If it disappears it's likely because enzymes are still present that are breaking apart the DNA in your sample. Using more sophisticated chemicals in a lab, it is possible to obtain a sample of DNA that is very pure. DNA purified in this way is actually quite stable and will remain intact for months or years. Cells with more chromosomes contain relatively more DNA, but the difference will not likely be noticeable to the eye. For example, plant seeds yield a lot of DNA because they have very little water in the cell cytoplasm.
That is, they have a small volume. So the DNA is relatively concentrated. You don't have to use very many seeds to get a lot of DNA! Peas are a good source of DNA because they are a seed. But, we also chose the pea for historical reasons. Gregor Mendel, the father of genetics, did his first experiments with the pea plant.
How does the experiment compare when using animal cells instead of plant cells? The DNA molecule is structurally the same in all living things, including plants and animals. That being said, the product obtained from this extraction protocol may look slightly different depending on whether it was extracted from a plant or an animal. For example, you may have more contaminants proteins, carbohydrates causing the DNA to appear less string-like, or the amount of DNA that precipitates may vary.
Good sources for animal cells include chicken liver, calf thymus, meats and eggs from chicken or fish. We at the GSLC have done a fair amount of testing with the split pea protocol and the wheat germ protocol. We have found no difference in the "product" nucleic acids that is observable, whether using meat tenderizer or not. So, the step was left out of the wheat germ protocol, but kept in the split pea protocol just for fun.
Even though it's not necessary, it may be doing something we can't see. For example, perhaps by using the meat tenderizer you get a purer sample of DNA, with less protein contaminating the sample. Yes, in theory. The same basic materials are required, but the protocol would need to be scaled down using smaller volumes of water, soap and alcohol. That means that you will not extract an amount of DNA large enough to visualize with the naked eye. If you wanted to see it, you would need a centrifuge to spin down to the bottom of the tube the small amount of DNA present in the sample.
This sample could be used for gel electrophoresis, for example, but all you will see is a smear. Unless you cut the DNA with restriction enzymes, it is too long and stringy to move through the pores of the gel.
A scientist with a lab purified sample of genomic DNA might also try to sequence it or use it to perform a PCR reaction.
But, your sample is likely not pure enough for these experiments to really work. How is DNA extraction useful to scientists? When do they use such a protocol, and why is it important?
The extraction of DNA from a cell is often a first step for scientists who need to obtain and study a gene. The total cell DNA is used as a pattern to make copies called clones of a particular gene. These copies can then be separated away from the total cell DNA, and used to study the function of that individual gene. Once the gene has been studied, genomic DNA taken from a person might be used to diagnose him or her with a genetic disease.
Alternatively, genomic DNA might be used to mass produce a gene or protein important for treating a disease. This last application requires techniques that are referred to as recombinant DNA technology or genetic engineering. Unfortunately, a microscope will not allow you to see the double helical structure of the DNA molecule.
You'll only see a massive mess of many, many DNA molecules clumped together. In fact, the width of the DNA double helix is approximately one billionth of a meter! This is much too small to see, even with the most powerful microscope. Instead, a technique called X-ray crystallography can be used to produce a picture of the DNA molecule. Step 1: Blender Insanity! Add shampoo until solution volume is ml.
Stir slowly to avoid foaming of the shampoo. Measure 20 ml of solution into 1L zipper bags 1 per student pair. Close bag and squeeze out air. Place the bags into the hot water bath for about minutes, making sure the fruit solution is fully beneath the water line. Occasionally shake the bag to evenly distribute the heat.
Repeat this procedure 5 times. Tape the cheese cloth over the beakers. Filter the fruit mixture through the cheese cloth. Combine solutions from all student groups at this point. Let the solution drain 5 minutes. Do not agitate the solution. Let the solution sit for two minutes without disturbing it. Each cell has an entire copy of the same set of instructions, and this set is called the genome. They can use DNA to make new medicines or genetically modify crops to be resistant to insects.
They can solve who is a suspect of a crime, and can even use ancient DNA to reconstruct evolutionary histories! To get the DNA from a cell, scientists typically rely on one of many DNA extraction kits available from biotechnology companies. During a DNA extraction, a detergent will cause the cell to pop open, or lyse, so that the DNA is released into solution. Then alcohol added to the solution causes the DNA to precipitate out.
In this activity, strawberries will be used because each strawberry cell has eight copies of the genome, giving them a lot of DNA per cell. Most organisms only have one genome copy per cell. Download 0 items. Twitter Pinterest Facebook Instagram. Email Us. See our newsletters here. Would you like to take a short survey? This survey will open in a new tab and you can fill it out after your visit to the site. Yes No.
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