The Cell Theory-Guided Notes
What is a Theory?
–When scientists agree upon an ______________________or idea, after repeated
experimentation, they call it a theory.
What is a cell?
A cell is the _______________ unit of structure and function in living things.
Robert Hook 1665

English Scientist who was one of the first people to observe cells.

Built his own ____________________ __________________________.

Observed cork which seemed to be made up of empty little boxes, which he
named cells.
Anton van Leeuwenhoek 1674
In the mid 1600s, a Dutch fabric merchant, made a simple microscope with a tiny glass
_______________ for a lens.
Observed a different drops of water and found 0ne-celled organisms
Formulation of the Cell Theory
3 German Scientists are credited.
1. Matthias ___________________- 1830’s studied plant parts and concluded plants
are made of cells.
2. Theodor ____________________- After observing animal cells concluded all
animals made of cells.
3. Rudolf Virchow- hypothesized that cells divide to form new cells and proposed
a cell came from a cell that already existed.
The Cell Theory
1. All organisms are made up of one or ____________ cells.
2. Cell is the basic unit of structure and function.
3. All cells come from _________________ cells.
1. All organisms are made up of one or more cells
Cells are divided into two groups
1. _____________________cells
2. _____________________cells
2. Cell is the basic unit of structure and function.
 Cells are building blocks of living organisms
 Cells have the same basic parts to do specific tasks,
• Take in __________________
•
•
•
•
Store
Reproduce
Breakdown __________________
Take in and use _______________
3. Cells come from pre-existing cells.

Two methods of reproduction
1. Meiosis
2. Mitosis
Organisms are divided into two groups.
1. Prokaryotes are single-celled organisms, and are divided into two groups.
2. Eukaryotes are multi-celled organisms.
 Organisms are classified into three domains.
Name of Domain
Group
Bacteria
Prokaryotes
Achaea
Prokaryotes
Eucaryota
Eukaryotes
1. Prokaryotic cells
–Found only in _________________ organisms such
as Paramecium-found in freshwater ponds and
bacteria.
–Does not have membrane bound structures inside the
cell.
–No nucleus
2. Eukaryotic Cells
–Cells
with membrane-bound structures inside the
cell.
–Found in ______________________ organisms.
–Cells contain a nucleus
Multi-celled organisms include:
 plants
 animals
 molds
 fungi
Organization of cell in Multi-celled Organism
1. _____________________ The smallest unit that has properties of life.
2. ______________________ Group of similar cells that work together
to do one job. Ex: Heart tissue
3. _______________________ Two or more types of tissue that work
together. Ex: Heart : nerve, blood, and cardiac muscle tissue.
4. ________________________ A group of organs working together to
perform a certain function.
Ex: Cardiovascular system includes heart, arteries, veins, and
capillaries.
5.________________________- Many organ systems that work together
Ex: Humans
Different cells perform different functions in multi-celled organisms.
Plants
•
Leaves - epidermis cells- protect the plant.
• Trunks of trees- xylem cells- extra thick cell walls.
Humans
• Nerve cells – carry messages to and from different parts of the body
• Blood cells carry ______________ to and from different parts of the body.
 Cells Are Different for a reason, it depends on their ________________
 Size and Shape are different for a reason.
Nerve Cells – are long to cover a large area
Muscles cells- thin and long, in order to expand and contract
Blood cells are flexible so they can flow through our veins and organs.
Plant cell are rigid so they can support the plants
Ultimately Cells……
• Take in nutrients and convert it to energy
• Sized and shaped differently according to their job- (function).
• Perform different jobs depending on the needs of the cell
• Work together to maintain the life of an organism.
The Cell Theory
1. All organisms are made up of ____________ or more cells.
2. Cell is the basic unit of __________________ and function.
3. All cells come from _______________________ cells.