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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)