1. The Organization of Living Things
Hierarchy of Organisms

2. 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

3. 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

4. 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

5. 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

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

7. 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

8. 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

9. 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

10. Nerve
Muscle
Connective
Epithelial

11. 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

12. 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

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