Carbohydrates: Fructose and Functions

Fructose and Carbohydrates

• Fructose is a component of sucrose and classified as a ketohexose, known for being twice as sweet as glucose.
• Carbohydrates, including sugars and starches, are polyhydroxy aldehydes or ketones, or compounds that can be hydrolyzed into them.
• Disaccharides comprise two monosaccharide units linked via glycosidic linkage, categorized into alpha and beta based on the linkage orientation.
• Monosaccharides such as glucose, fructose, and galactose combine to form disaccharides like sucrose (glucose + fructose), lactose (galactose + glucose), and maltose (glucose + glucose).
• Polysaccharides consist of three or more monosaccharides; examples include cellulose, starch, and glycogen.

Blood Types and Monosaccharides

• There are four human blood types: A, B, AB, and O, which are determined by specific monosaccharide combinations.
• Type A blood contains a monosaccharide unique to it, while type B includes an additional D-galactose unit, AB has both, and type O is a universal donor.

Polysaccharides

• Cellulose is structured from glucose units joined by 1-4 beta glycosidic linkages, providing rigidity and making it undigestible, thus constituting insoluble fiber.
• Starch, composed of glucose linked by alpha 1-4 glycosidic linkages, is digestible, found in corn, rice, wheat, and potatoes. It exists as amylose (unbranched) and amylopectin (branched).
• Glycogen is a storage polysaccharide in animals, similar in structure to amylopectin and highly branched, primarily stored in liver and muscles.

Lipids Overview

• Lipids are biomolecules soluble in organic solvents, insoluble in water, and characterized by diversity in structure and function.
• They serve as a major energy source for the body and are lighter than water.

Classification of Lipids

• Hydrolyzable lipids can be broken down into smaller molecules through hydrolysis and include waxes, triacylglycerols, and phospholipids.
• Non-hydrolyzable lipids cannot be cleaved by hydrolysis and include steroids and fat-soluble vitamins.
• Lipids can be categorized as simple (esters of fatty acids) or complex (contain additional molecules).

Essential Fatty Acids

• Essential fatty acids are those the body cannot produce, including alpha-linolenic acid (omega-3) and linoleic acid (omega-6).

Fatty Acid Structure

• Cis fatty acids have hydrogens on the same side of the double bond, creating a kink, while trans fatty acids have hydrogens on opposite sides, resembling saturated fat structure.

Phospholipids and Cell Membrane Structure

• Phospholipids, including phosphoacylglycerols, are key components of cell membranes, with a polar head and nonpolar tails.
• Cell membranes comprise proteins, cholesterol, and carbohydrates, forming glycolipids and glycoproteins to aid molecule transport.
• Integral proteins span the bilayer, while peripheral proteins are attached to one side, allowing molecules to pass through via facilitated transport.

Triacylglycerols and Hydrolysis

• Triacylglycerols can be either saturated (only saturated fatty acids) or unsaturated (contain at least one unsaturated fatty acid).
• The hydrolysis of triacylglycerols could involve soap synthesis, where metal salts of fatty acids are formed through saponification, resulting in heads soluble in water and tails soluble in oil.