|OBSERVATION OF THE DNA
The DNA she is one of the fundamental parts of the chromosomes, are structures constituted by two small filaments or arms, that can be equal or unequal, are united by a common point called Centromere; they vary in form and size, they can turns easily at the time of the cellular division by means of a microscope.
The chromosomes chemically are formed by proteins and the Acid Desoxiribonucleico or DNA.
Structure of the DNA
The DNA it is formed by called units nucleotides, each one of as it has three substances: the phosphoric acid, a sugar of five carbons called pentose and one bases nitrogen.
The phosphoric acid forms the group phosphate; the nitrogen base is of four classes: adenine (a), guanine (g), cytokine (c) and timina (t).
According to the discoverers of the DNA, James Watson and Francis Crick, the DNA it is formed by one double chain of nucleotides that form a species of double similar helix to stairs in spiral; to the sides a phosphate and a sugar get ready in alternate form and in the steps two nitrogenadas bases.
Functions and Properties of the DNA
a) The DNA it controls the activity of the cell.
b) He is the one that takes the genetic information of the cell, since the DNA units, calls genes, are the people in charge of the structural characteristics and the transmission of these characteristics from a cell to another one in the cellular division.
The genes are located throughout the chromosome.
c) The DNA it has the property to duplicate itself during the cellular division to form two identical molecules, for which it needs that in the nucleus nucleotides, energy and enzymes exist.
The main objective of this experiment is the one of being able to only observe without help of no optical instrument (microscope) the DNA, using material caretakers whose cost is not high.
- Liver of chicken
- Liquid detergent
- Enzymes (strop of meat in dust or juice of papaya
- White alcohol
- Container of glass or plastic
- Beaker or any glass with graduations (for babies)
1. - We must cut in small pieces the chicken liver, soon we placed it in the mixer and we spill sufficient water as so that, after 10 seconds to liquefy, we have the consistency of a cream.
Soon we spill the liquefied one in a container that has graduations (beaker) by means of a strainer to separate some parts that have not liquefied the sufficient thing.
We measure the liquefied one in the container and add ¼ of liquid detergent of the total of the liquefied one.
We toss around smoothly with the help of a spoon.
2. - We add 1 Enzyme spoon (in this case we can use strop of meat or juice of papaya) and toss around slowly with well-taken care of and by about 5 minutes. If we mixed with too much rapidity or with much force the danger is run to break the DNA, and so we could not observe it.
3. - We spill the mixture in a high and thin container until half.
We tip the container and we spill alcohol by far care, avoiding that is mixed with the liquid of down.
After some minutes it will be possible to be observed some white filaments within the alcohol and that rise of the mixture of liver, detergent and enzymes. We are observing the DNA!
A mixer has been used to separate the cells some of others, in this help also the detergent.
The enzymes destroy to the cells and do possible that the DNA can be seen that contain.
Vargas Palomeque, Miguel; Gonzales Mendoza, Rossemary; I supplement Technical Scientist, published by the Newspaper, La Paz, Bolivia, 1993.
Bolivar S, Rubén Darío; Gomez R., Miguel A., Biología Integrada, Editorial Voluntad S.A., Bogota, Colombia, 1989.
|Purchase constructed and ready experiments to use