Hierarchy of Organization

QUARKS & GLUONS…Different types of quarks and gluons form neutrons and protons.

SUBATOMIC PARTICLES…Protons and neutrons form the atomic nucleus (diameter =10^-13m), electrons orbit the nucleus in orbitals.

ATOMS…The smallest particle of an element that has that element's properties, from Greek word atomos meaning indivisible. (diameter = 2-4 angstroms, 10^-10m)

MOLECULES…A particle consisting of 2 or more atoms bonded together. Some molecules can be very large, consisting of hundreds of atoms.

ORGANELLES…Meaning "little organs" these specialized structures are found within cells. Cellular nucleus, ribosome, mitochondria, chloroplasts, various vacuoles, cellular and nuclear membrane are examples of organelles.

CELLS…The fundamental unit (or building block) of all living things. There are approximately 100 trillion cells in our bodies, most less than .1 millimeters in width.

TISSUES….Specialized collections of cells; muscle, bone, nervous, and connective tissues for example

ORGANS…Specialized structures in the body like the heart, brain, liver, and kidney.

ORGAN SYSTEMS…Collections of organs with a similar body function such as the nervous system (brain/spinal cord, sensory organs, peripheral nerves) or circulatory system (blood, heart, arteries, veins, capillaries).

ORGANISM…An individual composed of a collection of organ systems

POPULATIONS…Collections of similar organisms

BIOSPHERE…The total of all living things on our planet

SOLAR SYSTEM…The collection of our sun and its orbiting planets and accompanying "moons". Diameter of solar systems are often measured in light years. (speed of light, c =186,000 miles per second!)

GALAXY…Billions of stars and accompanying solar systems make up a galaxy

UNIVERSE…Astronomers estimate the universe may contain 100,000,000,000 galaxies!