Life: Levels of Organization

Life is organized into different levels the single living thing: the organism •organ systems •organs •tissues •cells •organelles •molecules •atoms

Organism A living thing animal plant animal cabbage rabbit human

Organ systems Organ systems have a specific job or function For example: the digestive system

stomach Organs small intestine Organs are structures that have a function or job in an organ system

Tissue Organs are built from tissues A tissue is made from a group of cells that have a special job Example: muscle tissue

Cell A cell is the most basic unit of life The cell’s structure depends on the cell’s job or function All cells have certain things in common: Cell membrane, DNA, RNA, organelles

DNA is a large molecule that is in most cells A molecule is a group of atoms joined together by chemical bonds DNA controls how the cell works and the cell’s job DNA has a special structure or shape which is called a double helix

A molecule is made of atoms connected by chemical bonds A simple molecule made of 3 atoms: A chemical bond is the energy that keeps two or more atoms connected An atom is the smallest piece of matter that cannot be broken down and still keeps its properties Properties of matter include mass, density, freezing point, melting point and more

An atom is the smallest piece of matter that keeps its properties In the middle of the atom is the nucleus that is made of protons and neutrons Electrons surround the nucleus in a cloud