3.7 Chapter 3 Summary

Synthesis of Biological Macromolecules:

Biological macromolecules are assembled through dehydration synthesis reactions, which link monomers by removing water. Polymers can be broken down into monomers through hydrolysis, which adds water. Enzymes (a type of protein) catalyze both reactions, aiding in the formation and breakdown of carbohydrates, lipids, proteins, and nucleic acids. These processes are essential for metabolism, nutrient absorption, and cellular function.

Carbohydrate Structure and Function:

Carbohydrates are macromolecules composed of carbon, hydrogen, and oxygen in a 1:2:1 ratio. They provide energy and serve as structural components in cells. Monomers of carbohydrate are monosaccharides (simple sugars). These monomers can form larger molecules classified as disaccharides (two linked monosaccharides) and polysaccharides (long chains of monosaccharides). Glucose is a key energy source, while polysaccharides like starch and glycogen serve as energy storage in plants and animals respectively. Meanwhile, cellulose is a key structural molecule in plants.

Nucleic Acid Structure and Function:

Nucleic acids, including DNA and RNA, store and transmit genetic information. DNA contains the genetic blueprint, while RNA plays a role in guiding protein synthesis. Both are made of nucleotides, which consist of a nitrogenous base, a sugar (deoxyribose in DNA, ribose in RNA), and phosphate groups. DNA forms a double helix with complementary base pairing (A pairs with T, C with G), while RNA is typically single-stranded and uses uracil (U) instead of thymine.

Protein Structure and Function:

Proteins are essential macromolecules with diverse functions, including structural support, catalysis, transport, and defense. They consist of amino acids linked by peptide bonds. Amino acids are made up of carbon, oxygen, hydrogen and nitrogen. The sequence of amino acids determines the protein’s shape and function. Proteins have four structural levels: primary (amino acid sequence), secondary (alpha-helices and beta-sheets), tertiary (three-dimensional folding), and quaternary (multiple polypeptide chains). Their specific shapes allow them to bind other molecules, making them highly versatile.

Lipid Structure and Function:

Lipids are hydrophobic molecules composed mainly of hydrocarbons (C-H). They serve as long-term energy storage, provide insulation, and form cellular membranes. The four main types of lipids are fats, oils, waxes, phospholipids, and steroids. Most fats (except for steroids) consist of glycerol and fatty acids, which can be saturated (single bonds) or unsaturated (one or more double bonds). Saturated fats are solid at room temperature, while unsaturated fats are liquid. Steroids play a role in hormone production.

Summary was initially generated by ChatGPT then modified by the author.