The Organization of Living Things Hierarchy of Organisms

Key Concept As multicellular organisms develop, their cells differentiate (change & separate) and form levels of organization Why it Matters: so Humans (we are multicellular) can have different kinds of cells, tissues, organs, and organ systems

Unicellular Organisms “uni-” = one Prokaryotes are unicellular organisms Some algae, some protists, and some eukaryotes (yeasts), are unicellular Can still do everything they need to stay alive Benefits over multicellular organisms: Need fewer resources Can live in harsher conditions

Multicellular Organisms “multi-” = more than one Plants, animals, some protists, and most fungi are multicellular Start as a single cell  many cells  cells differentiate (change) into different types of cells  cells group together

Multicellular Characteristics Larger size = have less predators and have more options of things to eat Longer life – organism will continue to live even if a single cell dies Specialization – each type of cell has a specific job, making the organism more efficient

Levels of Organization 1st Level: Cells 2nd Level: Tissues 3rd Level: Organs 4th Level: Organ Systems Cells  Tissues  Organs  Organ Systems

Level 1 : Cells Cells can be specialized (have a certain function) Function = job Function is related to the cell structure Structure = how parts of the cell are put together Shape Material it’s made from Structure of a brain cell is different from muscle cell

Level 2: Tissues Tissue = group of cells that work together to do a specific job Ex: Heart muscle tissue is made of heart muscle cells Animals have 4 types of tissue: nerve, muscle, connective, protective Plants have 3 types of tissue : transport, protective, ground

Four Types of Tissues Nerve Muscle Connective Protective or Epithelial Conducts impulses to and from body organs via neurons Muscle Body movement Smooth muscle found on organ walls and blood vessels Skeletal muscle found as large body muscles and attached to bones Cardiac muscle found in the heart wall Connective Cushions and supports Stores nutrients Cartilage, Bone, Blood, Adipose (fat) Protective or Epithelial Skin, lining of organs Acts as filters-the kidneys Secretes as glands

Nerve Muscle Connective Epithelial

Level 3: Organs Organ = structure that is made up of 2 or more tissues working together to get a specific job done Ex: Stomach – muscle tissue moves food, special tissues make chemicals to digest food, connective tissue holds stomach together, nervous tissue sends messages back and forth between the stomach and brain

Level 4: Organ Systems Organ system = group of organs working together to perform a specific function Each organ system has a specific job Ex: Digestive system is made of several organs including the stomach and intestines

Structure of Animals Cells -basic unit of an animal’s structure -become specialized _______________________________ Tissues -made of cells that work together to perform a specific function __________________________________________ Organs -made of different types of tissues that work together to perform a specific function ____________________________________________________ Organ Systems -made of organs that work together to perform a specific function _____________________________________________________________ Organisms