1. Chapter 5 Cell Growth and Division Mr. Shilala DAHS
5.5 Multicellular Life
Chapter 5 Cell Growth and Division
Mr. Shilala
DAHS

2. KEY CONCEPT Cells work together to carry out complex functions.

3. Multicellular organisms depend on interactions among different cell types.
Tissues are groups of cells that perform a similar function.
Organs are groups of tissues that perform a specific or related function.
Organ systems are groups of organs that carry out similar functions.
vascular
tissue
leaf
stem
lateral
roots
primary
root
SYSTEMS
root system
shoot system
CELL
TISSUE
ORGAN

4. Organ systems help an organism maintain homeostasis
Example Plants need to maintain a specific water level or they can wilt and die
Absorb water through roots and expel through Stomata in leaves

5. What label should replace the X in the diagram above?

6. Specialized cells perform specific functions.
Cells develop into their mature forms through the process of cell differentiation.
Most cells contain a full set of DNA.
However, a cell differentiates among the genes and only uses certain ones
Example - Making a specific meal
DNA = a cookbook
Different genes = different ingredients
Different cells = different recipes
Outer: skin cells
Middle: bone cells
Inner: intestines

7. A cell’s location in an embryo helps determine how it will differentiate.
Example animal cell
Many rapid divisions after fertilization
Cells migrate to specific region
Begin to differentiate
Resemble hollow ball
Outer: skin cells
Middle: bone cells
Inner: intestines

8. Stem cells have the ability to
Stem cells are unique body cells. They can come from adults and embryo’s
Stem cells have the ability to
Divide and renew themselves
Remain undifferentiated in form
Develop into a variety of specialized cell types
When stem cells divide they form 2 stem cells or 1 stem cell and 1 specialized cell

9. Stem Cell Classification
Stem cells are classified into three types.
When stem cells divide they form 2 stem cells or 1 stem cell and 1 specialized cell
Totipotent, or growing into any other cell type
Pluripotent, or growing into any cell type but a totipotent cell
Multipotent, or growing into cells of a closely related cell family

10. Adult stem cells (Somatic stem cell)
First, an egg is fertilized by a sperm cell in a petri dish. The egg divides, forming an inner cell mass. These cells are then removed and grown with nutrients. Scientists try to control how the cells specialize by adding or removing certain molecules.
Come from, brain, liver, muscle, dental and even fat cells.
Can even come from children and umbilical cord blood.

11. Advantages and Disadvantages of Adult stem cells
Grown in lab.
Can be put directly into the body with very little chance of rejection
Less ethical issues
May be pluripotent rather than multipotent
Few in number, difficult to isolate and tricky to grow in the lab
May contain more DNA abnormalities

12. Embryonic stem cells Come from donated embryo’s grown in a clinic
Result of In-vitro fertilization
Taken from undifferentiated cells 3 – 5 days old
Called Inner cell mass
Don’t have any specific cell characteristics
Embryonic stem cells are pluripotent and can be grown indefinitely in culture.
Can become any of the 200 types of cells

13. Advantages and Disadvantages of Embryonic stem cells
Body may reject the cells
Could grow unchecked and become a tumor
Kills the embryo
Creates ethical issues
Pluripotent
Can be grown indefinitely in culture.
Can become any of the 200 types of cells

14. Currently realized and potential benefits of Stem Cells.
Used to treat leukemia and lymphoma
May cure disease – diabetes
Replace damaged organs - heart
May revolutionize the drug development process.
Downside – time and money
Little chance to reach patient

15. Stem Cell Wrap up
Do you think stem cell research should be legal or illegal. Answer the question at the bottom of your notes!