Biochemistry! PDF

1. Carbohydrates Carbohydrates are a crucial energy source, with di erent types providing unique bene ts: Simple Carbohydrates: Include monosaccharides (e.g., glucose, fructose) and disaccharides (e.g., sucrose, lactose). These are quickly absorbed, causing rapid spikes in blood sugar but lacking i...

1. Carbohydrates Carbohydrates are a crucial energy source, with di erent types providing unique bene ts: Simple Carbohydrates: Include monosaccharides (e.g., glucose, fructose) and disaccharides (e.g., sucrose, lactose). These are quickly absorbed, causing rapid spikes in blood sugar but lacking in nutrients. Complex Carbohydrates: Include polysaccharides (e.g., starch, glycogen). Found in whole grains and vegetables, they o er sustained energy release and dietary ber, which aids digestion and stabilizes blood sugar. Metabolism: Carbohydrate digestion begins in the mouth with salivary amylase, breaking polysaccharides into smaller molecules. In the small intestine, enzymes like lactase and sucrase further break down carbohydrates into monosaccharides for absorption. Glucose is primarily stored as glycogen in the liver and muscles, entering metabolic pathways like glycolysis, the TCA cycle, and electron transport chain to produce ATP. Fiber: Divided into soluble (e.g., pectin) and insoluble (e.g., cellulose), ber helps with satiety, blood sugar regulation, and cholesterol reduction. Recommended intake is 25-35 grams per day. 2. Proteins Proteins are fundamental to body structure and function, broken down into amino acids for diverse roles: Amino Acids: Divided into essential, non-essential, and conditionally essential types. Essential amino acids must be obtained from the diet, while non-essential ones are synthesized by the body. Digestion: Proteins are denatured in the stomach by pepsin, then broken into peptides and amino acids in the small intestine. Absorbed amino acids are used for synthesizing body proteins, enzymes, and hormones. In times of energy shortage, amino acids can undergo gluconeogenesis (glucose formation) or ketogenesis (ketone body formation). Amino Acid Metabolism: Includes deamination (removal of amino groups) and transamination (transfer of amino groups). The amino group is converted to urea and excreted, while the carbon skeleton enters various metabolic pathways. 3. Fats/Lipids Fats serve as concentrated energy storage and structural components of cells: Types of Fats: Include triglycerides, phospholipids, and cholesterol. Triglycerides are the primary stored fat, while phospholipids form cell membranes and cholesterol contributes to steroid hormone synthesis. Saturated vs. Unsaturated: Saturated fats (no double bonds) are mainly found in animal products, while unsaturated fats (one or more double bonds) are in plant sources and are considered healthier. Digestion and Absorption: Bile emulsi es fats in the small intestine, enabling pancreatic lipase to break triglycerides into fatty acids and monoglycerides for absorption. Absorbed fats are packaged into chylomicrons, which transport fats through the lymphatic system. Metabolism: Fat metabolism produces ketone bodies during prolonged fasting or low-carbohydrate intake, providing energy to cells. Fats “burn in the re of carbohydrates,” meaning they require carbohydrate metabolism intermediates to fully oxidize in the TCA cycle. 4. Vitamins Vitamins are essential organic molecules functioning mainly as coenzymes: B-Complex Vitamins: Important for energy production and metabolism. For example, thiamin (B1) supports glucose metabolism, and de ciencies can cause disorders like beriberi. Other B vitamins, such as niacin (B3) and biotin (B7), contribute to the metabolism of fats, proteins, and carbohydrates. Vitamin C: Essential for collagen synthesis and acts as an antioxidant, supporting immune health and skin elasticity. Vitamin A: Crucial for vision; it participates in the visual cycle by binding with opsin in the retina. It also supports immune function and growth. Vitamin D: Regulates calcium absorption and bone health by converting to its active form, calcitriol, which enhances calcium and phosphorus uptake in the intestine. Vitamin E: A potent antioxidant, it protects cells from free radical damage and supports immune health. Vitamin K: Vital for blood clotting and bone health through activation of proteins that bind calcium. 5. Minerals Minerals are inorganic elements required for various physiological functions: Calcium and Phosphorus: Critical for bone health, with calcium levels tightly regulated by parathyroid hormone (PTH) and vitamin D. Phosphorus is important for energy storage (as ATP) and cellular signaling. Sodium and Potassium: Essential for uid balance, nerve transmission, and muscle function. Sodium predominates outside cells, while potassium is concentrated inside cells, creating the resting membrane potential. Iron: Necessary for oxygen transport in red blood cells. Its absorption is regulated by the hormone hepcidin; excess iron can be toxic, so the body has limited iron excretion pathways. Zinc: Supports immune function, cellular repair, and enzyme activation. It is absorbed in the gut and recycled between organs, with primary excretion through the intestines. Iodine: Required for thyroid hormone synthesis, which regulates metabolism. It is absorbed and transported to the thyroid gland, with excess excreted via urine. Magnesium: Important for ATP production, nerve function, and blood sugar regulation. It is absorbed both passively and actively in the intestines. This comprehensive guide integrates macronutrient and micronutrient biochemistry, focusing on how each nutrient contributes to overall metabolic processes essential for maintaining human health.