Composing DNA Essay should be ideally done in two stages. First and foremost is the pre writing stage, where one needs to think and collect ideas for the essay. It becomes a lot easier when one proceeds with a pre drafted outline, especially in case of long assignments. This stage involves careful thinking and deliberation on the topic one is going to write on. One should begin with questions like, what facts or ideas should be used?
Next comes choosing the theme point that one is going to present, if one cant chose, sticking to any one theme is advised. Read more on the following topics: AIDS essay writing, tourism essay papers and college essay prompts.
Once done with choosing the theme, one must find the best ways to tell the reader about it. DNA Essay requires careful picking of facts that optimally support your ideas and zeroing in on a basic structure one needs to work on. Second comes the writing stage where the chief concern is to transform your ideas into well composed sentences. This calls for precision in terms of language, grammar and comprehension skills. One should start with an introduction to essay, with some background information and develop supporting paragraphs following the correct paragraph format.
One can also consult a good dictionary to help finding additional words to express definite meanings. Meselson and Stahl conducted their experiment with common bacteria of human intestine i. They used heavy isotope of nitrogen for labelling DNA. The bacteria were grown on culture medium containing heavy isotope of Nitrogen [N15] for 14 generations 30 minutes per generation to replace the normal nitrogen [N14] of E. Then the bacteria were transferred to normal nitrogen medium.
The density of DNA was determined after one, two and three generations. It is possible to detect minute differences in density through density gradient centrifugation.
District bands are formed in centrifuge tube for different density DNA. He used heavy isotope of hydrogen [H3] for labelling of DNA. It replaces thymine of DNA with tritiated thymidine. The chromosome of E. Slides were coated with photographic emulsion or film and stored in dark place. The tritiated thymidine emits particle in dark due to its radioactive decay. These particles expose the film.
These films are then developed and interpreted. If the exposure is light on the autoradiograph, it suggests labelling of one strand of DNA, which indicates semi- conservative replication. Cairns observed light film exposure in the chromosome slides of E. He treated root tips of Viciafaba with radioactive thymidine to label the DNA. Then root tips were grown in normal medium. The treated root tips will produce hybrid cells containing normal and labelled chromosomes in subsequent generation cell division when grown on normal medium.
The DNA replication is associated with chromosome replication. In prokaryotes bacteria and viruses , the DNA is circular. Several models of replication of circular DNA have been suggested. This model of DNA replication in prokaryotes was proposed by Cairns in According to this model the DNA replication consists of following important steps. The double stranded circular DNA starts unwinding or separation at a specific point called origin.
Two growing points are established. As the growing points move apart, unwinding of the DNA double strand takes place. This unwinding creates torque since the parental DNA strands cannot unwind freely. At the point of origin, bidirectional replication is initiated. Both strands of DNA are replicated. This leads to further unwinding of DNA double strand, resulting in formation of torque. The torque leads to super twisting of DNA strand. As a result of super twisting, one of the strand is cut nicked which makes the parental strand to rotate freely.
The cut is made by a swiveling protein, which relieves the strain. The breaks are sealed by swiveling protein and thus the replication is over. The replication process continues in this way. Cairns type replication has been demonstrated in the bacteria E. This model of circular DNA replication was proposed in This model is most widely accepted.
First the chromosome becomes double stranded by synthesis of a negative strand. The original strand is positive. The negative strand is synthesized in side of parental positive strand. The negative or inner strand remains a close circle and the positive strand is nicked at a specific site by endonuclease enzyme. This enzyme recognizes a particular sequence at this point.
The original positive strand comes out in the form of a tail of a single linear strand as a consequence of rolling circle. In the nucleus it is a major component of chromosome, whereas in cytoplasm it is found in mitochondria and chloroplasts. In prokaryotes, it is found in the cytoplasm. Mostly the DNA structure is double stranded in both eukaryotes and prokaryotes. However, in some viruses DNA is single stranded. DNA is a double stranded molecule held together by weak bonds between base pairs of nucleotides.
The four nucleotides in DNA contain the bases: The DNA is capable of self-replication. This is the only chemical which has self-replicating capacity. The DNA replicates in semi-conservative manner. The DNA may be linear or circular. It may be double stranded or single stranded.
It may be right handed or left handed. The DNA may be repetitive or unique. It may be nuclear or cytoplasmic. DNA plays important role in various ways.
It is used in transcription i. It carries genetic information from one generation to the next generation. DNA stores and transmits the genetic information in cells. It forms the basis for genetic code. The genes are made of DNA and are responsible for passing on traits from generation to generation. DNA contains the genetic instructions for the development and functioning of living organisms.
Thus it is the substance of heredity. This brilliant research work resulted in significant breakthrough in understanding the gene function. This structure has been verified in many different ways and is universally accepted.
James Watson and Francis Crick were awarded Nobel prize in for this significant contribution in the field of molecular biology.
Free DNA papers, essays, and research papers. Bacteria strains and DNA extraction - Materials and method Bacteria strains and DNA extraction A collection of standard bacterial strains containing E. amylovora strains and several species of bacteria confirmed by Biochemical, Carbohydrates and Virulence tests for identification of E. amylovora .
ADVERTISEMENTS: In this article we will discuss about: 1. Meaning of DNA 2. Features of DNA 3. Molecular Structure 4. Components 5. Forms. Contents: Essay on the Meaning of DNA Essay on the Features of DNA Essay on the Molecular Structure of DNA Essay on the Components of DNA Essay on the Forms of DNA [ ].
Essay on DNA: The Doble Helix - INTRODUCTION The essential component of life can be acknowledged and is made up of a nucleic acid known as DNA. DNA is the abbreviated form for the word deoxyribonucleic acid and it is the “carrier of genetic information” (McMurry, Ballantine, Hoeger, & Peterson, , pg. ). DNA contains . Essay about dna - Instead of worrying about essay writing find the needed assistance here Leave your essays to the most talented writers. % non-plagiarism guarantee of custom essays & papers.
Science essays, thesis & dissertations, like an essay on DNA, require a prudent knowledge or at least a little brief idea about the topic. Other than class texts, some good information could be gathered from internet, encyclopedias, magazines . DNA DNA is the genetic martial (gene) for hereditary in humans and almost all other organisms.2 It is stored in a cell’s nucleus (nuclear DNA) and mitochondria (mitochondrial DNA.) It is composed of four nucleic acids which combine together to form a double helix strand of DNA.