Carbohydrates, Proteins, Polymers | Jamb Chemistry

Carbohydrates: General Introduction

1. Carbohydrates are organic compounds composed of carbon (C), hydrogen (H), and oxygen (O).
2. Their general formula is ${C}_n({H}_2{O})_m$, where $n$ and $m$ are integers.
3. Carbohydrates are classified into monosaccharides, disaccharides, and polysaccharides.
4. They are a major source of energy for living organisms.
5. Examples include glucose, sucrose, starch, and cellulose.
6. Monosaccharides are the simplest form of carbohydrates.
7. Disaccharides consist of two monosaccharide units.
8. Polysaccharides are long chains of monosaccharide units.
9. Carbohydrates are found in foods like grains, fruits, and vegetables.
10. They provide energy during respiration and act as structural materials.
    paragraph

Monosaccharides (Simple Sugars)

11. Monosaccharides have the general formula ${C}_n{H}_{2n}t{O}_n$.
12. Examples of monosaccharides include glucose, fructose, and galactose.
13. Glucose (${C}_6{H}_{12}{O}_6$) is the primary energy source for cells.
14. Fructose (${C}_6{H}_{12}{O}_6$) is found in fruits and honey.
15. Galactose (${C}_6{H}_{12}t{O}_6$) combines with glucose to form lactose.
16. Monosaccharides are reducing sugars because they can donate electrons.
17. They react with Fehling's solution and Benedict's solution to produce a brick-red precipitate.
18. Monosaccharides form cyclic structures, known as pyranose (6-membered) or furanose (5-membered) rings.
19. Glucose can exist in alpha ($\alpha$-glucose) and beta ($\beta$-glucose) forms.
20. Ribose (${C}_5{H}_{10}{O}_5$) is a pentose sugar found in RNA.
    paragraph

Disaccharides

21. Disaccharides are formed by the condensation of two monosaccharides.
22. A glycosidic bond connects the two sugar units.
23. Disaccharides have the formula ${C}_{12}{H}_{22}{O}_{11}$.
24. Examples include maltose, sucrose, and lactose.
25. Maltose = glucose + glucose.
26. Sucrose = glucose + fructose (common table sugar).
27. Lactose = glucose + galactose (milk sugar).
28. Sucrose is non-reducing because it lacks a free aldehyde group.
29. Maltose and lactose are reducing sugars because they have free -CHO groups.
30. Disaccharides can be hydrolyzed into their monosaccharide units by acids or enzymes.
    paragraph

Polysaccharides

31. Polysaccharides are complex carbohydrates made of long chains of monosaccharides.
32. They have the general formula $({C}_6{H}_{10}{O}_5)_n$.
33. Examples include starch, glycogen, and cellulose.
34. Starch is the storage polysaccharide in plants.
35. Glycogen is the storage polysaccharide in animals.
36. Cellulose is a structural polysaccharide found in plant cell walls.
37. Starch consists of amylose (linear) and amylopectin (branched).
38. Cellulose has beta-1,4-glycosidic bonds that form rigid fibers.
39. Polysaccharides are insoluble in water and are not sweet-tasting.
40. Hydrolysis of polysaccharides produces simpler sugars.
    paragraph

Chemical Tests for Simple Sugars

41. Benedict’s Test: Reducing sugars react to form a red precipitate.
42. Fehling’s Test: Reducing sugars reduce Fehling’s solution to a red-brown cuprous oxide.
43. Molisch’s Test: Carbohydrates react with concentrated ${H}_2{SO}_4$ to form a violet ring.
44. Non-reducing sugars must first be hydrolyzed to give a positive test.
45. Concentrated ${H}_2{SO}_4$ dehydrates simple sugars into black carbon.
46. This reaction is known as charring.
47. The Iodine Test detects starch, producing a blue-black color.
48. Polysaccharides do not give positive Benedict’s or Fehling’s tests unless hydrolyzed.
49. Hydrolysis of sucrose gives glucose and fructose.
50. Tests help distinguish reducing and non-reducing sugars.
    paragraph

Hydrolysis of Complex Sugars

51. Hydrolysis breaks down complex carbohydrates into simpler sugars.
52. Starch ($({C}_6{H}_{10}{O}_5)_n$) is hydrolyzed into glucose (${C}_6{H}_{12}{O}_6$).
53. Cellulose can be hydrolyzed by concentrated acids into glucose.
54. Enzymes like amylase hydrolyze starch into maltose and glucose.
55. Hydrolysis of polysaccharides is important in food digestion.
56. Cotton fibers consist of cellulose, which is hydrolyzed for industrial purposes.
57. Starch from cassava is hydrolyzed in the production of ethanol.
58. Hydrolysis produces fermentable sugars used in alcohol production.
59. Acid hydrolysis of cellulose is slower due to its strong beta-linkages.
60. Hydrolyzed starch is used in biofuel production.
    paragraph

Uses of Sugars and Starch

61. Glucose is used in fermentation to produce alcoholic beverages.
62. Starch from cassava and grains provides raw material for ethanol production.
63. Ethanol (${C}_2{H}_5{OH}$) is used as an industrial solvent.
64. Glucose is used in the medical field as an intravenous fluid.
65. Starch is used in the textile industry for fabric sizing.
66. Sugars are used in pharmaceuticals as sweeteners and coating agents.
67. Fermentation of sugar produces beer, wine, and spirits.
68. Molasses, a sugar by-product, is a key raw material for ethanol.
69. Starch derivatives are used as adhesives in paper production.
70. Sugar serves as a preservative in jams and jellies.
    paragraph

Proteins: Primary Structure and Hydrolysis

71. Proteins are made up of amino acids joined by peptide bonds.
72. The primary structure is the specific sequence of amino acids.
73. Proteins undergo hydrolysis to release amino acids.
74. Hydrolysis can occur using acids, bases, or proteolytic enzymes.
75. Ninhydrin Test detects amino acids, producing a purple color.
76. Biuret Test detects peptide bonds and turns violet in proteins.
77. Millon’s Test gives a red color with proteins containing tyrosine.
78. Xanthoproteic Test detects aromatic amino acids, producing a yellow color.
79. Proteins are essential for growth, repair, and enzymes.
80. Hydrolysis of proteins provides amino acids for industrial and nutritional purposes.
    paragraph

Enzymes and Their Functions

81. Enzymes are biological catalysts made of proteins.
82. They speed up chemical reactions without being consumed.
83. Enzymes are specific to their substrates (lock-and-key model).
84. Examples include amylase, protease, and lipase.
85. Enzymes lower the activation energy of reactions.
86. Amylase converts starch into maltose.
87. Protease breaks down proteins into amino acids.
88. Enzymes are used in food, textile, and pharmaceutical industries.
89. Enzymes work best at optimum pH and temperature.
90. Denaturation occurs when enzymes lose their structure.
    paragraph

Rubber and Polymers

91. Natural rubber is made of isoprene $( {C}_5{H}_8$) units.
92. Synthetic rubber is produced from petrochemical monomers.
93. Vulcanization of rubber involves adding sulfur for strength.
94. Examples of synthetic rubber include neoprene and Buna-S.
95. Polymers are macromolecules made of repeating monomer units.
96. Addition polymerization joins unsaturated monomers (e.g., polyethylene).
97. Condensation polymerization eliminates small molecules like water (e.g., nylon).
98. Thermoplastics can be reshaped by heating (e.g., PVC).
99. Thermosetting plastics are rigid and cannot be reshaped (e.g., Bakelite).
100. Polymers are used in textiles, construction, and packaging.
     paragraph

Summary of Key Points

101. Carbohydrates provide energy and structural support.
102. Monosaccharides are simple sugars like glucose (${C}_6{H}_{12}{O}_6$).
103. Disaccharides include sucrose, maltose, and lactose.
104. Polysaccharides like starch and cellulose have structural and storage roles.
105. Chemical tests detect reducing sugars, starch, and proteins.
106. Proteins are hydrolyzed into amino acids and tested with Biuret and Ninhydrin.
107. Enzymes catalyze biological reactions and are highly specific.
108. Natural and synthetic rubbers are essential industrial materials.
109. Polymers are classified into addition and condensation types.
110. Thermoplastics and thermosetting plastics have unique properties.
111. Hydrolysis breaks complex carbohydrates into simpler units.
112. Sugars are fermented into ethanol for industrial and beverage use.
113. Cellulose is used in textiles, while starch is key in food and fuel production.
114. Rubber is vital for tyres, gloves, and industrial belts.
115. Proteins are fundamental for biological functions.
116. Amino acid tests confirm the presence of proteins.
117. Enzymes are irreplaceable in digestion, industry, and medicine.
118. Carbohydrates, proteins, and polymers form the backbone of life and industry.
119. Rubber and plastics revolutionized manufacturing and transportation.
120. These concepts are vital to understanding the chemistry of living and non-living systems.

I recommend you check my Post on the following: