What is DNA? Importance of DNA

Posted by bhavin | Posted in , | Posted on 10:30 PM

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Deoxyribonucleic Acid (DNA) is present in the chromosomes of all the humans. DNA is

the vital biological material which helps to enable an individual’s identity. DNA plays a vital role in solving crime and also determines paternity. DNA is a type of nucleic acid which is made up of thousands and thousands of nucleotides and certain amino acids. The long strand of DNA can be built by the nucleotide.

Half of the DNA is received from our parents and the other half of it comes maternally. DNA can be extracted form number of sources like our hair, blood, saliva, razor clipping etc. DNA is tested in the laboratory by which we can understand our genetic relationships. The DNA contains the blueprints of life and it also helps in exercising control over the functions performed by the cells and helps to indicate the ancestry.

DNA is found in all the living organisms even in some of the viruses. It is found in the nucleus of the chromosomes. The repair and growth of the body can take place easily as DNA is present in every single cell of our body.

Importance of DNA

DNA is biologically essential for life. DNA is found in all the living organisms in every cell and it contains the storage of complex information about our nature, behavior etc. DNA helps to determine the factual circumstances so it is a very unique component of our body. For legal procedures also we can identify the matches between the DNA samples and understand link between the individuals. Most of the police and investigations agencies rely upon the DNA tests as a fact finding technique. DNA is one of the accurate techniques for positive identification of the living organisms.

DNA Microarrays

Posted by bhavin | Posted in | Posted on 10:29 PM

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A DNA microarray is a small stamp sized piece either of plastic or of glass on which the single strands of DNA fragments are attached in a microscopic array. It represents the genes of an organism. The word “array” usually refers to placing something in a systematic and an organized arrangement. All the cells in a human body are comprised of an identical genetic material. However, the same genes are not active in every cell. The study of which genes are active and which are inactive in the different cells helps the scientists in understanding the functioning of the cells and its impact, when the other genes do not function properly. But now with the advancements in science and technology, it is possible for the scientists to examine how active all the different genes are at any given time and the boost in the development of DNA microarray technology has made it possible.

The DNA microarrays are made by the robotic machines. These machines arrange minuscule amounts of thousands of gene sequences on a single microscopic slide. This cellular machine starts copying some segments of that gene, as soon as the gene is activated. The resulting product is referred to as mRNA that is nothing but a template of the body responsible for creating proteins. The mRNA, thus generated by the cell is complimentary that will be bound to the original part of the DNA strand from which it was being copied.

The DNA microarray technology is very useful. It helps the researchers to know more about different diseases like mental illness, heart disease, infectious disease, etc. It is also used widely in the study of cancer. Scientists are able to classify the different types of cancer based on the organs where the development of tumors takes place. With the help of this technology, they will be further able to classify the types of cancers based on the gene activity type in the tumor cells of the body. The researchers are, thus able to invent effective treatment strategies that will be targeted to a particular cancer type directly. They are able to develop more efficient treatments to treat cancer.

Some of the useful applications of the DNA microarrays are: Disease screening- the genes that are associated with the life threatening disease like cancer or heart disease can be tested regularly to check whether the person is at an increased risk of developing it. This gradually helps in early diagnosis and treatment.

Comparative genome hybridization- this is a practice that interprets the genomic losses and gains or any alteration in the number of copies of a specific gene concerned in a diseased state.

Mutation analysis- this is a procedure that points out the differences in a single Nucleotide polymorphism and a particular nucleotide polymorphism associated with a particular disease.

The DNA microarray has made many promises for the progressive advancements in the future. It helps the scientific community to procure the readouts of all the different components of the body. No doubt, this will, some day lead to molecular diagnostics, personalized drugs and integration of treatment as well as diagnosis.

DNA Sequencing

Posted by bhavin | Posted in | Posted on 10:28 PM

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DNA Sequencing is the process that determines the exact order of the three billion chemical building blocks known as bases and abbreviated as A, T, C and G. These three billion building blocks are responsible to make up the DNA of the twenty-four different human chromosomes. DNA Sequencing maps are greatly used by the scientists for exploring the human biology as well as many other complex phenomenons related to our body.

The exact order of the bases A, T, C and G are determined in a piece of DNA through DNA Sequencing. In the core, DNA is used as a template for generating a set of fragments differing in length from each other by a single base. These fragments are then separated by size and the bases are recognized at the end, recreating the original sequence of DNA.

The most frequently used method for DNA Sequencing is the dideoxy method or the chain termination method. This method was developed by Fred Sanger. The basics involved in this method is the use of adapted bases known as dideoxy bases. When the DNA piece is replicated and the dideoxy base is integrated in a new chain, the replication reaction stops immediately.

Most of the DNA Sequencing is done by this chain termination method. In this method, a new DNA strand is synthesized on a single stranded template and the chain terminating nucleotide analogues are randomly incorporated. This method leads to the production of a set of DNA molecules that differs in length by a nucleotide. The last base in every molecule can be identified easily due to its unique label. Separation of the DNA molecules as per to their sizes, locates them in a correct order to read off the sequence.

The DNA Sequencing method forms the basis of the automated cycle sequencing reactions. In these reactions, fluorescent dyes are added and a laser, inside the automated DNA Sequencing machine is used for analyzing the DNA fragments that are produced in the process. For sequencing a piece of DNA, you require a short DNA “primer” that is complimentary to the DNA that you wish to sequence, a template DNA i.e. the DNA that you want to sequence, an enzyme known as DNA polymerase and four nucleotides.

DNA Sequencing is a very useful method. The most foreseen application of DNA Sequencing is seen in accurate sequencing of the genomes and genes in your body. Only up to 500-800 bases can be sequenced in one demonstration. So, obviously, the larger DNA molecules along with the genomes should be broken down in small fragments before sequencing them. You will get accuracy only when you sequence each template for a number of times. Low fidelity single pass sequencing is very useful for quick accumulation of the sequence data. Another application where DNA Sequencing is seen is in resequencing the same DNA molecule again and again. This is very important, for instance, in typing of the single nucleotide polymorphisms.

DNA Sequencing is the center of Human Genome Project and it promises to revolutionalize the Biomedical Sciences as well as the treatment of the human disease.

mRNA Labeling

Posted by bhavin | Posted in , | Posted on 10:27 PM

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mRNA refers to messenger RNA. The gene expression studies based on the microarrays enable the simultaneous investigation of the relative amount of messenger RNA for a number of genes with the help of the fluorescently labeled nucleic acid targets. The most of the universal methods makes use of the enzymatic techniques like oligo-dT primed reverse transcription for producing the DNA. These labeling methods have found to have some shortcomings such as laborious protocols, sequence bias, introduced labeling, inability to perceive small alterations in the expression levels and very high experiment-to-experiment variability.

In such cases, a novel and an innovative method of labeling is used. This method makes use of the platinum linked cyanine dyes to chemically and directly label the mRNA from a very little amount of the total RNA. The directly labeled mRNA yields unbiased and highly accurate data of the differential gene expression. The gene expression data that is perceived by using the mRNA labeling method is highly precise without any errors at all. There is no labeling bias and we see a dynamic range over a number of orders of magnitude. This method boasts the highest accuracy levels in identifying the differentially expressed genes. It also cuts down the requirement to run several replicate assays. Thus, minute changes in the expression of genes is now possible to get detected on a large-scale gene expression profile assays with the help of such an easier, quicker as well as simpler procedure.

Nevertheless, the use of the random primers may outwit some of these issues along with the enzymatic labeling techniques, but still we can say that the mRNA Labeling system is quite beneficial. It is an innovative labeling technique that makes use of chemical reagent to label the mRNA directly with the fluorescent dyes. This mRNA is labeled in the entire RNA mixture in a single step non-enzymatic reaction; thereby reducing the errors that have been occurred in the previous methods because of multiple steps. The mRNA thus formed, is free from any labeling bias and it produces reproducible expression profile of the gene and also enables a great amount of accuracy in identifying the differentially expressed genes.

mRNA Labeling System- there are some reagents to be used to prepare the first strand of the DNA for microarray Synthesis. These reagents are highly efficient and full length. Random primers and Oligo dT are used for DNA synthesis. Adequate reagents are provided for ten labeling reactions and they are supplied with the control templates for the Quality Check purpose. This mRNA Labeling system provides the reagents for reverse transcription and for labeling the cDNA from the mRNA templates. The labeled cDNA is, thus used for northern blot applications, FISH or as probes for the microarrays. This mRNA labeling system is stored at a temperature of about 20 degrees C and it remains stable for atleast 6 months.

The labeling of the mRNA is usually done with the help of the MICROMAX ASAP RNA Labeling Kit. The kit has detailed manufacturer’s instructions regarding how the procedure should be carried out to avoid any errors in the process.

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