonucleic acid (RNA):** - Single-stranded. - Sugar: Ribose. - Bases: Adenine, Guanine, Cytosine, Uracil. - Function: Involved in protein synthesis. ## Vitamins - **Definition:** Organic compounds required in small amounts for normal growth and function. - **Classification:** - **Fat-soluble:** Vitamins A, D, E, and K. - Stored in the body, but toxicity can occur with excessive intake. - **Water-soluble:** Vitamins B and C. - Not stored in the body and are excreted in excess. **Deficiency diseases:** | Vitamin | Deficiency disease | |---|---| | Vitamin A | Night blindness, xerophthalmia | | Vitamin B | Beriberi, pellagra, anemia | | Vitamin C | Scurvy | | Vitamin D | Rickets | | Vitamin E | Sterility | | Vitamin K | Hemorrhage | ## Key Concepts and Questions to Consider: **Carbohydrates:** - How do monosaccharides differ from disaccharides and polysaccharides? - What is the role of glycosidic linkage in the formation of carbohydrates? - What are the differences between starch, cellulose, and glycogen? - Explain the structure and function of reducing and non-reducing sugars. **Proteins:** - What are the four levels of protein structure? - What is the function of the peptide bond? - What factors can cause denaturation of a protein and how does this impact its function? - Explain the concept of zwitter ions and the isoelectric point of amino acids. **Nucleic Acids:** - What are the differences between DNA and RNA? - Explain the structure of a nucleotide. - How are nucleotides linked together to form a nucleic acid chain? - What is the significance of the double helix structure of DNA?