Chemical Basis of Life

Chapter 4

The Chemical Basis of Life

Introduction

• Your body is an elaborate chemical system.

• Chemical signals between brain less enable your mind to understand what you see.

• You nourish those cells with chemicals that are obtained from food.

• Life is all about chemicals and how they interact

Concept 4.1

Life requires about 25 chemical elements

Elements

• Humans and other organisms are examples of matter.

Matter: Anything that occupies space and has mass. (Physical things)

• The various forms of matter are composed of one or more chemical elements.

Element: A pure substance that cannot be broken down into smaller substances by chemical means

• There are 25 elements are essential to life. Four of these elements are Oxygen (O), Carbon (C), Hydrogen (H), and Nitrogen (N). These make up about 96% of the living matter in your body. Calcium (CA), Phosphorus (P), Potassium (K), sulfur (S), and a few other elements account for most of the remaining 4%.

Trace Elements: elements that make up less that 0.01 percent of your body mass are nevertheless critical to your health.

Compounds

• Most elements can interact with other elements forming complex types of matter called compounds.

Compound: A substance containing two or more elements that are chemically combined in a fixed ratio.

• Compounds properties may differ greatly from those of its components.

• Though simple compounds like sodium chloride and water play important roles in living things, most