C2.3 Carbohydrates and Lipids

This section provides a comprehensive overview of carbohydrates and lipids, two major classes of biomolecules. The discussion begins with carbohydrates, explaining their classification into monosaccharides, disaccharides, and polysaccharides.

Definition: Carbohydrates are organic molecules composed of carbon, hydrogen, and oxygen, typically with a 2:1 ratio of hydrogen to oxygen.

The section includes a detailed table listing various carbohydrates, their monomers, and their biological uses. This information is crucial for IB Biology HL students to understand the diversity and functions of carbohydrates in living systems.

Example: Sucrose, a disaccharide composed of glucose and fructose, is used to transport energy from leaves to storage organs in plants.

Polysaccharides are given special attention, with a focus on starch, glycogen, and cellulose. The properties of these complex carbohydrates are discussed, including their compact nature, insolubility, and ease of enzymatic hydrolysis.

Highlight: The structural differences between alpha and beta glucose are crucial for understanding the diverse functions of polysaccharides in nature.

The section begins to touch on the industrial applications of starch, setting the stage for a broader discussion of the practical uses of carbohydrates in various fields.

This detailed exploration of carbohydrates provides IB Biology HL students with a solid foundation for understanding more complex biochemical processes and the role of these molecules in living organisms.

C2.1 Molecules to Metabolism

This section introduces the fundamental concepts of molecular biology, focusing on the structure and properties of key biological molecules. The carbon atom's unique ability to form four covalent bonds is highlighted, explaining its central role in organic compounds.

Definition: Molecular biology is the study of the composition, structure, and interactions of cellular molecules.

The chapter delves into the structures of carbohydrates, lipids, proteins, and nucleic acids, providing required diagrams for ribose, deoxyribose, and glucose molecules. These diagrams are essential for understanding the structural differences between various biomolecules.

Highlight: The section emphasizes the importance of understanding molecular structures, as they directly relate to the functions of these biomolecules in living systems.

Metabolism is introduced as the sum of all reactions in our body, with a focus on anabolism and catabolism. These processes are explained with specific examples, such as the synthesis of maltose from glucose (anabolism) and the breakdown of lactose into glucose and galactose (catabolism).

Example: Anabolism example: glucose + glucose → maltose (glycosidic bond formation) Example: Catabolism example: lactose → glucose + galactose (glycosidic bond hydrolysis)

This comprehensive overview sets the stage for a deeper understanding of biochemical processes in living organisms, crucial for IB Biology HL students.