The Replication Of DNA In Escherichia Coli

Understanding DNA can take a lot of studying and confusion to even get the general idea of the concept. The structure of DNA is very complicated and complex to understand, but researchers James Watson, Francis Crick, Maurice Wilkins, and Rosalind Franklin all developed the idea of the DNA structure in 1953. Deoxyribonucleic Acid is found in the nucleus of the cell. It is a double stranded molecule that contains the genetic code and is the main component of chromosomes. DNA is the blueprint of organisms. Nucleotides are the basic unit of DNA and they are made up of sugar, phosphate, and one of the four basis including adenine,

Translation is a task that makes ribosomes synthesize proteins utilizing mRNA transcript made during transcription. In the begining of this task mRNA attaches it self to a ribosome so that it can be reveal a codon (three nucleotides).

This paper explores the history and some interesting facts about DNA. The last couple centuries have seen an exponential growth in our knowledge of DNA. The history of the DNA can be traced back to multiple devoted scientist. This article attempts to summarize, and review the basic history of DNA while providing some fascinating information about it.

In the early 1950s, the race to find the structure of DNA was in full swing. The search was being conducted at three different colleges. At the California Institute of Technology, Linus Pauling,

Chemotaxis (chemical signal) and phototaxis (light stimulus) stimulate the flagellation to rotate counterclockwise (run) or clockwise (tumble).

Escherichia coli K12 is a well-studied gram-negative bacteria. First isolated from the human gut, is one of the most used in molecular studies, being the knowledge obtained from studies of E. coli possible to apply to other organisms (Burton and Kaguni, 1997). Some enzymes have a crucial role in the transcription control, the topoisomerases enzymes play an important role in the level of DNA supercoiling, an important property of DNA and chromatin (Gilbert and Allan, 2014). The supercoiling level is modified by a reaction that consists in the transient breakage of the DNA phosphodiester bonds and the movement of strands across the transient breaks (Tse-Dinh and Wang, 1986). In prokaryotes, these enzymes can be classified into two major groups, according to the mechanism of action. While the topoisomerase II (DNA gyrase) generates negative supercoils into relaxed DNA and relax positively supercoiled DNA, the topoisomerase I relax negatively supercoiled DNA. It is important to equilibrate the superhelical state of the cellular DNA (Hirose and Matsumoto, 2000).

The objective of this experiment is to conclude that the results of Griffin and Avery et al, can be duplicated in a way that will allow us to corroborate their results. The null hypothesis that this repeated experiment revolved around was that the DNA involved from the E. Coli would not undergo transformation and therefore grow a strain, which means that there would be growth on any of the plated specimens. This leads to the alternative hypothesis that only the plates that involved the DNase would not have growth as it has the heritable genetic information that would allow the transformation to occur and

The five most prominent biologists in Section 2 include Sister Miriam Michael Stimson, Lynn Margulis, Barbara McClintock, Hans Spemann, Francis P. Rous. First of all, Sister Miriam Stimson studied DNA with the use of infrared light. In order to be able to see only the A’s, C’s G’s and T’s of the DNA with the light, she created “pills” of potassium bromide which “were invisible to infrared.” Because of her experiments with the potassium bromide discs and infrared light she agreed with Watson and Crick’s theory: “DNA bases had only one natural shape, the one that produced perfect hydrogen bonds.” This discovery gave biologists an idea about the construction of DNA.

The work of these four people led to a complete restructuring of the beliefs of the scientific community regarding genetic information. Their initial word led to further work which encompassed their hypothesis of how DNA replicates itself. From this work came the modern technologies of DNA fingerprinting and sequencing.

DNA replication is described as semi-conservative. It is semi-conservative because the replication of one helix results in two daughter helices each of which contains one of the original parental helical strands. Furthermore, it is semi-conservative because the two new daughter DNA molecules are “half old” and “half new”; this means that half the original DNA molecule is saved, or conserved in the daughter DNA molecules.

DNA is like the blueprint for the creation and proper functioning of every living organism. Organisms can sometimes be divided into prokaryotes and eukaryotes. Examples of prokaryotes and eukaryotes include bacteria and humans, respectively. These organisms must possess a method of replicating DNA, so a copy is provided for each cell that divides. Each cell’s responsibility is coordinated by the piece of DNA and thus, makes it a very valuable part of the cell and organism. So what are the methods of replicating DNA in eukaryotes and prokaryotes? DNA replication in prokaryotes consists of several enzymes and proteins which are responsible for different tasks, but together make the process seem effortless. DNA replication in eukaryotes is similar, but more complicated given that eukaryotic chromosomes are linear, possess more than one origin, and have nucleosome structures which need to be replicated. Regardless, a technique named PCR, developed by Kary Mullis, has the ability to “produce exponentially large amounts of a specific piece of DNA from trace amounts of template DNA” (Bio-Rad). PCR has the ability to replicate DNA in eukaryotic cells. Prokaryotic replication and PCR both replicate DNA, so the similarities are apparent in terms of methods, but there also appears to be subtle differences concerning the enzymes and proteins utilized during each process.

1. The process where a cell passed its DNA sequence onto another cell is known as DNA replication. This process usually took place in the S phase cell cycle through mitosis where the copy of DNA molecule are segregated and cytoplasm open up leading to cell division. In order for the process to happen, an enzyme helicase must hack the hydrogen bond where the DNA “unzip” and “unwind” to establish two open template. DNA polymerase then replace the RNA primer by adding new complementary nucleotides to the templates by following the base pairing rules--A=T, C=G, G=C, and T=A. Once the process is complete, two new sisters DNA strand are produce identical to the original strand.

In 1962, the Nobel Prize was awarded to Francis Crick and James Watson for formulating the structure of the complex molecule known as DNA. These discoveries were a direct result of the accumulation of many scientists’ earlier analyses and findings of the DNA. Before Watson and Crick had developed the double-helical structure of DNA, indication of this genetic material had been revealed around the 1850’s. During the century following the first evidence of DNA, subsequent researchers had been eagerly examining the physical and chemical components of this molecule. Moreover, scientists such as Erwin Chargaff and Linus Pauling established a scientific foundation of research for future experts like Watson and Crick to analyze and interpret. The history of science acknowledges Watson and Crick’s findings as an exclusive discovery of their studies. However, the knowledge required to expose these innovative ideas are a culmination of “human events in which personalities and cultural traditions play major roles” (Watson and Stent, 3). Watson’s personal account within The Double Helix introduces the significance of these scientific influences on his research and discovery of the DNA molecular structure. Without major scientific figures, such as Max Perutz, Rosalind Franklin, and Linus Pauling, the conceptualization of Watson and Crick’s DNA structure would not have successfully developed as it did in the 1950’s.

The process of DNA replication plays a crucial role in providing genetic continuity from one generation to the next. Knowledge of the structure of DNA began with the discovery of nucleic acids in 1869. In 1952, an accurate model of the DNA molecule was presented, thanks to the work of Rosalind Franklin, James Watson, and Francis Crick. To reproduce, a cell must copy and transmit its genetic information (DNA) to all of its progeny. To do so, DNA replicates following the process of semi-conservative replication. Two strands of DNA are obtained from one, having produced two daughter molecules that are identical to one another and to the parent molecule. This essay reviews the three stages

Due to the DNA’s specificity, samples can be utilised for identification. DNA is a nucleic acid composed of deoxyribose sugar bound to a phosphate group and one of four nitrogenous bases (adenine, guanine, cytosine and thymine). Each section of these three components are referred to as nucleotides, which are joined to the phosphate or sugar of another nucleotide by strong covalent bonds to form a backbone. The nitrogenous bases are joined to complimentary bases of another nucleotide (adenine with thymine, guanine with cytosine) to create a double stranded molecule (Figure 2). To complete the double helical structure, the molecule coils to compact it’s contents. DNA molecules can contain up to two million base pairs, with a human genome containing approximately 3 million base pairs. The random assortment of nitrogenous bases as well as the numerous mutations within certain DNA sequences, results in genetically diverese DNA molecules and genomes between individials.