1. Levels of
Organization

2. Cell Specialization
23 chromosomes
Zygote: fertilized cell created by the union of the egg and sperm
Zygote divides into Embryonic stem cells
Potential to become any type of cell
Average human:
100 trillion cells
Over 200 types of human cells
Egg Cell
23 chromosomes
Embryonic Stem cells
zygote

3. Stem cell controversy
Stem cells are being used in research to help treat various diseases… so why is this controversial?
If someone has brain damage… stem cells can be grown into new brain cells to help the person recover.

4. Stem cell controversy
Stem cells are being used in research to help treat various diseases… so why is this controversial?
If someone has muscle damage… stem cells can be grown into new muscle cells to help the person recover.

5. Stem cell controversy
Stem cells are being used in research to help treat various diseases… so why is this controversial?
If someone is blind… stem cells can be grown into new eye cells to help the person recover.

6. Stem cell controversy
Stem cells are being used in research to help treat various diseases… so why is this controversial?
Where do stem cells come from?
When couples seek help to create a child, many eggs and sperm are collected and mixed together to create many embryos
Embryos are implanted into the woman, where hopefully they will grow into a baby
Stem cells are obtained from left over 4-5 day embryos
Why controversial?
Reason: Embryo is destroyed in the process of obtaining the stem cells
Argument: Some claim this kills a human life
Counter Argument: These leftover embryos will soon be discarded as medical waste
The Myth:
When a woman gets an abortion, she can donate the dead embryo to stem cell research.

7. Determination Determination Few weeks into development
Genes program the stem cell to become a specific cell
Irreversible
Lump of stem cells

8. Differentiation Differentiation
Cells acquire the structures & functions of a specialized cell
Specific genes activated
Some stem cells become…

9. Differentiation Differentiation
Cells acquire the structures & functions of a specialized cell
Specific genes activated
Other stem cells become…

10. Differentiation Differentiation
Cells acquire the structures & functions of a specialized cell
Specific genes activated
And other stem cells become…

11. Quick Questions
Do your muscle cells have the same DNA as your skin cells?
Yes
Do your skin cells have the same DNA as your brain cells?
Do your brain cells have the same DNA as your liver cells?
So if all your cells have the same DNA, how do they know to do different jobs?
Stay tuned for the answer

12. Stem cell (soon to be muscle cell)
Gene A
Gene B
Gene C
Gene D
Gene E
Gene F
Gene G
If these cells have the same DNA, how will the top cell know to become a muscle cell?
These light switches are symbolic of the genes inside each stem cell.
Stem cell (soon to be nerve cell)
Gene A
Gene B
Gene C
Gene D
Gene E
Gene F
Gene G

13. Stem cell (soon to be muscle cell)
Gene A
Gene B
Gene C
Gene D
Gene E
Gene F
Gene G
The proteins created in the top cell will cause the stem cell to become a muscle cell….
The proteins created in the bottom cell will cause the stem cell to become a nerve cell.
During “differentiation”, certain genes are activated in some cells, but deactivated in others.
What do genes direct cells to create?
Stem cell (soon to be nerve cell) ON ON ON
Gene A
Gene B
Gene C
Gene D
Gene E
Gene F
Gene G

14. Differentiation Differentiation
Brain cells
Differentiation
Cells acquire the structures & functions of a specialized cell
Specific genes activated
Muscle
cells
Pancreas cells
Skin cells

16. Programmed cell death (apoptosis) between the fingers & toes

17. Incomplete Apoptosis (Webbed Toes)

18. Organization
Cell: Basic unit

19. Organization Muscle Tissue Contracting cells Skeletal, cardiac cells
Cell: Basic unit
Tissue: Group of cells
4 types

20. Organization Connective Tissue Support the body Bone, fat, tendons
Cell: Basic unit
Tissue: Group of cells
4 types

21. Organization Connective Tissue Support the body Bone, fat, tendons
Cell: Basic unit
Tissue: Group of cells
4 types
Ligaments connect your femur (thigh bone)…
to your tibia (shin bone)

22. Organization Connective Tissue Support the body Bone, fat, tendons
Cell: Basic unit
Tissue: Group of cells
4 types

23. Organization Epithelial Tissue protective sheet of cells
skin, stomach lining
Cell: Basic unit
Tissue: Group of cells
4 types

24. Organization Nerve Tissue Transmit electric signals
Brain & Spinal Cord
Cell: Basic unit
Tissue: Group of cells
4 types

25. Organization Cell: Basic unit Tissue: Group of cells 4 types
Organ: Groups of tissue
Ex: lung contains each tissue

26. Organization Cell: Basic unit Tissue: Group of cells 4 types
Organ: Groups of tissue
Ex: lung contains each tissue
Organ System: Group of organs working together
Respiratory System

27. Organization Cell: Basic unit Tissue: Group of cells 4 types
Organ: Groups of tissue
Ex: lung contains each tissue
Organ System: Group of organs working together
Respiratory System

28. Organization Cell: Basic unit Tissue: Group of cells 4 types
Organ: Groups of tissue
Ex: lung contains each tissue
Organ System: Group of organs working together
Respiratory System

29. Organization Cell: Basic unit Tissue: Group of cells 4 types
Organ: Groups of tissue
Ex: lung contains each tissue
Organ System: Group of organs working together
Respiratory System
Organism: all organ systems working together

30. YouTube Review: Levels of Organization

31. Review What is a zygote? What is the specific function of a stem cell?
How does “determination” differ from “differentiation”?
Cells are programmed to die during a process called ______.
From smallest to largest, name the 5 levels of organization.
Name the four types of tissues.
Which tissue is able to stretch and contract?
Which tissue transmits electric signals?
Which tissue covers and protects the body?
Which tissue connects the body?