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Cells
The place where life begins
What is a cell?
• A cell is the smallest
functional and
structural unit of all
living organisms
– This means that cells
make up all living things!
• An organism is any
living thing
– All organisms are made
up of cells
Itty bitty cells
• Most cells are too small
to see with your eyes
alone
• Why are they so small?
– Cells are limited by their
surface area
– Cells take in nutrients and
get rid of waste through
their surface
– If it’s volume grows too
big, there will not be
enough surface area to
pass nutrients and waste
through
Cell Theory
• All organisms are made
up of one or more cells
• The cell is the basic unit
of all organisms
• All cells come from
existing cells
Three important people to cell theory
Anton van
Leeuwenhoek
• Saw cells from
pond water under
a microscope
• Contributed to the
first part of cell
theory
Theodor Schwann
Rudolf Virchow
• Determined
animals were
made of cells after
Matthias Schleiden
determined plants
were made of cells
• Concluded all
organisms are
made of cells
• Concluded that the
cell is the basic
unit of life
• Proposed that cells
could only form
from the division
of other cells
• Responsible for
the 3rd part of cell
theory
Important Vocab
• Unicellular organism- 1 cell carries out all
functions of life
• Multicellular organism – cells have specialized
functions and work together for the good of
the organism
What do all cells have in common?
• Cell membrane- a
protective layer that
convers the cells surface
– Acts as a barrier
– Controls movement of
materials in and out of
the cell
• Cytoplasm- the area
inside of the cell
– Fluid
– Contains the organelles
Continued
• Organelle- small “bodies”
in the cell used to
preform specific functions
• DNA – provides the codes
for the instruction of all
cell processes
– Usually found in a
membrane bound
organelle called the
nucleus
2 Types of Cells
Prokaryotic
• NO nucleus or membrane
bound organelle
• DNA is located in the
cytoplasm
• Contain ribosomes
• Some contain flagella
– Hair-like structures for
movement
• Smaller than Eukaryotes
• Bacteria and Archaea
Eukaryotic
• Contain a nucleus and other
membrane bound
organelles as well as
ribosomes
• Not all the same
• Make up animals, plants,
protists, and fungi
• All multicellular organisms
have eukaryotes
• Can be unicellular