BIOMOLECULES- CARBOHYDRATES, PROTEINS, VITAMINS AND FATS

Carbohydrates

• They are organic compounds composed of carbon, hydrogen, and oxygen atoms. They are one of the three macronutrients essential for human nutrition, alongside proteins and fats. Carbohydrates serve as a primary source of energy for the body and play important roles in various physiological functions. 
• The basic building blocks of carbohydrates are monosaccharides, which are single sugar molecules. Examples include glucose, fructose, and galactose.
• Monosaccharides can join together through chemical bonds called glycosidic bonds to form larger carbohydrate molecules, such as disaccharides (e.g., sucrose, lactose) and polysaccharides (e.g., starch, glycogen, cellulose).

Proteins 

• Proteins are macromolecules made up of amino acid chains and play essential roles in the structure, function, and regulation of the body's tissues and organs. They are one of the three macronutrients necessary for human nutrition, along with carbohydrates and fats.
• Proteins are composed of long chains of smaller molecules called amino acids.
• There are 20 different amino acids commonly found in proteins, each with a unique side chain (R group) attached to a central carbon atom.
• Amino acids can be classified into essential amino acids, which must be obtained from the diet, and non-essential amino acids, which the body can synthesize from other molecules.

• Vitamins 
  • Vitamins are organic compounds required by the human body in small quantities to maintain normal physiological functions.
  • They are essential for various metabolic processes, growth, and overall health.
• Classification:
  • Vitamins are classified into two main groups based on their solubility:
    • Fat-Soluble Vitamins: Vitamins A, D, E, and K.
    • Water-Soluble Vitamins: B-complex vitamins (B1, B2, B3, B5, B6, B7, B9, B12) and vitamin C.
• Functions:
  • Antioxidant Activity: Vitamins A, C, and E act as antioxidants, protecting cells from oxidative damage caused by free radicals.
  • Energy Metabolism: B-complex vitamins are involved in energy metabolism, converting carbohydrates, proteins, and fats into energy.
  • Bone Health: Vitamin D is crucial for calcium absorption and bone mineralization, promoting bone health and preventing conditions like osteoporosis.
  • Blood Clotting: Vitamin K is necessary for the synthesis of proteins involved in blood clotting, preventing excessive bleeding.
  • Immune Function: Vitamins C, D, and E support immune function and help the body defend against infections and diseases.
• Deficiency and Toxicity:
  • Deficiencies in vitamins can lead to various health problems and diseases. For instance, vitamin D deficiency can result in rickets in children and osteomalacia in adults.
  • Excessive intake of certain vitamins, especially fat-soluble vitamins, can lead to toxicity and adverse health effects. For example, excessive vitamin A intake can cause liver damage and birth defects.

Cholesterol 

• Cholesterol is a waxy, fat-like substance found in the cells of the body. It is a type of lipid and is essential for various physiological functions.
• Cholesterol is a sterol molecule composed of four interconnected carbon rings, along with a hydrocarbon tail and a hydroxyl (-OH) group.
• It is insoluble in water but soluble in fats and organic solvents.

Sources of Cholesterol:

• Cholesterol is produced primarily by the liver, but it is also obtained from dietary sources.
• Dietary sources of cholesterol include animal-based foods such as meat, poultry, fish, eggs, and dairy products.
• Plant-based foods generally do not contain cholesterol unless they are processed with added fats or animal-derived ingredients.

Functions of Cholesterol:

• Cell Membrane Structure: Cholesterol is a key component of cell membranes, where it helps maintain membrane fluidity and stability.
• Hormone Synthesis: Cholesterol is a precursor for the synthesis of steroid hormones, including cortisol, aldosterone, estrogen, progesterone, and testosterone.
• Bile Acid Production: Cholesterol is converted into bile acids in the liver, which aid in the digestion and absorption of dietary fats in the intestines.
• Vitamin D Synthesis: Cholesterol is a precursor for the synthesis of vitamin D in the skin in response to sunlight exposure.

Transport of Cholesterol:

• Cholesterol is transported in the bloodstream within lipoprotein particles, which are complex structures composed of cholesterol, triglycerides, phospholipids, and proteins.
• There are several types of lipoproteins, including low-density lipoprotein (LDL), high-density lipoprotein (HDL), and very-low-density lipoprotein (VLDL), each with different roles in cholesterol metabolism.
• LDL cholesterol is often referred to as "bad" cholesterol because high levels of LDL are associated with an increased risk of cardiovascular diseases, while HDL cholesterol is considered "good" cholesterol because it helps remove excess cholesterol from the bloodstream and transport it to the liver for excretion.

Health Implications:

• Elevated levels of LDL cholesterol in the blood can lead to the buildup of cholesterol plaques in the walls of arteries, a condition known as atherosclerosis. Atherosclerosis is a major risk factor for coronary artery disease, heart attack, and stroke.
• Conversely, higher levels of HDL cholesterol are associated with a reduced risk of cardiovascular disease, as HDL helps remove excess cholesterol from the bloodstream.

Fats

• Fats, also known as lipids, are a class of macronutrients that play crucial roles in the body's structure, function, and energy metabolism. They are composed of molecules called fatty acids and are essential for various physiological processes. 

Chemical Structure:

• Fats are composed of carbon, hydrogen, and oxygen atoms, arranged in long chains of molecules called fatty acids.
• Fatty acids consist of a hydrocarbon chain with a carboxyl group (-COOH) at one end.
• Fats can be classified into different types based on the structure of their fatty acids, including saturated fats, unsaturated fats (monounsaturated and polyunsaturated), and trans fats.

Functions of Fats:

• Energy Storage: Fats serve as a concentrated source of energy, providing more than twice the calories per gram compared to carbohydrates or proteins. They are stored in adipose tissue throughout the body and can be broken down into fatty acids to fuel cellular metabolism.
• Cellular Structure: Fats are essential components of cell membranes, where they help maintain membrane integrity, fluidity, and permeability. Phospholipids, a type of lipid, form the structural basis of cell membranes.
• Insulation and Protection: Adipose tissue acts as insulation, helping to regulate body temperature and protect internal organs from mechanical shock and injury.
• Hormone Synthesis: Fats are precursors for the synthesis of steroid hormones, including cortisol, aldosterone, estrogen, progesterone, and testosterone. These hormones play important roles in metabolism, stress response, reproduction, and other physiological processes.
• Absorption of Fat-Soluble Vitamins: Fats facilitate the absorption of fat-soluble vitamins (A, D, E, and K) and other fat-soluble nutrients in the intestine. These vitamins are necessary for various functions, including vision, bone health, antioxidant activity, and blood clotting.

Dietary Sources of Fats:

• Fats are found naturally in a wide variety of foods, including:
  • Animal-based sources: Meat, poultry, fish, eggs, dairy products (butter, cheese, milk).
  • Plant-based sources: Nuts, seeds, avocados, olives, vegetable oils (olive oil, canola oil, sunflower oil, soybean oil).
• Processed and packaged foods may also contain added fats, such as hydrogenated oils, margarine, and fried foods.

Malnutrition

• Malnutrition refers to a condition where there is an imbalance between the nutrients a person's body needs and the nutrients they receive from their diet. It can involve undernutrition, overnutrition, or a combination of both, and it affects individuals across all age groups and socioeconomic backgrounds.