Homologous recombination (HR) can be explained as a process where DNA is exchanged or copied between two chromosomes or different regions of the same chromosome. The process requires homology between the exchanging DNA regions. Homologous recombination repairs DNA breaks, especially double stranded breaks (DSBs), stabilizes and repairs stalled forks. HR consists of a series of inter related pathways that function in repair of DNA breaks (Figure 4). 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).
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 .
Although, personality is unique to the individual, experts in the field of psychology have studied the idea that personality is somewhat based upon biology, therefore implying that the biological makeup plays a role in a person’s personality. Extensive research and indisputable evidence through long-term studies has supported the idea that personality is directly influenced by genetics. Evidence that supports the biological influence on personality development is based on direct evidence through the examination of genes and studies of individuals who have the same genetic makeup. Both identical and fraternal twins are good candidates and are commonly used for genetic studies in medical and psychology research. Throughout history, many twins have been placed in situations where they were raised in completely different environments, therefore they have been utilized in testing to determine the influence of genetics on every aspect of our composition.
DNA in forensic science The majority of cells making up the human body are diploid cells carrying identical DNA, with the exception of haploid gametes and red blood cells. Several types of biological evidence such as blood and hair are commonly used in forensic science, which is the scientific study of evidence for crime scene investigations and other legal matters. Forensic science is used for the purpose of DNA analysis, this is the analysis of DNA samples to determine if it came from a particular individual. DNA analysis is done by obtaining DNA samples from an individual; next, a large sample of DNA is produced from amplified selected sequences from the DNA collected. Finally, the amplified DNA regions are compare using a gel.
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.
The first part of our lab started with a presentation, it consisted of 24 pages, each page covered a basic knowledge of blood evidence analysis. The presentation was labeled, “Basics of Blood Evidence Analysis”, a copy will be available in my casefile. In an order of what was presented, I first learned the different significances of blood evidence. Spatter patterns help recreate what happened at the scene, and D.N.A. also helps to identify and exclude suspects.
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.
HeLa cells have allowed scientists to study cells in a more detailed way and gather information about cells impossible before HeLa. One contribution made by studying HeLa was the knowledge of how many chromosomes normal human cells have. This knowledge has allowed scientists to better understand and treat diseases and disorders that deal with irregular numbers of chromosomes. Many findings that help scientists better understand cells have been made with the help of HeLa. Key Idea 2: Medical Field Many of the findings
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.