Gene Structure & Function | Post Transcriptional modification of mRNA | Lecture 8

Gene, unit of hereditary information that occupies a fixed position (locus) on a chromosome. Genes achieve their effects by directing the synthesis of proteins. The sequence of bases along a strand of DNA determines the genetic code. When the product of a particular gene is needed, the portion of the DNA molecule that contains that gene will split. Through the process of transcription, a strand of RNA with bases complementary to those of the gene is created from the free nucleotides in the cell. (RNA has the base uracil [U] instead of thymine, so A and U form base pairs during RNA synthesis).
This single chain of RNA, called messenger RNA (mRNA), then passes to the organelles called ribosomes, where the process of translation, or protein synthesis, takes place. During translation, a second type of RNA, transfer RNA (tRNA), matches up the nucleotides on mRNA with specific amino acids. Each set of three nucleotides codes for one amino acid.
The series of amino acids built according to the sequence of nucleotides forms a polypeptide chain; all proteins are made from one or more linked polypeptide chains. Genes always occurs in pairs just like chromosomes, Alternate form of gene is called allele, And the location of gene on chromosome is called locus.
Structure of Gene Gene consist of three parts,
1- Promoter region or promoter sequences,
2- Structural region consist of Exon and Intron
3- Terminator region where Gene ends Post Transcriptional modification of mRNA involves splicing of mRNA.
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