Why is detergent necessary to extract dna

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! Step 2: Soapy Peas. Pour your thin pea-cell soup through a strainer into another container like a measuring cup. Add 2 tablespoons liquid detergent about 30ml and swirl to mix.

Let the mixture sit for minutes. Why am I adding detergent? Step 3: Enzyme Power. Step 4: Alcohol Separation. What is that Stringy Stuff?

Try these ideas or some of your own: Experiment with other DNA sources. Blending separated the pea cells. To see the DNA, we have to break open these two sacks. We do this with detergent. Why detergent? How does detergent work? Think about why you use soap to wash dishes or your hands. To remove grease and dirt, right? Soap molecules and grease molecules are made of two parts: Heads, which like water. Tails, which hate water. When detergent comes close to the cell, it captures the lipids and proteins.

After adding the detergent, what do you have in your pea soup? The DNA in the nucleus of the cell is molded, folded, and protected by proteins. The meat tenderizer cuts the proteins away from the DNA. I don't think I'm seeing DNA. What should I be looking for? What can I do to increase my yield of DNA? Understanding the Science behind the Protocol. Why add salt? What is its purpose?

Salty water helps the DNA precipitate solidify and appear when alcohol is added. Why is cold water better than warm water for extracting DNA? How is the cell wall of plant cells broken down? It is broken down by the motion and physical force of the blender. What enzyme is found in meat tenderizer?

Why does the DNA clump together? How can we confirm the white, stringy stuff is DNA? How long will my DNA last? Will it eventually degrade and disappear?

Does chromosome number noticeably affect the mass of DNA you'll see? Why are peas used in this experiment? Are they the best source of DNA? What sources might I use to extract DNA from animal cells?

Why do peas require meat tenderizer, but wheat germ does not? Can you extract human DNA using this protocol? What can be done with my extracted DNA?

APA format:. Genetic Science Learning Center. Once extracted, DNA can be used for molecular analyses including PCR, electrophoresis, sequencing, fingerprinting and cloning. Add to collection. Go to full glossary Add 0 items to collection. 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. Most organisms only have one genome copy per cell.

Observations and results Were you able to see DNA in the small jar when you added the cold rubbing alcohol? Was the DNA mostly in the layer with the alcohol and between the layers of alcohol and strawberry liquid?

When you added the salt and detergent mixture to the smashed strawberries, the detergent helped lyse pop open the strawberry cells, releasing the DNA into solution, whereas the salt helped create an environment where the different DNA strands could gather and clump, making it easier for you to see them.

When you added the salt and detergent mixture, you probably mostly just saw more bubbles form in the bag because of the detergent. After you added the cold rubbing alcohol to the filtered strawberry liquid, the alcohol should have precipitated the DNA out of the liquid while the rest of the liquid remained in solution.

A single strand of DNA is extremely tiny, too tiny to see with the naked eye, but because the DNA clumped in this activity you were able to see just how much of it three strawberries have when all of their octoploid cells are combined! This activity brought to you in partnership with Science Buddies. Already a subscriber? Sign in. Thanks for reading Scientific American.