Biological Molecules

Overview

Biological molecules, also known as biomolecules, are essential compounds that form the basis of life. They include carbohydrates, lipids (fats), proteins, and nucleic acids. Each class of biomolecule has unique structural features and functions that are critical for cellular processes and the physiology of organisms.

• Carbohydrates: Provide energy and structural support.

• Fats (Lipids): Store energy, insulate, and form cell membranes.

• Proteins: Serve as enzymes, structural components, and signaling molecules.

• Nucleic acids: Store and transmit genetic information.

Characteristics of Biological Molecules

Key Features

• Principal Elements: Most biomolecules are composed primarily of carbon (C), hydrogen (H), oxygen (O), nitrogen (N), and sometimes phosphorus (P) and sulfur (S).

• Ratio of Various Elements: The proportion of these elements varies by molecule type (e.g., carbohydrates have a 1:2:1 ratio of C:H:O).

• Special Functional Groups: Specific groups of atoms within molecules confer unique chemical properties and reactivity.

Functional Groups

Common Functional Groups in Biomolecules

• Hydroxyl (-OH): Found in alcohols; increases solubility in water.

• Carbonyl (C=O): Present in aldehydes and ketones; involved in energy metabolism.

• Carboxyl (-COOH): Characteristic of carboxylic acids; imparts acidic properties.

• Amino (-NH2): Found in amines and amino acids; acts as a base.

• Phosphate (-H2PO4): Key in organic phosphates; important in energy transfer (e.g., ATP).

• Sulfhydryl (-SH): Present in thiols; forms disulfide bonds in proteins.

Monomers and Polymers

Building Blocks of Biomolecules

Biological molecules are often polymers, made by linking smaller subunits called monomers through covalent bonds. The process of joining monomers is called dehydration synthesis, while breaking polymers into monomers is called hydrolysis.

• Monomer: A single subunit (e.g., glucose, amino acid, nucleotide).

• Polymer: A chain of monomers (e.g., starch, protein, DNA).

• Dehydration Synthesis: Removal of water to form a covalent bond between monomers.

• Hydrolysis: Addition of water to break covalent bonds in polymers.

Dehydration Synthesis Example

Formation of sucrose from glucose and fructose:

• Glucose () + Fructose () → Sucrose () + Water ()

Equation:

Hydrolysis Example

Breakdown of sucrose into glucose and fructose:

• Sucrose () + Water () → Glucose () + Fructose ()

Equation:

Summary Table: Major Biological Molecules

Additional info:

• Understanding the structure and function of biological molecules is foundational for studying anatomy and physiology, as these molecules are involved in all cellular processes.

• Functional groups determine the chemical reactivity and interactions of biomolecules, influencing metabolism and physiological responses.

• Dehydration synthesis and hydrolysis are central to the formation and breakdown of macromolecules in living organisms.