Biological molecules

• Secondary structure involves hydrogen bonds between peptide groups forming alpha helices or beta pleated sheets.
• Primary structure refers to the sequence of amino acids in a protein chain.
• The three-dimensional structure of proteins is determined by the primary, secondary, tertiary, and quaternary structures.
• Tertiary structure is the overall shape of the protein, determined by interactions such as disulfide bridges, ionic bonds, van der Waals forces, and hydrophobic interactions.
• Tertiary structure is formed by interactions within one polypeptide, such as disulfide bridges, ionic bonds, van der Waals forces, and hydrophobic interactions.
• Quaternary structure refers to multiple polypeptides coming together to form one functional unit.
• Quaternary structure refers to multiple polypeptides coming together to form one functional unit.
• Denaturation can occur due to changes in pH, temperature, or chemical agents that disrupt noncovalent interactions.
• Denaturation can occur due to changes in pH, temperature, or chemical agents that disrupt noncovalent interactions.
• Quaternary structure describes how multiple polypeptides interact with each other to form a functional protein complex.
• Protein folding occurs through interactions such as disulfide bridges, ionic bonds, van der Waals forces, and hydrophobic interactions.
• Benedict’s solution can be used to test for reducing sugars, including glucose, fructose, and maltose
• Benedict’s solution does not test for sucrose
• Acid hydrolysis can break glycosidic bonds in non-reducing sugars
• Semi-quantitative methods for Benedict’s test:

  • Measure time for color change
  • Use colorimetry to estimate concentration (higher glucose concentration means lower absorbance)
• Iodine/potassium iodide test turns blue/black if starch is present
• Emulsion test with ethanol and water shows a milky color for lipids
• Biuret test changes color from blue to purple in the presence of proteins
• Carbohydrates consist of monosaccharides, disaccharides, and polysaccharides
• Monosaccharides like glucose are important substrates for respiration
• Disaccharides include maltose, sucrose, and lactose
• Polysaccharides like glycogen, starch, and cellulose are formed by glycosidic bonds
• Glycogen is the main energy storage molecule in animals, formed by alpha glucose with many side branches
• Starch consists of amylose and amylopectin, with different structures affecting digestion speed
• Cellulose provides structural support in plant cells, composed of beta glucose chains
• Saturated lipids in animal fats lack carbon-carbon double bonds, while unsaturated lipids in plants contain double bonds
• Triglycerides are composed of glycerol and three fatty acids, used as energy reserves
• Phospholipids have hydrophilic heads and hydrophobic tails, forming micelles in water
• Proteins are made of amino acids linked by peptide bonds, with primary, secondary, tertiary, and quaternary structures
• Primary structure is the order and number of amino acids, secondary structure includes alpha helix and beta pleated sheet formations
• Tertiary structure is the 3D shape of the protein, globular proteins are compact and soluble, while fibrous proteins are long and insoluble
• Quaternary structure consists of multiple subunits closely packed together, like in haemoglobin
• Water is a polar molecule, a metabolite, solvent, and has high specific heat capacity and latent heat of vaporization
• Water exhibits strong cohesion, supporting capillary action and high surface tension