Chemical components of living organisms

1. Chemical components of living organisms

2. Learning objectives • To identify the basic chemical components of living organisms. • To define roles of carbohydrates, proteins and lipids in terms of energy storage and structural components. • To describe formation of carbohydrate, proteins and lipid from basic units. • To identify deoxyribonucleic acid (DNA) and ribonucleic acid(RNA) with their bases. • To differentiate between DNA and RNA.

3. The basic chemical components of living organisms • Carbohydrate • Proteins • Lipids • Nucleic acids • Water • Mineral salts

4. Carbohydrate • Carbon + Hydrogen + Oxygen • General formula: Cx(H2O)y. • Types of carbohydrates: ~ Monosaccharides ~ Disaccharides ~ Polysaccharides

5. Monosaccharide • Sweet & soluble. • General formula: Cn(H2O)n. • Glucose, fructose & galactose

6. Glucose • Found in all living cells • Chief end-product of carbohydrate digestion in gut

7. Fructose • Found in fruits and in honey.

8. Galactose & ribose • Galactose ~ Found in milk • Ribose ~ Constituent of ribonucleic acid(RNA) and deoxyribonucleic acid (DNA)

9. Disaccharide • 2 monosaccharides joining together by glycosidic bond undergoing a condensation reaction. • Disaccharide can be split into its constituent monosaccharides by hydrolysis. • Sweet, soluble and crystalline • Maltose, sucrose, lactose

10. Maltose • Glucose + Glucose Maltose • Glucose + Glucose +……  starch • It is hydrolysed back to 2 glucose molecules by maltase.

11. Sucrose • Glucose + fructose  sucrose • It is also called cane-sugar. • It is hydrolysed back to glucose and fructose by invertase.

12. Lactose • Glucose + galactose lactose • It is hydrolysed back to glucose and galactose by lactase. • Lacking lactase in the body  lactose intolerance

13. Polysaccharides • Complex sugar • Compounds of a large number of monosaccharides units • Insoluble • Converted into monosaccharides upon hydrolysis • As food and energy store

14. Polysaccharide • Starch ~ major food reserve stored in plants but absent in animal. • Glycogen ~ animal starch, stored in liver & muscles. • Cellulose ~ constitute of plant cell wall, insoluble in water & dissolves in concentrated sulphuric acids.

15. Function of carbohydrates • As respiratory substrate • As storage material • As structure material

16. Tests for carbohydrates Reducing sugar: • Benedict’s test • Clinistix paper test Non-reducing sugar: • Acid hydrolysis • Enzyme action Starch • Iodine test

17. Lipids • Carbon + Hydrogen + Oxygen • Insoluble in water but dissolve in organic solvents. • Fat: semi-solid at room temperature • Oils: liquid at room temperature • Types of lipids: triglycerides, phospholipids

18. Food reserve Structural materials Insulation Water-proof layer Transport medium Metabolic regulators Energy source Protection Others Function of lipids

19. Tests for lipids • Grease spot test • Sudan III test

20. Proteins • Polymer of amino acids • Insoluble in water • Carbon + Hydrogen + Oxygen + nitrogen +/- sulphur & phosphorus • Basic units: amino acid

21. Proteins • Amino acid + Amino acid  Dipeptide • Dipeptide + Dipeptide  Polypeptide • The reaction “” is condensation. • 4 types of bonding: disulphide bond, ionic bond, hydrogen bond & hydrophobic interaction.

22. Structure of proteins • Primary structure • Secondary structure • Tertiary structure • Quaternary structure

23. Denaturation • Denaturation ~ loss of specific three dimensional conformation of a protein molecule; ~ but the amino acids sequence remains unaffected; ~ loss of biological activities

24. Factors causing denaturation • Heat or radiation • Extreme pH • Inorganic chemicals • Organic chemicals • Mechanical force • Strong hydrogen bond former

25. Renaturation • the protein resume its natural configuration; • the protein regains its normal activity

26. Fibrous protein ~ regular repetitive sequences of amino acid; ~ parallel chain; ~ insoluble in water ~ e.g. collagen of tendons & ligaments Globular protein ~ irregular sequences of amino acid; ~ spherical & globular shapes chains; ~ e.g. enzymes, antibodies & hormones. Types of proteins

27. Structural materials Biocatalyst Metabolic regulators Transportation Protection Muscle contraction Storage Toxins Respiratory substrate Functions of proteins

28. Tests for proteins • Biuret test • Albustix paper test

29. Nuleotides • Phosphoric acid + Pentose sugar + Organic base • The three components are combined by condensation reaction

30. Types of nucleotides • Mononucleotides: only one nucleotide unit, e.g. ATP • Dinucleotides: 2 nucleotides e.g. NAD • Polynucleotides: repeated condensation of nucleotides e.g. RNA & DNA

31. RNA • Ribonucleic acid • Single –stranded polymer of nucleotide • Organic bases: A, G, C AND U

32. DNA • Deoxyribonucleic acid • Double-strand polymer, form double helix • Organ bases: A, G, C and T

33. DNA Single strand Base: A, T, C & G Sugar: Deoxyribose Size: long & large Stability: alkali-stable Function: carry genetic information Occurrence: innucleus RNA Single strand Base: A, U, C & G Sugar: ribose Size: short & small Stability: stable Function: protein synthesis, carry genetic information from DNA Occurrence: throughout cell DNA vs RNA

34. Water • Comprise 65-95% of living cells. • High specific heat. • Strong hydrogen bond. • Universal solvent. • High tensile strength and high viscosity. • High surface tension

35. Importance of water to life • Component of protoplasm. • Universal solvent. • Participating in metabolic process. • Cell turgidity. • Surface film. • Temperature stability. • Translocation medium.

36. Mineral salt • Calcium • Chlorine • Phosphate • Fluorine • Iodine • Iron