Atoms form molecules through bonding.

• 2.1 Everything is made of atoms.
• 2.2 An atom’s electrons determine whether (and how) the atom will bond with other atoms.
• 2.3 Atoms can bond together to form molecules or compounds.

Water has features that enable it to support all life.

• 2.4 Hydrogen bonds make water cohesive.
• 2.5 Water has unusual properties that make it critical to life.
• 2.6 Living systems are highly sensitive to acidic and basic conditions.
• 2.7 This is how we do it: Do anti-acid drugs impair digestion and increase the risk of food allergies?

Carbohydrates are fuel for living machines.

• 2.8 Carbohydrates include macromolecules that function as fuel.
• 2.9 Glucose provides energy for the body’s cells.
• 2.10 Many complex carbohydrates are time-release packets of energy.
• 2.11 Not all carbohydrates are digestible.

Lipids store energy for a rainy day.

• 2.12 Lipids are macromolecules with several functions, including energy storage.
• 2.13 Fats are tasty molecules too plentiful in our diets.
• 2.14 Cholesterol and phospholipids are used to build sex hormones and membranes.

Proteins are versatile macromolecules that serve as building blocks.

• 2.15 Proteins are bodybuilding macromolecules.
• 2.16 Proteins are an essential dietary component.
• 2.17 A protein’s function is influenced by its three-dimensional shape.
• 2.18 Enzymes are proteins that speed up chemical reactions.
• 2.19 Enzymes regulate reactions in several ways (but malformed enzymes can cause problems).

Nucleic acids store information on how to build and run a body.

• 2.20 Nucleic acids are macromolecules that store information.
• 2.21 DNA holds the genetic information to build an organism.
• 2.22 RNA is a universal translator, reading DNA and directing protein production.