1. Cell Specialization

2. Unicellular Organism – consists of only one cell
- that one cell carries out all functions required to maintain the life of the organism
Multicellular Organism – consists of more than one cell
Cells are specialized to perform certain functions (cell specialization/differentiation)

3. Examples of Cell Specialization
Neuron (nerve cell)
- sends info from one part of the body to another
- very long and thin

4. Examples of Cell Specialization
Red Blood Cells
- carry oxygen throughout body
- flattened disks so that they can easily flow through blood vessels

5. Examples of Cell Specialization
Sperm Cell
- fertilizes egg
- strong tail for quick swimming, distinct head for entering egg cell

6. Cell differentiation is a result of different gene expression.

7. Most cells in your body have the same DNA
Cells use only the DNA that they need; the rest is inactive
For example, skin cells use the DNA that codes for melanin (a skin pigment that protects from UV light)
Heart cells do not need melanin, so it is “turned off” in heart cells

8. Stem Cell Research
stem cells – cells of humans that can develop into different cell types

9. 2 kinds: embryonic and adult
some researchers believe that they can be a source of replacement cells to treat disorders (ex. Parkinson’s disease and burn injuries)
Embryonic stem cells
Adult stem cells

10. Protozoa
Protists are unicellular eukaryotes found in moist environments.
Protists have many characteristics that differentiate them for specific functions.
Eyespot
Contractile Vacuole
Locomotion
Pseudopods
Flagella
Cilia

11. Protozoa
Eyespots are localized region of pigment that determines the quality and quantity of light. (Phototaxis)
Some Protists can detect changes in chemicals in their environment and respond accordingly (chemotaxis)
Contractile vacuole regulates the water balance within the cell

12. Cell Communication Local Signaling:
Cells communicate with one another by secreting and receiving chemicals
- Chemicals released by one cell can influence the activity of another cell

13. Example of Cell Communication
- Sensory cells to nerve cells to muscle cells

14. Cell Communication (cont.)
Long Distance Signaling:
Hormone – communication chemicals that travel through the blood (ex. insulin, estrogen)
- Secreted by endocrine glands

15. Acts much slower than nerve impulses but effects last much longer
Only influence the action of target cells that have specific receptors