1. Single Cell vs. Multi Cell Living Environment Mr. Shrout

3. Single Celled Organisms Single celled organisms were the first living things on earth. It is though that the first cells originated approximately 3.5 billion years ago (BYA) – Photosynthesis began around 3 BYA

4. Single Celled Organisms These organisms perform all life funtions within a single cell. They rely on a cell membrane for protection and organelles for processes such as digestion and protein synthesis Single, or unicellular organisms dominate life on earth in terms of numbers.

5. Single Celled Organisms Common Single Celled Organisms include : – all bacteria – Protozoa : Amoeba, Paramecia, Euglena, Stentor. – Simple algae : Volvox, Micrasterias, Spirogyra

7. Multicelled Organisms Most scientists agree that multicellular organisms originated approximately 1-2 billion years ago – By 500 Million years ago- plants and fungi had colonized land Mutlicellular organisms likely started off as colonies of single celled organisms that began working together – Similar in form and function to stromatolites

8. Characteristics of Multicellular Organisms Multicellular organisms rely on communication between specialized cells – Their cells develop in different ways to perform specific tasks – This process is called “cell specialization”

9. Multicellular Organisms Common Multicelled Organisms : – Complex animals. – Plants. – Fungi The organs of multicelled organisms often equate to cell organelles

10. Single or Multi? Volvox

11. Simple multicellular life

13. Similarities Both single and multicelled organisms: 1.Have the same chemical make up. 2.Use DNA to store genetic information. 3.Made of cells. 4.Perform metabolism. 5.Reproduce. 6.Maintain homeostasis. 7.Make their own energy.

14. Differences Multicelled organisms: 1.Have tissues, organs, and organ systems 2.Are more complex in structure 3.Are much larger in size 4.Have more genetic material