1. Specialized Cells

2. Specialized: Does one thing really well Cells look different because they have different jobs.

3. Stem cells… not specialized yet! Stem cells are cells that have not chosen a “job” yet Once a cell has chosen a job, it can’t change anymore You have the most stem cells before you are born Adults still have some stem cells that work to fix damaged tissues and make more stem cells

4. Stem cells in research Stem cell research is exciting to scientists because they might be able to use stem cells to fix medical problems Controversial research because sometimes the stem cells come from fetuses (not always). This is called embryonic stem cell research. The principal source of human embryonic stem cells is donated embryos from fertility clinics

5. Fat Cells Part of connective tissue. Primary purpose is to store energy for later—if there is not enough food, body uses stored fat

6. Bone Cells Provide support for bone structure. Marrow makes blood cells Some stem cells in bone marrow!

7. Blood Cells Red blood cells carry oxygen to tissues. White blood cells fight diseases. Platelets (cell fragments) clog up “leaks” and clot to form scabs

8. Nerve cells Carry electrical and chemical signals around the body. Neurons: nerve cells in the brain

9. Muscle Cell Muscle cells are attached to bones and make movement possible Long and thin Can stretch and contract like a rubber band

10. Skin Cells Protective barrier for waterproofing, block microorganisms and chemicals. Replicate quickly Screen harmful UV rays. Thermostat

11. Leaf Cells Regulates exchange of H20, O2 and CO2. Most of light absorption occurs here in photosynthesis. Takes a lot of energy to maintain

12. Root Cells Absorb water from ground Underground means no chloroplasts for photosynthesis

13. Plant trunk and stem cells Create tubes to carry water up to the leaves and food down to the roots Strong cell walls— keeps plant standing up.