DNA is organized into genes and stores genetic information. DNA molecules are long, slender molecules that carry the heritable information of organisms on to future generations. Because of their size, it is impossible to see a single DNA molecule with the naked eye. It would take about 300,000 DNA molecules side by side to make a bundle as thick as a human hair. When subjected to certain conditions, it is possible to collect “large” amounts of DNA to make it visible. As part of the chromosomes, the information contained in genes can be transmitted faithfully by parents through gametes to their offspring.
For the gene’s DNA to subsequently influence an inherited trait, the stored genetic information in the DNA in most cases is first transferred to a closely related nuclei acid, RNA or ribonucleic acid. In eukaryotic organisms, RNA most ofther carries the genetic information out of the nucleus, where chromosomes reside into the cytoplasm of the cell. In the cytoplasm, the information in RNA is translated into proteins, which serve as the end products of most all genes. The process of transferring information from DNA to RNA is called transcription.
The subsequent conversion of the genetic information contained in RNA into a protein is called translation. DNA molecule exists in cells as a long coiled structure often described as a double helix. Each strand of the helix consists of a linear polymer made up of genetic building blocks called nucleotides. There are four types of nucleotides which vary depending on the four nitrogenous bases of the molecule. The four nitrogenous are A(adenine), G(guanine), T(thymine) and C(cytosine). These comprise the genetic alphabet which in various combinations, will specify the components of proteins.
It was established in 1953 by James Watson and Francis Crick that the two strands of their proposed double helis are exact complements of one another, such that the rings of the ladder always consists of either A=T, or G=C base pairs. This complementarity between adenine and cytosine nitrogenuos base pairs and between guanine and cytosine nitrogenuos base pase pairs, attracted to one another by hydrogen bonds, is critical to genetic function. Complementarity serves as the basis for both the replication of DNA and for the transcription of DNA into RNA.
OBJECTIVES * To learn basic DNA extraction processes. * To properly and successfully extract DNA from banana using cell disruption and separation techniques. * To investigate the effect of temperature on DNA extraction from bananas. * To observe the extraction of genomic DNA from plant cells. * To understand how a buffer solutions disrupts the plasma membrane and releasing cellular components into the solution. MATERIALS AND APPARATUS PER CLASS * (60-70 oC) Water bath * 95% Ethanol * Extraction solution * Cheesecloth Ice chest containing ice PER GROUP * 40g Banana * 2 ziplock bags (Label ‘Extraction 1’ and ‘Extraction 2’) * 2 funnels * 2 test tubes * 50ml conical tube (2 pieces) * 500ml beaker (2 pieces) * Glass Rod (2 pieces) * Shampoo 4ml * Distilled water 40ml * Table Salt (NaOH) 0. 3g PROCEDURE (A) Extraction solution recipe: 4ml of shampoo was mixed with 36ml of distilled water. The solution was stirred well and slowly. The mixture was divided into two 50ml conical flasks (20ml each). The conical flasks was labelled S and SS. 0. g of salt was added into flask SS. The salt was dissolved by stirring slowly to avoid foaming. (B) Banana Extraction 1. A water bath was prepared. (60 oC) 2. 20g of banana was added into each ziplock bag labeled ‘Extraction 1’ and ‘Extraction 2’ 3. Extraction solution ‘S’ was added into ziplock ‘Extraction 1’ and extraxtion solution ‘SS’ into ziplock bad ‘Extraction 2’. The bag was closed with minimum content of air. 4. The bananas were mushed carefully to avoid the bag from breaking. The bananas were mashed for about 5 minutes. 5.
The banana mixtures were cooled in the ice chest containing ice for 2 minutes. Then the bananas were mushed more. The banana mixtures were cooled, the mushed again. This process was repeated for 4 times. 6. The mixtures were filtered through cheesecloths. 7. Approximately 3ml of banana solution were dispenced into each test tube. 8. The test tubes were carefully handled to avoid shaking. Approximately 2ml of cold 95% ethanol was added into each test tube. 9. The test tubes were then observed. Result Photo 1: Test tubes containing solution S and SS CONCLUSION
We manage to learn basic DNA extraction processes. We are able to properly and successfully extract DNA from banana using cell disruption and separation techniques. We succesfully investigated the effect of temperature on DNA extraction from bananas. We are able to observe the extraction of genomic DNA from plant cells. We understood how a buffer solutions disrupts the plasma membrane and releasing cellular components into the solution. REFERENCES: BOOKS: * Neil A. Campbell, Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V.
Minorsky, Robert B. Jackson, Biology (8th Ed), Pearson International Edition: Pearson, Benjamin Cummings. * Peter J. Bowler (1989). The Mendelian Revolution: The Emergence of Hereditarian Concepts in Modern Science and Society. Johns Hopkins University Press. * Pragya Khanna. Essentials of Genetics. I. K International Publising House. * Elof Carlson (The Unfit), Mendel’s Legacy: The Origin of Classical Genetics, Cold Spring Harbour Laboratory Press, USA * Benjamin Cummings(2005), iGenetics: A Mendelian Approach, Pearson; University of Chicago, USA