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Day 13We've been learning about organisms in different domains and kingdoms.

Are all of those organisms living?

Yes. The definition of an organism is "a living thing that can survive on its own." All organisms are living.

Living Things

DomainArchaea

DomainBacteria

DomainEukarya

Single vs. Multicellular

Contrasting Case Activity 3Investigation 3 – Microscopic Life

Organisms and Living Things

All organisms are living things.

Are all living things organisms?

What do these two images have in common?How are they different?Are they both living?

Microscopic Images

• Inside every cell, a number of important functions must occur.

• The cell must allow nutrients and gases in and out, and it must eliminate waste.

• Cells reproduce by splitting into new cells.

Life of a Cell

Where else have we seen these processes occur?

• The cell is called the basic unit of life because it is the smallest unit capable of carrying out the functions of life.

• Some cells are part of a multicellular organism.• This kind of cell has two jobs: to carry out all the functions needed to keep itself alive, and to work with surrounding cells to help keep the organism alive.

The Basic Unit of Life

• Can all cells survive on their own? • Could the cells pictured here survive without the rest of the organism?

Cells Working Together

Compare Single Cells

What do these two cells have in common? How are they different?

Compare Single Cells• Like a cheek cell, a paramecium is a single cell that carries out all the functions of life.

• Unlike a cheek cell, a paramecium can survive independent of the cells around it.

• This special quality makes a paramecium an organism as well as a cell.

Does living independently mean a paramecium does not need anything from its environment?

Discussion1.A 19th-century biologist studying cells

described them as leading a “double life.” What did he mean by this?

2.What clues might you look for to determine whether a cell is a single-celled organism or part of a multicellular organism?