- Slides: 13
Specialized Cells • Specialized: Does one thing really well • Cells look different because they have different jobs.
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
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
Fat Cells • Part of connective tissue. • Primary purpose is to store energy for later —if there is not enough food, body uses stored fat
Bone Cells • Provide support for bone structure. • Marrow makes blood cells • Some stem cells in bone marrow!
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
Nerve cells • Carry electrical and chemical signals around the body. • Neurons: nerve cells in the brain
Muscle Cell • Muscle cells are attached to bones and make movement possible • Long and thin • Can stretch and contract like a rubber band
Skin Cells • Protective barrier for waterproofing, block microorganisms and chemicals. • Replicate quickly • Screen harmful UV rays. • Thermostat
Leaf Cells • Regulates exchange of H 20, O 2 and CO 2. • Most of light absorption occurs here in photosynthesis. • Takes a lot of energy to maintain
Root Cells • Absorb water from ground • Underground means no chloroplasts for photosynthesis
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.