Structure and
Function of The Cell
Reference:
Modern Biology
CHAPTER 4
Multicellular Organization
Modern Biology
Chapter 4 - Sect. 3
Pgs. 86-88
BIG IDEAS
**The cells of multicellular organisms are specialized
to perform one or a few functions
**Cells of multicellular organisms depend on each
other for the survival of the organism.
MULTICELLULAR ORGANIZATION
Multicellular Organisms
• Contain many cells
– Each cell has specific job
• its structure fits its function or job
• As multicellular organisms develop,
their cells differentiate (change & separate)
to form different types of cells.
• The cells eventually group together to
form tissues
• Tissues come together to form organs
• Organs form organ systems and organ
system form the organism.
Cells tissues  organs  organ systems
ORGANISM
4 Levels of Organization
1. Cell
-performs functions that work with other cells to keep
organism alive
-many different types of cells
2. Tissue
-group of similar cells that carry out a common function
– Ex: epithelial tissue made of sheets of closely packed cells that
form surface coverings.
3. Organ
-group of several types of tissues that interact to
perform a function
- Ex: Your heart is made up of muscle tissue, nerve tissue, and
connective tissue. Muscle tissue makes your heart pump, nerve
tissue tells it when to pump and connective tissue holds the
parts together.
4. Organ System
-group of several organs working together
to perform a series of related tasks
Example: mouth, esophagus,
stomach, intestines work
together to digest food.
*All organ systems work together
to carry out all the functions
of life for the organism.
MULTICELLULAR ORGANIZATION
FYI: Plants also have cells, tissues, and organs.
Plant cells form different kinds of tissues. For
example, one tissue type covers the outside of a
leaf. Another tissue transports water and
nutrients.
Special kinds of tissue
form plant organs.
Flowers, leaves, stems,
and roots are all plant
organs.
MULTICELLULAR ORGANIZATION
COLONIAL ORGANISMS
Group of genetically identical cells
that live in a closely connected
group.
Example: Volvox
– Contains 500-6000 cells.
– Cells maintain individual existence.
» Some are specialized to carry out a
specific task.
Volvox Video
Volvox Dances - Bing Videos
STEM CELLS
• Undifferentiated (“blank
slate”) cells with the potential
to become any cell in the body.
– Found in embryos, umbilical
cords, and adult bone marrow
– Injected into patients to possibly
treat degenerative diseases,
burns, or other serious injuries
– Controversial because obtaining
embryonic stem cells requires
the destruction of living embryos
STEM CELLS
http://ed.ted.com/lessons/what-are-stem-cells-craig-a-kohn#watch
Microscopic (10X) view of a colony of
undifferentiated human embryonic stem cells