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Proteins are responsible for forming body structures such as organs and tissue and the control of chemical reactions, and the transmission of signals between cells. When a cell’s DNA is mutated, an aberrant protein is created, disrupting the body’s regular activities and leading to diseases like cancer.
FREMONT, CA: The genome is an organism’s whole set of DNAs. The approximately 3 billion DNA base pairs or letters that contribute to the human genome are found in virtually every cell in the body. DNA is a four-letter language that includes all of the information needed to construct the human body. A gene is a piece of DNA that contains the instructions for producing a specific protein or group of proteins. Each of the 20,000 to 25,000 genes in the human genome codes for three proteins on average.
Genes, which are packed into the nucleus of a human cell on 23 pairs of chromosomes, direct the production of proteins with the help of enzymes and messenger molecules. An enzyme, in particular, copies information from a gene’s DNA into a molecule known as messenger ribonucleic acid (mRNA). The mRNA goes from the nucleus to the cytoplasm, where a ribosome reads it. This tiny molecular machine uses the information to link together small molecules called amino acids in the exact order to make a specific protein.
Proteins are responsible for forming body structures such as organs and tissue and the control of chemical reactions, and the transmission of signals between cells. When a cell’s DNA is mutated, an aberrant protein is created, disrupting the body’s regular activities and leading to diseases like cancer.
What is DNA sequencing?
The term ‘sequencing’ refers to finding the exact order of the nucleotides in a DNA strand. Researchers are not required to disclose both bases of a pair since bases exist in pairs, and the identification of one of the bases in the pair dictates the identity of the other member of the pair.
DNA polymerase (the enzyme in cells that synthesizes DNA) is employed to build a new strand of DNA from a strand of interest in the most common method of sequencing employed today, known as sequencing by synthesis. During the sequencing step, the enzyme inserts individual nucleotides that have been chemically labeled with a fluorescent label into the new DNA strand. As this occurs, a light source excites the nucleotide, causing a fluorescent signal to be released and measured. The signal varies depending on which of the four nucleotides was used. This approach can produce ‘reads’ of 125 nucleotides in a row, as well as billions of reads at a time.
Researchers must read the sequence of overlapping segments to build the sequence of all the bases in a big piece of DNA, such as a gene. This makes it possible to piece together the longer sequence from lesser sections, similar to piecing together a linear jigsaw puzzle. Each base must be read at least numerous times in the overlapping portions during this operation to ensure accuracy. DNA sequencing can be used to look for genetic variations and mutations that could play a role in the onset or progression of a disease.