Polysaccharides, Lipids and Fatty Acids

• Study notes for Carolina Leyva Cázares, dated February 10, 2025.

Polysaccharides

• They form cellular structures.
• Serve as an energy reserve for the cell.
• Are part of the plasma membrane.
• Their degradation provides 4 kcal/gr.

Characteristics of Monosaccharides, Disaccharides and Polysaccharides

• Monosaccharides are formed by a single molecule, are simple sugars, soluble in water, sweet, and white.
• Disaccharides are formed by two monosaccharides linked by a glycosidic bond; they are soluble in water and sweet.
• Polysaccharides are formed by the union of numerous glucoses and are insoluble in water.

Lipids

• Organic biomolecules mainly composed of carbon, hydrogen, and oxygen, with a low oxygen content.
• Insoluble in water but soluble in organic solvents.
• Formed by glycerol (alcohol) and fatty acids.

Fatty Acids

• Formed by long chains of carbon atoms (in even numbers).
• Saturated with hydrogen and a carboxyl functional group (-COOH) at one end, making them hydrophobic.

Types of Fatty acids

• Saturated: have single bonds in the carbon chain.

• Unsaturated: have at least one double bond and are called monounsaturated or can have two or more (polyunsaturated).

• Study notes for Carolina Leyva Cázares, dated February 11, 2025.

Functions of a substance

• Serves as an energy reserve, providing 9 kcal/gr.
• Protective covering.
• Cholesterol is a precursor of some hormones, vitamins, and bile salts.
• Component in brain function.
• Structural component in cell membranes.
• Important in blood coagulation.
• Thermal insulator.

Proteins

• Organic biomolecules with high molecular weight composed of carbon (C), hydrogen (H), oxygen (O), nitrogen (N), phosphorus (P), sulfur (S), and, to some frequency, iron (Fe) and magnesium (Mg).
• Constitute the majority of the dry weight of cells and are the final product of protein synthesis, based on the genetic information of each cell.
• Long chains formed by a large number of subunits called amino acids. Amino acids are formed by an asymmetric carbon linked to an amino group (-NH2), a carboxyl group (-COOH), and a group R, giving each amino acid its particular characteristics.
• A large number of amino acids exist in nature, but only twenty form proteins; nine of these cannot be synthesized by cells, so they must be ingested in food and are known as essential amino acids; the rest are non-essential.

Types of Proteins

• Fibrous: Have an elongated and compact structure in the form of fibers or very resistant sheets, with very high molecular weights and insoluble in water; examples: collagen, elastin, and keratin.