Lesson 2: Sourcing Molecules

Key Idea

Since the human body cannot create matter from nothing, it must gather supplies from the outside world. This constant need for materials makes the body dependent on its environment.

These materials enter the body as inputs through two main pathways: eating and breathing. These two activities are the primary ways we harvest the raw materials needed for life.

Key Idea

The specific molecules that cells need are found in different environmental sources. Food is the source of solid molecular building blocks, while air provides gaseous molecules.

To sustain cellular function, the body must effectively extract these molecules from both sources. This explains why we must eat and breathe regularly; we are constantly replenishing the molecular fuel our cells consume.

Key Idea

Food is a complex mixture of nutrients that the body processes to get what it needs. Specifically, food provides glucose and amino acids.

Glucose is a sugar molecule that acts as the body's primary fuel source.

Amino acids are the building blocks of proteins, used to repair damage and grow new structures. Both are derived from the digestion of the food we eat.