Chapter 1: Introduction to Macromolecules and Lipids

Focus on the structure, size, and shape of macromolecules (proteins, lipids, carbohydrates, and nucleotides).
Understanding how these structures relate to metabolism.
Connection between macromolecules and cellular context.

Definition: Macronutrients that are water-insoluble, often oily or greasy.
Composition: Primarily composed of fatty acids; however, not all lipids contain fatty acids (e.g., steroids).

Energy Storage: Serve as the main storage form of energy in animals (animal fats).
- Fatty acids in lipids are energy dense compared to glucose (more energy per carbon).
Structural Components: Essential in forming cell membranes (polar lipids).
Hormone Production: Some lipids act as steroid hormones (cholesterol derivatives).
Transportation: Lipoproteins help transport water-insoluble lipids in the circulation.

Hydrophilic Head: Contains a carboxylic acid group.
Hydrophobic Tail: Long hydrocarbon chain.
Types of Fatty Acids: Saturated (no double bonds) and unsaturated (one or more double bonds).

Structure: Composed of glycerol and three fatty acids.
- Formed through ester bonds between glycerol (an alcohol) and fatty acids.
Storage: Main form of fat storage in adipocytes (fat cells).
Hydrophobic Properties: Completely non-polar, thus rarely found in cell membranes.
Hydrolysis: Ester bonds can be hydrolyzed to release fatty acids when energy is needed.

Phospholipids: Composed of glycerol, two fatty acids, and an inorganic phosphate group.
- Amphipathic nature allows them to form lipid bilayers in cell membranes.
- Polar head (hydrophilic) interacts with water, while hydrophobic tails face inward.
Sphingolipids: Similar to phospholipids but consist of sphingosine and one fatty acid.
Steroids: Characterized by fused ring structures, cholesterol being a primary example.
- Serve as precursors for steroid hormones.
Lipoproteins: Complexes of lipids and proteins that transport lipids in the blood.
- Four classes based on density: chylomicrons, very low-density lipoproteins (VLDLs), low-density lipoproteins (LDLs), and high-density lipoproteins (HDLs).

Composition: Esters of fatty acids and long-chain alcohols.
Functions: Serve various roles such as lubrication and waterproofing (e.g., feathers, skin).

Arise from the hydrogenation of unsaturated fats, altering their structure.
Linked to negative health effects by influencing lipoprotein profiles, potentially increasing heart disease risk.

Understand the diverse roles and structures of macromolecules, particularly lipids, in biological systems.
Recognize the importance of the amphipathic properties of phospholipids in forming cellular membranes and lipoprotein functions in lipid transport.
Note the health implications of dietary fats, particularly trans fats.