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  • Publicado : 6 de octubre de 2010
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Introduction
DNA is composed of DeoxyriboseNucleicAcid. It is found in the nucleus of cells and contains all the genetic information. This genetic information is found in the form of nucleic acids.These nucleic acids are long chain molecules, composed of smaller sub-units called Nucleotides. These Nucleotides are joint together by covalent bonds. This is a condensation reaction which producesH2O (Water). Nucleotides are molecules made up of 3 parts: Pentose sugar, Phosphate group and an organic base.

In DNA, there are four types of nitrogenous bases: Adenine, Thymine, Guanineand Cytosine. These bases pair with each other, in order to make DNA double stranded. However, these bases have a base pairing rule. Adenine, will only pair with Thymine, with a double hydrogen bond;Guanine, will only pair with Cytosine, with a triple hydrogen bond.

Additionally, as it can be seen in the diagram, DNA is a double stranded molecule and it is called DNA double helix, becauseof this. Also, the bonds between the bases are hydrogen bonds. They cause the DNA to twist. The two strands of DNA run in anti-parallel directions and they always run from 5’ to 3’. In order to studyDNA, it has to be flat, and the hydrogen bonds are broken to make it flat.
Finally, the sugar and the phosphate group found in the nucleotides, make up the backbone of DNA. They are joint bycovalent bonds and they are known as the sugar-phosphate backbone.

Method
To do this experiment we are going to use:
• Half a banana
• A zip close bag
• Pipettes
•DNA extracting fluid (15 ml)
• Filter funnel
• Filter paper
• Beaker
• Test tube
• Methylated spirits (5 ml)

The steps to follow are:1. To begin, we place half a banana in a zip close bag and we remove all the air before sealing it. This is done to prevent the bag from bursting.
2. Then we mash the banana in the...
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