Definition
Example
Questions:
1. What are some functions of a cell?
a. ______________________________
b. ______________________________
c. ______________________________
Organism
2. List an example of a unicellular organism?
a. ______________________________
3. List four examples of multicellular organism?
a. ______________________________
b. ______________________________
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Definition
Example
c. ______________________________
d. ______________________________
4. Are humans multicellular or unicellular? (circle one)
5. What characteristic distinguishes a unicellular organism from a
multicellular organism?
Cell
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Definition
Example
Video (2.54 min) http://www.youtube.com/watch?v=gFuEo2ccTPA
Read: Introduction to Cells
Unicellular
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Definition
Example
Multicellular
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All living organisms (living thing) are composed of cells. The cell is
the basic unit of life where all life’s functions occur. Unicellular
organisms (single-celled organism) like bacteria are composed of just
one cell, whereas multicellular organisms (many-celled organism)
can be composed of trillions of cells. Humans are composed of 100
trillion cells (100,000,000,000,000). Examples of multicellular
organisms include protists, fungi, plants and animals. Most plant and
animal cells are microscopic and therefore can only be observed
under the microscope.
The one cell of a unicellular organism must be able to perform all
the functions necessary for life. These functions include metabolism,
homeostasis and reproduction. Specifically, these single cells must
transport materials, obtain and use energy, dispose of wastes, and
continuously respond to their environment. The cells of a
multicellular organism also perform these functions, but they may
do so in collaboration with other cells.
But a cell, even the single cell of a unicellular organism, must be
able to interact with its external environment. The cell must be able
to bring molecules in from the outside, and expel unwanted waste
products. Knowing the structure and functions of organelles (little
organs) of the cells like the ribosomes, nucleus, mitochondria and
chloroplasts are necessary to understand how a cell functions, and
ultimately you.