Biochem (Carbs 3.0 & Lipids 1.0) PDF

1. Monosaccharides and Their Structural Sugar Alcohols Characteristics Reduction to sugar alcohols: The Pentose: Ribose is a pentose (5-carbon carbonyl group in a monosaccharide sugar)....

1. Monosaccharides and Their Structural Sugar Alcohols Characteristics Reduction to sugar alcohols: The Pentose: Ribose is a pentose (5-carbon carbonyl group in a monosaccharide sugar). (either an aldose or a ketose) is reduced Ketose: Fructose is a ketose (contains a to a hydroxyl group using hydrogen as ketone group). the reducing agent. Glucose & Galactose: Cyclic Forms ○ The product is the with 6-Membered Ring: Glucose and corresponding polyhydroxy galactose form 6-membered rings. alcohol - sugar alcohol. Fructose: Two Carbon Atoms Outside the Ring: Fructose has two carbon atoms Sorbitol outside its cyclic ring. - used as moisturizing agents in 2. Key Reactions of Monosaccharides foods and cosmetics and as a Oxidation sweetening agent in chewing Oxidation to acidic sugars gum - The redox chemistry of - is found in the plant world in monosaccharides is closely linked to the many berries and in cherries, alcohol and aldehyde functional groups plums, pears, apples, seaweed, present in them. and algae. - It is about 60 % as sweet as Three different types of acidic sugars sucrose (table sugar) and is used ○ Weak oxidizing agents such as in the manufacture of candies Tollens and Benedict’s solutions and as a sugar substitute for oxidize the aldehyde end to give diabetics. an aldonic acid. Many “sugar-free” products contain alcohols, ○ Reducing sugar is a such as sorbitol and xylitol carbohydrate that gives a positive test with Tollens and Glycoside Benedict’s solutions. ○ Aldaric Acid (Polyhydroxy Glycoside formation: Cyclic forms of dicarboxylic acid): Formed by monosaccharides are hemiacetals, they strong oxidizing agents that react with alcohols to form acetals: oxidize both ends of the ○ Monosaccharide acetals are monosaccharide. called glycoside A glycoside is an acetal formed from a Alduronic Acid cyclic monosaccharide by replacement - Produced when enzymatic oxidation of of the hemiacetal carbon —OH group the primary alcohol end of an with an —OR group: aldosterone such as glucose, without ○ A glycoside produced from oxidation of the aldehyde group glucose - glucoside ○ A glycoside produced from galactose – galactoside  ○ Glycosides exist in both Alpha and Beta forms Two monosaccharides can react to form disaccharide 3. Blood Types and Monosaccharides One monosaccharide act as a hemiacetal and other as alcohol (alcohol and ether - Human blood types (A, B, AB, O) are attached to the same carbon. determined by specific monosaccharides on red blood cells (D-galactose and its derivatives). 5. Disaccharides - A transfusion of the wrong blood type can cause the blood cells to form clumps Cellobiose - a potentially fatal reaction. - Intermediate in cellulose hydrolysis, - Type O is a universal donor; type AB is containing two β-D-glucose units linked a universal recipient. via β(1-4) bonds. - The biochemical basis for the various blood types involves monosaccharides Maltose present on plasma membranes of red - Digested by humans; contains α(1-4) blood cells. linkages. - The monosaccharides responsible for blood groups are D-galactose and its derivatives. Lactose 4. Phosphate Esters and Amino Sugars - principal carbohydrate in milk - Made of β-D-galactose and β-D-glucose Phosphate Ester Formation units; lactose intolerance occurs due to a - Hydroxyl groups of monosaccharides lack of lactase enzyme. react with inorganic acids to form stable - Human - 7%–8% lactose phosphate esters, important in - cow’s milk - 4%–5% lactose carbohydrate metabolism. - Lactose intolerance: a condition in which people lack the enzyme lactase needed to hydrolyze lactose to galactose Amino Sugar Formation and glucose. - Involves replacing a hydroxyl group - Lactase enzyme hydrolyzes β(1-4) with an amino group, vital in forming glycosidic linkages. polysaccharides like chitin. - Deficiency of lactase can be caused by a genetic defect, physiological decline  with age, or by injuries to intestinal mucosa. - When lactose is undigested it attracts water causing fullness, discomfort, cramping, nausea, and diarrhea. Bacterial fermentation of the lactose further along the intestinal tract produces acid (lactic acid) and gas, adding to the discomfort. “Human milk contains more lactose than does cow’s milk. Lactose intolerance is a condition In which people lack the enzyme lactase, which is needed to hydrolyze lactose to galactose and 6. Polysaccharides glucose” Sucrose (Table sugar) - are not sweet and do not show positive - Composed of glucose and fructose; not a tests with Tollen’s and Benedict’s reducing sugar due to its “head-to-head” solutions whereas monosaccharides are glycosidic linkage. sweet and show positive tests - The most abundant of all disaccharides - Limited water solubility and found in plants. - Examples: - It is produced commercially from the - Cellulose, starch in plants juice of sugar cane and sugar beets. - Glycogen in animals - Sugar cane contains up to 20% - Chitin in arthropods by mass sucrose - Sugar beets contain up to 17% Starch by mass sucrose A storage polysaccharide is a The Polymer Chain polysaccharide that is a storage form for Polymers monosaccharides and is used as an Many monosaccharide units bonded energy source in cells. with glycosidic linkages Starch: Two types: ○ Glucose is the monomeric unit Linear and branched, homo- and ○ Storage polysaccharide in plants hetero-polysaccharides ○ Two types of polysaccharidse isolated from starch: Amylose: Straight chain polymer - 15 - 20% of the starch and has α (1 4) glycosidic bonds Molecular Mass: 50,000 (up to 1000 glucose units)  Chitin - Similar to cellulose, with N-acetyl Amylopectin: amino derivative of glucose, providing ○ Branched chain polymer - 80 - rigidity to arthropod exoskeletons such 85 % of the starch α (14) as crabs, lobsters,insects,shrimp. glycosidic bond for straight chain and α (16) for branch Acidic Polysaccharides ○ Molecular Mass: 300,000 (up to 100,000 glucose units) - higher polysaccharides with a repeating than amylose disaccharide unit containing an amino ○ Human can hydrolyze alpha sugar and a sugar with a negative charge linkage but not beta linkage due to a sulfate or a carboxyl group. Storage polysaccharide in plants, made Structural polysaccharide present in of amylose (straight-chain) and connective tissue associated with joints, amylopectin (branched chain). cartilage, synovial fluids in animals and humans Glycogen ○ Primary function is lubrication - Storage polysaccharide in animals, necessary for joint movement highly branched, stored in liver and ○ These are heteropolysaccharides muscles. - have more than one type of - Contains only glucose units monosaccharide monomer - Branched chain polymer – a (14) present. glycosidic bonds in straight chains and a Examples: (16) in branches ○ Hyaluronic acid - Molecular Mass: 3,000,000 (up to ○ Heparin 1,000,000 glucose units) - Found in connective tissues, such as - Three times more highly branched than hyaluronic acid (joint lubrication) and amylopectin in starch heparin (anticoagulant). - Excess glucose in blood stored in the form of glycogen Hyaluronic acid: - Alternating residues of Cellulose N-acetyl-b-D-glucosamine and - Linear homopolysaccharide with β(1-4) D-glucuronic acid. glycosidic bond linkages; indigestible - Highly viscous - serve as lubricants in by humans but serves as dietary fiber. the fluid of joints and part vitreous - Animals can digest cellulose because humor of the eye. they have bacteria in their guts to hydrolyze cellulose Heparin: - Dietary fiber in food- easily absorbs - An anticoagulant-prevents blood clots. water and results in softer stools - Polysaccharide with 15–90 disaccharide - 20-35 g of dietary fiber is desired residues per chain. everyday  Lipids 1. Definition and Characteristics of Lipids - Lipids are organic compounds found in living organisms that are insoluble in water but soluble in non-polar organic solvents. - Lipids do not have common structural features like other biomolecules; they are classified based: A. biochemical function A glycolipid is a lipid molecule that has B. saponification. one or more carbohydrate (or carbohydrate derivative) units 2. Classification of Lipids covalently bonded to it. A glycoprotein is a protein molecule Energy-Storage Lipids: Triacylglycerols. that has one or more carbohydrate (or Membrane Lipids: Phospholipids, carbohydrate derivative) units sphingoglycolipids, and cholesterol. covalently bonded to it. Emulsification Lipids: Bile acids. Chemical Messenger Lipids: Steroid hormones, eicosanoids. Protective-Coating Lipids: Biological 7. Nutrition and Glycemic Index waxes. - Carbohydrates make up over 50% of 3. Saponification Classification most diets. 60% in a balanced dietary food Saponification reaction - They can be classified into: - Hydrolysis reaction that occurs in a a. Simple Carbs:Dietary Monosaccharides basic solution or disaccharides, typically sweet (e.g., sucrose). a. Saponifiable Lipids b. Complex Carbs: Dietary - Include triacylglycerols, phospholipids, Polysaccharides like starch and sphingoglycolipids, cholesterol, and cellulose, not sweet. biological waxes (can undergo hydrolysis in basic solution). Glycemic Foods - Glycemic Index (GI): Measures how b. Non-saponifiable Lipids quickly carbs are digested, how high - Include bile acids, steroid hormones, blood glucose rises, and how quickly and eicosanoids (cannot undergo levels return to normal. Foods are rated hydrolysis in basic solution). based on their GI. Structural Diversity of Lipids & Formulas Lipids exhibit structural diversity Some are esters, some are amides, and some are alcohols (acyclic, cyclic, and polycyclic) Unsaturated Fatty Acids: - Monounsaturated Fatty Acids: One carbon-carbon double bond. 4. Fatty Acids - Carboxylic acids with linear (unbranched) carbon chain - Fatty acids are naturally occuring monocarboxylic acids Even # of Carbon atoms: Long chain fatty acids: C12 - C26 Polyunsaturated Fatty Acids (PUFAs): Medium chain fatty acids: C8 – C10 - A polyunsaturated fatty acid is a fatty Short-chain fatty acids: C4 – C6 acid with a carbon chain in which two or Two Types: more carbon–carbon double bonds are Saturated - all C-C bonds are single bonds present. Unsaturated - Up to six double bonds are found in Monounsaturated: one C=C bond biochemically important PUFAs. Polyunsaturated: 2 or more C=C bonds present - up to six double bonds are present in fatty acids Two types of unsaturated fatty acids: a. Omega (ω)-3 fatty acids - An Saturated Fatty Acids unsaturated fatty acid with its endmost Fatty acids with a carbon chain in which all C–C double bond three carbon atoms away bonds are single bonds from its methyl end. Numbering starts from the end of –COOH group Consider the structural notations for palmitic acid:  b. Omega(ω)-6 fatty acid is an unsaturated fatty acid with its endmost double bond six carbon atoms away from its methyl end. Most omega 6: safflower Most omega 3: fish Selected Unsaturated Fatty Acids of Biological Importance Numbering starts from the other end of COOH See structural notation: it indicates number of C atoms E.g., 18:2 – 18 carbons, 2 double bonds Omega Acids Essential Fatty Acids: must be part of diet Linolenic Acid (Omega-3) and Linoleic Acid (Omega-6) must be obtained from 5. Physical Properties of Fatty Acids the diet. Deficiency in linoleic acid can cause Water Solubility skin irritation, infections, and liver - Short-chain fatty acids have some abnormalities. solubility in water, while long-chain American Diet fatty acids are insoluble. Sufficient in omega 6 fatty acids Deficient in omega 3 fatty acids Melting Point: Fish - good source for omega 3 fatty - Dependent on the length of the carbon acids chain and the degree of unsaturation High rate of heart disease may be due (more double bonds lower the melting to imbalance in omega 3 and 6 fatty point). acids - More unsaturation leads to less packing Ideal ratio: Omega 6 : Omega 3 (4 - 10 and a lower melting point, meaning they g: 1g) are likely liquid at room temperature. Space-Filling Molecules Fats The number of bends in a fatty acid chain - Predominantly saturated, solid or increase as the number of double bonds increase semisolid at room temperature, sourced Less packing occurs from animals. Melting point is lower Tend to be liquids at room temperature Oils - Predominantly unsaturated, liquid at room temperature, sourced from plants and fish. Triacylglycerols are more efficient at storing energy than glycogen. 7. Membrane Lipids - Lipids like phospholipids, sphingoglycolipids, and cholesterol are critical for membrane structure and function. 6. Energy-Storage Lipids: Triacylglycerols - Phospholipids: Form the basic structure With the notable exception of nerve cells, human of cell membranes. cells store small amounts of energy providing - Sphingoglycolipids and cholesterol: materials: Play roles in membrane fluidity and The most widespread energy storage material signaling. -carbohydrate glycogen Present in small amounts 8. Dietary Considerations Triacylglycerols/adipose tissue (fats and oils) - Excessive intake of fats and oils, - the main storage form of energy in particularly in the American diet, is humans. linked to heart disease and cancers. Simple Triacylglycerols “Good Fats” vs “Bad Fats”: - Formed by esterifying glycerol with Good Fats three identical fatty acids (rare). - Monounsaturated fats (e.g., olive oil), omega-3, and omega-6 polyunsaturated Mixed Triacylglycerols: fats. - A triester formed from the esterification of glycerol with more than one kind of Bad Fats fatty acid - Saturated fats, trans-monounsaturated In nature mostly mixed triacylglycerols are fats. found and are different even from the same Polyunsaturated fats can be both “good source depending on the feed, e.g., corn, peanut fats” and “bad fats” and wheat -fed cows have different Omega 3 and 6 are important “good triacylglycerols fats”  Deficiencies of above two acids may result in skin redness, infections and dehydration likely Omega-3 Fatty Acids (found in fish) are crucial and liver abnormalities may develop for heart health, but the typical American diet is deficient in them. The ideal ratio of omega-6 to omega-3 fatty acids is between 4:1 and 10:1. 9. Reactions of Lipids A. Saponification: A hydrolysis reaction in basic conditions that produces glycerol and soap from triacylglycerols. B. Hydrogenation: The process of converting unsaturated fats into saturated fats by adding hydrogen, which can produce trans fats. 10. Essential Functions of Lipids 1. Emulsification Lipids: Bile acids help emulsify fats for digestion. 2. Chemical Messengers: Steroid hormones (e.g., testosterone, estrogen) and eicosanoids (inflammatory mediators) are lipid-derived. 3. Protective Coatings: Biological waxes protect plants and animals from water loss. Essential Fatty Acids Fatty acids that must be obtained from dietary sources – are not synthesized within the body Two most important essential fatty acids are: Linoleic acid (18:2) - omega 6 Linolenic acid (18:3) - omega 3 Both are needed for: A. Proper membrane structure B. Serve as starting materials for the production of several nutritionally important longer-chain omega-6 and omega-3 fatty acids