It's skinny as a whip and smart as one too, containing all the information necessary to build a living organism. In a very real sense, DNA is information.
DNA is a very large molecule, made up of smaller units called nucleotides that are strung together in a row, making a DNA molecule thousands of times longer than it is wide. Each nucleotide has three parts: a sugar molecule, a phosphate molecule, and a structure called a nitrogenous base.
The nitrogenous base is the part of the nucleotide that carries genetic information, so the words "nucleotide" and "base" are often used interchangeably. DNA was largely ignored for decades after a German chemist, Friedrich Miescher, first isolated the white, slightly acidic substance from the nucleus of cells in Very few people thought that DNA could be the hereditary material.
No one could imagine how such a monotonously simple molecule could contain the information necessary to build a living organism. But during the s and s, new experiments began to suggest that DNA might, in fact, be important. It turned out that different strains of bacteria can exchange DNA and that when they do certain traits, such as the ability to cause disease in humans, can be passed from one strain of bacteria to another. Scientists also learned that when a virus infects a cell it injects its DNA into the cell, which then produces many copies of the virus, suggesting that DNA contains instructions for building viruses.
People began to think that genetic information might be written in the differences between the DNA bases of different species. A DNA molecule is a double helix, a structure that looks much like a ladder twisted into a spiral. The sides of the ladder are made of alternating sugar and phosphate molecules, the sugar of one nucleotide linked to the phosphate of the next.
DNA is often said to have a sugar and phosphate "backbone. Each rung of the ladder is made of two nitrogenous bases linked together in the middle. Sometimes, this unit of measurement is shortened simply to "bases.
By the time they began their work in the early s, it was clear that DNA is the hereditary material, and scientists were racing to find out more about the long-ignored molecule, picking apart the implications of each new detail. Everyone knew they couldn't really understand how DNA works until they understood how its nucleotide building blocks are put together.
In humans, genes vary in size from a few hundred DNA bases to more than 2 million bases. An international research effort called the Human Genome Project, which worked to determine the sequence of the human genome and identify the genes that it contains, estimated that humans have between 20, and 25, genes.
Every person has two copies of each gene, one inherited from each parent. Most genes are the same in all people, but a small number of genes less than 1 percent of the total are slightly different between people. Alleles are forms of the same gene with small differences in their sequence of DNA bases. Scientists keep track of genes by giving them unique names. Because gene names can be long, genes are also assigned symbols, which are short combinations of letters and sometimes numbers that represent an abbreviated version of the gene name.
For example, a gene on chromosome 7 that has been associated with cystic fibrosis is called the cystic fibrosis transmembrane conductance regulator; its symbol is CFTR.
DNA is just as a cookbook recipe for the synthesis of proteins in the cells. Most of the things in our body are made up of proteins such as bones, teeth, hairs, earlobes, blood, muscles. Hence, they are considered as building blocks of the body. Proteins are essential for our body to work properly, the growth of our body, and to stay healthy. It is estimated by scientists that each gene makes as many as 10 different proteins in the body.
It goes up to , proteins. Working of a gene can be explained with an example - Neera's mother has one gene for brown hair and one for red hair. She passed the brown hair gene to Neera. Neera's father has two genes for brown hair. Neera ended up with two genes for brown hair, one from each of her parents.
The information encoded in a gene is used in the synthesis of a functional product like protein, and the process is known as Gene expression. This is known as central Dogma. Structural genes are those genes that code for the amino acid sequences.
There are two stages involved in the process of gene expression. It is the process in which mRNA is used to direct protein synthesis and also for the subsequent post-translational processing of the protein molecule. Other forms of RNA that play a role in transcription can also be produced by some genes.
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