3.1 Cell Theory

KEY CONCEPT Cells are the Basic unit of life.

LEVELS OF ORGANIZATION

Nonliving Levels:

1.ATOM (element)

2.MOLECULE (compounds like

carbohydrates & proteins)

3.ORGANELLES (nucleus, ER, Golgi …)

LEVELS OF ORGANIZATION

Living Levels:

4. CELL (makes up ALL organisms- life begins)

5. TISSUE (cells working together

6. ORGAN (heart, brain, stomach …)

7. ORGAN SYSTEMS (respiratory, circulatory)

8. ORGANISM

4

LEVELS OF ORGANIZATION

Living Levels continued:

9.POPULATION (one species in an area)

10.COMMUNITY (several populations in an area

11.ECOSYSTEM (forest, prairie …)

12. BIOME (Tundra, Tropical Rain forest…)

13. BIOSPHERE (all living and nonliving things on Earth) copyright cmassengale

3.1 Cell Theory

The cell theory grew out of the work of many

scientists and improvements in the microscope.

• More was learned about cells

as microscopes improved.

• The cell theory is a unifying

concept of biology.

3.1 Cell Theory

Early studies led to the development of the cell theory.

• The Cell theory has three principles.

–All organisms are made of cells.

–All existing cells are produced by other living cells.

– The cell is the most basic unit of life.

3.1 Cell Theory

All cells share certain characteristics.

–Cells tend to be microscopic.

–All cells are enclosed

by a membrane.

–All cells are filled with

cytoplasm.

Bacterium

(colored SEM; magnification 8800x)

cell membrane

cytoplasm

Prokaryotes include bacteria & lack a nucleus or membrane-bound structures called organelles

Eukaryotes include most other cells & have a nucleus and membrane-bound organelles (plants, fungi, & animals)

Cells May be Prokaryotic or Eukaryotic

Prokaryotes

Nucleoid region contains the DNA

•Cell membrane & cell wall

• Contain ribosomes (no membrane) to make proteins in their cytoplasm

Eukaryotic Cell

Contain 3 basic cell structures:

• Nucleus

• Cell Membrane

• Cytoplasm with organelles

Two Main Types of Eukaryotic Cells

Plant Cell Animal Cell

Organelles

Very small size

Can only be observed under a microscope

Have specific functions

Found throughout cytoplasm

3.1 Cell Theory

3.1 Cell Theory

3.1 Cell Theory

Which Cell Type is Larger?

_________ > _____________ > ___________ Plant cell Animal cell bacteria

Word Roots Knowing word roots can improve your

vocabulary! centro- = the center; -soma = a body (centrosome: material present in the cytoplasm of all eukaryotic cells and important during cell division)

chloro- = green (chloroplast: the site of photosynthesis in plants and eukaryotic algae)

cili- = hair (cilium: a short hair-like cellular appendage with a microtubule core)

cyto- = cell (cytoplasm: a semifluid medium in a cell in which are located organelles)