Stem Cell Research By Sydney Strunk

Images of Stem Cells

Functions Stem cells are capable of dividing and renewing themselves for long periods of time. These cells are unspecialized, meaning they do not have any specific tissues that perform a certain task. Stem cells are undifferentiated. This means that each cell can go on to develop into any type of cell that the body holds.

Functions (continued…) There are two basic types of stem cells: embryonic and adult. Embryonic stem cells eventually give rise to every cell type in the adult body. Adult stem cells help regenerate old or worn out tissues, such as the lining of the small intestine, the bone marrow, and the epidermis of the skin.

Structure Adult stem cells are found in umbilical cord blood, as well as in bone marrow, organs, and tissues. Adult stem cells occur after embryonic development.

Structure (continued…) Embryonic stem cells are located in the inner cell mass of the blastocyst. They stay in the blastocyst stage for 4 to 5 days after fertilization.

Osmosis Stem cells must take in energy, water, and other materials and must eliminate wastes. Materials enter and leave through the cell membrane. During osmosis, water molecules diffuse through the selectively permeable membrane of a stem cell until they are evenly distributed on both sides.

Osmosis (continued…) Particles continue to move across the membrane in both directions even when equilibrium is reached. Since about the same amount of particles are moving in each direction, the balance of particles inside and outside of the cell does not change.

Diffusion Diffusion does not require the stem cell to use energy because it depends on random particle movements. When diffusion occurs, molecules (except for water) move from an area of higher concentration to an area of lower concentration. Like osmosis, diffusion goes until equilibrium is reached.

Cellular Respiration Stem cells obtain energy from cellular respiration. There are two stages of cellular respiration: Glycolysis and oxidative respiration. Glycolysis breaks down glucose into smaller molecules. Since glycolysis does not use oxygen, fermentation is used instead.

Cellular Respiration (continued…) Stage 2, oxidative respiration, requires oxygen and is much more effective than glycolysis because it recovers energy from organic molecules. A stem cell’s energy comes mostly from oxidative respiration.