Gene and Genome

Many of us definitely must have listen to an important sentence in our life; it goes something like this "You look like your mom or dad." Or may be something similar like how you and your parent might behave or act in a same way. Have you ever wonder how we resemble so much like our parents and how our children resemble us? For years we have noticed that the offspring of an organism are startlingly similar and in some puzzlingly different. This is due to because of something that is in our bodies called genes.

Every living organism in this world have gene passed down through generation.

The word gene comes from the Greek word pangenesis coined by Charles Darwin in 1868. The word pangenesis means pan (whole) and genesis (birth) or genos (origin). It was not until the year 1909 when Wilhelm Johannes coined the word "GENE" to describe the fundamental physical and functional unit of heredity. However, it was the work of Gregor Mendel in the 1860s, who studied the heredity in pea plants that illustrated the theory that inherited traits are passed from one generation to the next in discrete units.

Gene is the unit of heredity which is transferred from a parent of any living organism to the offspring and it is held to determine some characteristics of the offspring. Genes are encoded in the DNA of chromosomes. Chromosomes consist of a single very long DNA helix. The encoded genes are located in the locus of the chromosomes.

Most genes encode protein and some produce non coding region RNA molecule. Protein and non coding RNA are known as the gene expression.

The two major steps to the overall of the gene expression, that have to be done to separate protein coding genes from its protein in all organisms are known as transcription and translation, respectively known as protein synthesis.

1. Transcription is the process where a DNA sequence is enzymatically copied by an RNA polymerase, which reads the template strand in the 3' to 5' direction and synthesis the RNA from 5' to 3' direction to produce a single stranded RNA molecule known as messenger mRNA. Transcription occurs in the nucleus, where the cell's DNA is sequestered; the RNA molecule produced by the polymerase is known as the primary transcript and must undergo post-transcriptional modifications before being exported to the cytoplasm for the next step translation.

2. Translation is the process where mRNA is converted to amino acid that forms proteins by the set of rules known as the genetic code. Translation occurs in the cytoplasm where the ribosomes are located. For the translation to proceed it first goes through activation where an amino acid is attached to tRNA by ester bond, the t-RNA gets charge and goes to the next step initiation. In initiation a small subunit of a ribosome is binded to the 5' end of the mRNA. Then elongation occurs where the charged tRNA binds to the ribosome along with GTP and an elongation factor. Finally, termination happens when the A site of the ribosome faces a stopcodon which causes the release of the polypeptide chain. These factors trigger the hydrolysis of the ester bond in peptidyl-tRNA and the release of the newly synthesized protein from the ribosome.

Some genes produce a non - coding RNA molecule that plays an important role in gene regulation. The most prominent example of a non - coding RNA are known as the transfer