Make DNA visible. (Hands-On Activity).Stem cells stem cells, unspecialized human or animal cells that can produce mature specialized body cells and at the same time replicate themselves. Embryonic stem cells are derived from a blastocyst (the blastula typical of placental mammals; see embryo), which is very young contain all the genes (hereditary HEREDITARY. That which is inherited. information) needed to give rise to any of the body's 200 different tissue types, including skin, bone, and heart cells. Where are genes stored? Along a double-stranded molecule called DNA DNA: see nucleic acid. DNA or deoxyribonucleic acid One of two types of nucleic acid (the other is RNA); a complex organic compound found in all living cells and many viruses. It is the chemical substance of genes. , which can be found inside every cell's nucleus (center). Without DNA, stem cells would lack their incredible morphing Transforming one image into another; for example, a car into a tiger. The term comes from metamorphosis. Morphing programs work by marking prominent points, such as tips and corners, of the before and after images. powers. Normally, DNA is microscopic microscopic /mi·cro·scop·ic/ (mi?kro-skop´ik) 1. of extremely small size; visible only by the aid of the microscope. 2. pertaining or relating to a microscope or to microscopy. because it's encased en·case tr.v. en·cased, en·cas·ing, en·cas·es To enclose in or as if in a case. en·case  ment n. inside cell,
but with the right tools you can make it visible. In this experiment,
you will extract real DNA from the embryos of wheat-germ grains (wheat
germ wheat germn. The vitamin-rich embryo of the wheat kernel that is separated before milling for use as a cereal or food supplement. wheat germ Noun the vitamin-rich middle part of a grain of wheat comes from wheat seeds, which produce new wheat plants). Developed by Louisa A Stark. Adapted from the Genetic Science Learning Center Web site: gslc.genetics.utah.edu YOU NEED: 1 teaspoon (1 gram) raw wheat germ * 1/4 teaspoon (1 milliliter) liquid detergent * 1 tablespoon (14 ml) rubbing alcohol (70% isopropyl alcohol) * 1 tablespoon (20 ml) hot tap water (50 [degrees] to 60 [degrees] C) * 50 ml test tube (beaker or spice jar will also work) * graduated cylinder * glass or wooden stirring rod * paper clip hook * eyedropper * paper towels TO DO: 1. Place 1 teaspoon of raw wheat germ in a 50-ml test tube. 2. Add 20 ml of hot tap water and mix constantly for 3 minutes. 3. Add 1/4 teaspoon of detergent and mix gently every minute for 5 minutes. 4. Try not to create foam, but if you do use an eyedropper to remove it from the top of the solution. 5. Tilt the test tube at a slight angle and slowly pour 1 tablespoon of rubbing alcohol down the side so that it forms a separate layer on top of the solution. Be careful not to mix the two solutions together. DNA separates from the wheat germ at the water-alcohol boundary. If alcohol mixes with water, the wheat germ will become too diluted and the DNA will not precipitate, or separate from the solution. 6. Let the test tube sit for a few minutes. White, stringy DNA will began to appear at the water-alcohol boundary. After about 15 minutes, the DNA will float to the top of the alcohol layer. 7. Use a stirrer or paper clip hook to collect the DNA. 8. Allow the DNA to air dry on a paper towel. CONCLUSION: How do the ingredients in this experiment work? (For an explanation, ask your teacher. Teacher: Please see p. TE8.) |
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