Initially, stretches of single stranded DNA (ssDNA) are resected at the stalled forks or DSB ends which are quickly bound by replication protein A (RPA). Rad51 replaces RPA and binds to these ssDNA with the aid of the Rad52 mediator function (21,22). Rad51 form a nucleoprotein filament, which can then engage in homology search by strand invasion forming a homologous DNA
Abstract The transformation principle suggests that bacteria use DNA as their genetic material and are able to exchange their genetic material via a process of transformation. Griffith had theorised the concept of the transformation principle using two strains of bacteria and studied their ability to recombine. Avery and MacLeod followed his studies and suggested DNA was sensitive to DNase, and that the enzyme would destroy the bacteria's ability to exchange genetic material and transform into a new strain. This was then tested in the labs at Wits by second year students where they studied the transformation of ampicillin sensitive E. coli to ampicillin resistant E. coli. The results obtained there were similar to those of Avery and MacLeod,
DNA synthesis. When primers detect and limit the amplification DNA sequence on two sides, the thermostable DNA polymerase synthesizes a complementary fragment from the 3 'end of the primers from both DNA single chain fragments using the nucleotides added to the mixture. The procedure is carried out at 72 ° C, using a thermostable Taq polymerase. APPLICATIONS: The ability of the PCR to analyze a very small amount of DNA plays an important role in disease diagnostics. One of the important uses of PCR is the diagnosis of possible AIDS infection at a very early stage even before antibodies have developed .
It continued to be used throughout the 1990’s when Argentina became the first country to create a genetic database. This was specifically set up to identify missing children. Following this, in the early 2000’s crime investigation took a largely DNA-led approach. It was used successive of the attack on the World Trade Centre in New York. These two events significantly increased the use of DNA analysis in forensic science.
also helps to identify and exclude suspects. The white blood cells contain the D.N.A. used to identify those suspects. Also it was explained that blood when oxygenated is bright red, and when unoxygenated is dark and almost purple. Professor Martin presented that blood evidence can help sequence what has happened at a crime scene, whether the bloody fingerprint came first or the spatter did.
The technique is often used in research to detect specific proteins which have extracted from cells. In this process, a mixture of proteins separated based on two distinguishing properties which are molecular weight and antibody binding specificity. According to the procedure, proteins first separated based on size which have to perform with SDS-PAGE. Next, the proteins from the gel are then transferred to a polymer membrane (PVDF or nitrocellulose) to make them more accessible to the antibodies that specific to the target protein. Cytotoxic assay Cytotoxicity is described as the quality of being toxic to cells.
2.7 Polymerase Chain Reaction (PCR) In 1971, Dr. Har Gobind Khorana’s group described the idea to amplify a DNA (Templeton, 1992). Later on in 1985, Kary B. Mullis invented the Polymerase Chain Reaction (PCR) which is used today in different fields, such as scientific research, clinical diagnostics and criminal investigations. PCR is a molecular biology tool that is used to amplify a fragment of DNA to generate thousands to millions of copies. This technique is based on an enzymatic reaction which is controlled by thermal cycling, where every cycle consists of heating and cooling steps. The generated DNA fragments after every cycle are used as templates for the next cycle.
This is between the deoxyribose sugar of one nucleotide and the phosphate component of the other nucleotide, which brings about the alternating sugar phosphate backbone.All biological information is stored in DNA which makes every organism unique. There are pieces of DNA called genes which determine a particular trait in a living organism.The sugar phosphate backbone of the DNA resist against cleavage, and both double helical strands stores the biological information, which is transcribes / replicated as they separate. These DNA strands are anti-parallel to each other as they run from and are transcribed from a 3-5 end. They are similar but they run in opposite directions. The 5(prime) carbon would be located at the top of the leading strand which is replicated continuously and the carbon on the other end, where on the lagging strand the 3(prime) carbon is at the lower portion where these are replicated in sections known as Okazaki fragments.
At each PCR cycle it is possible to measure the amount of amplified product. The detection is performed using non-specific fluorescent dyes that intercalate with any double-stranded DNA or using sequence-specific DNA probes. After each cycle, to estimate the DNA concentration, the fluorescence is measured with a detector and is compared with a control used as reference. Given its capacity to detect the presence and abundance of a specific DNA sequence, RT-PCR techniques have been developed to quantify HPV-DNA in clinical samples (Molijn et al. 2005) and (Dutra et al.
A nucleus is basically the “brain” of a cell. It controls reproduction and contains the genetic information needed to reproduce. It can be found in eukaryotic cells. B. Endoplasmic reticulum- there are two types, the rough and smooth endoplasmic reticulum. The rough endoplasmic reticulum is involved in synthesizing and packaging proteins for use.