Friday, August 3, 2012

Simple DNA Isolation

Baca artikel berikut dalam bahasa Inggris [Read article below in English] 

Talking about DNA, mostly of us imagine something so abstract and very small. Especially about the isolation of DNA, often thought its a very complicated process with very sophisticated tools. Whereas DNA isolation is not always so, there is some simple DNA isolation technique that effective enough for isolating DNA, not only simple in procedure, even the materials used are easily obtained from the surrounding environment. The technique is suitable for introduction of the DNA with lab activity MTs / SMP (junior high school) also MA / SMA (senior high school) students.

DNA (Deoxyribose Nucleic Acid) is a master molecule (main molecule) that encodes all the information needed for metabolic processes in any organism (Jamilah, 2005).
DNA is composed of three main components of the sugar deoxyribose, nitrogenous bases and phosphate, the three of them combining to form nucleotides (Istanti, 1999). DNA molecules are bound to form a chromosome, and is found in the nucleus, mitochondria and chloroplasts. DNA is composed of nucleotides of the double helix, where the nitrogenous bases and the two "strand" polynucleotide pairs with each other through hydrogen bonds and fixed between a single nucleotide with another nucleotide associated with the phosphate bond. DNA contained in every living cell and is referred as the "blueprint of life" because this molecule plays an important role as a carrier of hereditary information that determines the structure of proteins and other metabolic processes (Jamilah, 2005).

DNA can be denatured and renaturated. Moreover DNA can be isolated. Zubaidah (2004) in Jamilah (2005) states that DNA isolation can be done through: preparation of cell extracts, purification of DNA from cell extracts and DNA precipitation. Actually, DNA isolation can be done in various ways, but in any kind or parts of plants may give different results, it is because of compounds called polyphenols and polysaccharides in high concentrations can inhibit DNA purification. When the DNA isolation performed using a sample of fruit, the different water content of each fruit, can give different results. Fruits with high water content will have different isolates when compared to the fruit with low water content.

DNA isolation process begins with the DNA extraction process. Extraction is important to separate the DNA with other unwanted particles. This process must be done carefully, so its not causing too much damage to DNA. To remove the DNA from the cell, can be done by breaking the cell wall, plasma membrane and nuclear membrane, its can be done either by mechanical or chemical ways. Mechanical ways can be done with a blending or mechanical muller using mortar and pistil. While the chemical can be by administering substances that can damage cell membranes and the nuclear membrane, such as the detergent.

The addition of detergents in the isolation of DNA is done because detergents can cause damage to cells membrane, through the bonds formed on the hydrophobic detergent with protein and lipid to form a compound membrane "lipid-protein-detergent complex'. These compounds can be formed by the proteins and lipids, because they have hydrophilic and hydrophobic ends, as well as detergents, which can form a chemical bond (Machmud, 2006).

Tools and Materials
1.      Beaker glass
2.      Fruit knive
3.      Mixer
4.      Filter
5.      Blender Machine
6.      Spatula
7.      Test tube dan tube rack

1.      Various types of fruit
2.      detergent
3.      Aquades
4.      Salt
5.      96% cold ethanol


  1. Dissolving detergent, liquid soap and soap cream into 56 mL of aquades, stirred gently for 15 minutes.
  2. 100 grams of fruit plus 100 mL of aquades put into the machine blender, then blend for 1 minute. 
  3. 4 mL of each solution of soap mixed with 4 mL of each fruit juice 
  4. Adding salt to a spatula and then stirred for 10 minutes until a homogeneous mixture is obtained. 
  5. Filter the resulting mixture at twice the previous point 
  6. 6 mL filtered at the point he was put into a test tube and add 9 ml of cold 96% ethanol 
  7. Observe the onset of DNA, including the time required, the color, as well as the extent of DNA that is formed

Baca artikel di atas dalam bahasa Inggris [Read article in English] 

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