The cell theory states that all living things are made of cells, cells are the smallest unit of life, and existing cells come from other cells. Evidence for the cell theory includes observations of organisms under microscopes appearing to be made of cells, Hooke and van Leeuwenhoek's early microscopic observations of cells, cells carrying out functions but components not surviving independently, and all cells undergoing cell division. Unicellular organisms carry out all the functions of life such as metabolism, sensitivity, homeostasis, growth, reproduction, nutrition, and movement within a single cell.

1. 2.1Cell Theory
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2. Plant and animal cells
The cell
2.1: Cell Theory
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Nucleus
Plasma
Membrane
CytoplasmMitochondria
Vacuole
containing
sap
Vacuole
Membrane
Cell wall
Chloroplast
Generalised animal cell Generalised plant cell

3. 2.1.1:
Outline the cell theory.
Three basic Principles
All living things are made of cells.
Cells are the smallest unit of life.
Existing cells have come from other cells.
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2.1: Cell Theory

4. 2.1.2:
Discuss the evidence for the cell theory.
If you observe
organisms under a
microscope they
consistently appear
to be made of cells
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2.1: Cell Theory
All living things are made of cells.
http://botit.botany.wisc.edu/Resources/Botany/Cells%20and%20Tissues/Pinus%20Phloem/Sieves%20xs.jpg.html

5. 2.1.2:
Discuss the evidence for the cell theory.
Robert Hooke
(1635-1703)
Came up with the term
“cells” after viewing cork
under a microscope.
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2.1: Cell Theory
All living things are made of cells.
http://www.protopage.com/cellzmann#Untitled/Discovery

6. 2.1.2:
Discuss the evidence for the cell theory.
Antoni van Leeuwenhoek
(1632 – 1723)
Regarded as the “father of
microbiology”
Discovered “animalcules” in
water with his microscope
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2.1: Cell Theory
All living things are made of cells.
http://oldschoolscience.wordpress.com/category/leeuwenhoek/

7. 2.1.2:
Discuss the evidence for the cell theory.
While organelles carry out
metabolic function
The cell components can
not survive independently
outside of the cell
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2.1: Cell Theory
Cells are the smallest unit of life.
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/CellularRespiration.html

8. 2.1.2:
Discuss the evidence for the cell theory.
All cells carry out cell
division
Mitosis and meiosis in
eukaryotic cells
Binary Fission in
prokaryotic cells
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2.1: Cell Theory
Existing cells have come from other cells.
http://www.glogster.com/reavisbradley/glog-5628/g-6n8hoa2d0jt9i4i6hetuqg8?old_view=True

9. 2.1.2:
Discuss the evidence for the cell theory.
Louis Pasteur proved
in 1864 that life could
not occur by
spontaneous
generation (e.g. that
rats could form from
sweaty grain)
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2.1: Cell Theory
Existing cells have come from other cells.
Remak a Jewish
scientist discovered
“cell division” when
studying chicken
embryos

10. 2.1.3
State that unicellular organisms carry out
all the functions of life.
metabolism: chemical reactions inside the cell,
including cell respiration to release energy
sensitivity: perceiving and responding to
changes in the environment
homeostasis: keeping conditions inside the
organisms within tolerable limits
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2.1: Cell Theory
Functions of life

11. 2.1.3
State that unicellular organisms carry out
all the functions of life.
growth: an irreversible increase in size
reproduction: producing offspring either
sexually or asexually
nutrition: obtaining food, to provide energy
and the materials needed for growth
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2.1: Cell Theory
Functions of life

12. 2.1.3
State that unicellular organisms carry out
all the functions of life.
movement: via changes in size or appendages
such as flagella, following stimulus or changes
in turgor or full locomotion
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2.1: Cell Theory
Functions of life