illustrations

Genetics is the study of the organization, expression, and transfer of heritable information. The ability for information to pass from generation to generation requires a mechanism. Living organisms use DNA. DNA is a chain, or polymer, of nucleic acids. Individual polymers of DNA can contain hundreds of millions of nucleic acid molecules. These long DNA strands are called chromosomes. The order of the individual nucleic acids along the chain contains information organisms used for growth and reproduction.

A wave is a movement or oscillation that spreads from a defined point, moving energy as it progresses.

Scientist use a standard set of terminology to describe the feature of waves. The following illustration shows a cross-section through a transverse wave. Use the switches below the main window to label the features:

Our ability to see and make sense of the world with our eyes depends on the reflective properties of light. Without reflection, we would only see luminous objects like the sun, light bulbs, and computer screens.

The light rays that allow us to see non-luminous objects such as our hands, the floor, and the people around us are lit by light rays that travel from a light source to the object and then bounce off the object towards our eyes.

Every sound we hear, every photon of light that hits our eyes, the movement of grass blown by the wind and the regular beat of the tides are all examples of waves. They are all around us.  Visible, physical waves such as those we see when a rock is thrown into water are what many people think about when they first began to think about waves. These waves have distinct properties specific to their type but also exhibit characteristics in common with more abstract waves such as sound waves and light (electromagnetic) waves.