Lesson 9.2: Carbon-based molecules are life's building blocks

Lesson Focus

Carbon-based molecules are the essential building blocks of life. We will explore the four major types and discover how their unique structures determine their vital functions in all living things, from energy storage to genetic information.

Learning Objectives

• Understand the functions of carbohydrates and lipids, which provide energy and structure for living things.
• Describe the diverse structures and many functions of proteins, from building tissues to controlling chemical reactions.
• Explain how nucleic acids, like DNA, store and transmit the genetic instructions needed to build proteins.

Phenomenon: Living things need energy.

Cause: Cells get energy from food molecules.

Mechanism: Carbohydrates like sugar and starch are the main source. Cells break down glucose (C₆H₁₂O₆) to release chemical energy.

Phenomenon: Organisms need to save energy for later.

Cause: Lipids (fats and oils) are better for long-term storage.

Mechanism: Made of fatty acid chains, they hold twice the energy of carbs. They also form cell membranes (phospholipids).

Phenomenon: Bodies must perform many tasks like building muscle.

Cause: Proteins are the versatile 'worker' molecules.

Mechanism: They are chains of amino acids. The specific sequence of 20 types of amino acids determines a protein's 3-D shape.

Phenomenon: Body reactions must happen fast.

Cause: Many reactions are too slow on their own.

Mechanism: Enzymes, a special type of protein, act as catalysts. Their specific shape fits with molecules to accelerate reactions.

Phenomenon: Cells need a 'blueprint' to build proteins correctly.

Cause: Nucleic acids like DNA store this information.

Mechanism: The sequence of four bases (A,T,C,G) is a code. Each three-base sequence codes for one amino acid.