BiologyClassroom
What is a Gene? Are DNA & GENE one and the same?
Almost! Simply put, Genes are made up of DNA. Lets take a closer look and find out.
DNA ( Deoxyribonucleic acid) is a biomolecule that is found inside the nucleus of every cell ( there are a few exceptions ) of all living organisms. This molecule is made up of ribose sugar which is nothing but a 5 carbon sugar, phosphate group and nitrogenous bases. Now these nitrogenous bases are really important because they are the ones that code for proteins. In other words they are the building blocks of the DNA molecule. The sequence in which they get arranged is what gives meaning to the DNA. i.e. their sequence represents what is called the genetic code.
Lets take a closer look at these bases or nucleotides as they are called.
There are 4 bases namely Adenine ( A) , Guanine ( G), Thymine (T) and Cytosine ( C) . These are the 4 letters of the GENETIC ALPHABET system that determine what we look like , how tall we are, what our skin colour is and other ’n’ number of genetic traits. These four letters A, T, G and C can be arranged on the DNA in 64 combinations of three letter words. Each of these three letter words convey a meaning. That is they represent the Genetic code. Genetic code is the language by which the information for making proteins is recorded in the DNA. A set of codes that represent the information for making a complete protein molecule is called GENE. A simple way of saying this would be ‘ Gene is a segment of the DNA that code for a protein’.
Although I must mention here that DNA also codes for RNA molecules. Not proteins directly. And also readers must note that the GENETIC CODE is found on a particular type of RNA molecule called messenger RNA (mRNA). This mRNA however is made from copying the information present on what is called the template DNA. Hence we can venture to say gene is found on the DNA. Nonetheless the DNA cannot and does not make proteins directly. It makes a mRNA copy of its genetic information and sends it out to the cytoplasm for being processed into a protein , a process which we call TRANSLATION.
To give an idea of what DNA is and what gene is consider the following.
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ACATCHASESTHERATTHERATRUNSINTOAHOLE
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A CAT CHASES THE RAT THE RAT RUNS INTO A HOLE
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A CAT CHASES THE RAT. THE RAT RUNS INTO A HOLE.
Consider the first string of letters. Its akin to the 4 letter genetic alphabet of the DNA. Although it doesn’t look meaningful when we look at the second statement we find that it conveys something. This grouping of letters into meaningful words is similar to the way GENETIC CODE works. The last statement has two sentences separated by a full stop. Each sentence has its own complete meaning. Each of these sentences represents a GENE.
However the real genetic code has no gaps between two codes like the spaces we show here between words. In reality Genetic code and letters in it have no spaces or full stops. This example using the English alphabets has been given to help the readers understand what is gene and what is DNA.
Find this article on ‘Medium’ : https://medium.com/@soundarya.uthaman/what-is-a-gene-are-dna-gene-one-and-the-same-a9b75d4403c8