- While DNA encodes instructions to build life, RNA molecule read and act on the information.
- It simply copies the instruction and carry it to other parts of the cells to make proteins.
- Recent understanding has shown RNA has much bigger role than acting as a messenger. (more on this later)
- In terms of molecule, the only difference in RNA is an extra OH group which makes is unstable.
- Thus, the major difference between DNA and RNA is that while DNA is more permanent RNA is not permanent.
- The central dogma of molecular biology explains the how genetic information flows from DNA to proteins.
- This simply describes how the code of life is brought to life.
- This happens in two-stages called transcription and translation.
- In short DNA is transcribed into RNA which is then read by ribosome to make Proteins which are the building blocks of life.
- Note that advancements in biotechnology coincide with the increased understanding of the central dogma.
Central dogma (cookbook analogy)
- Consider DNA to be a cookbook of recipes for making proteins. Transcription is the process of photocopying the recipe. This is done by mRNA, short for messenger RNA, inside the nucleus.
- Once copied the recipe mRNA goes outside the nucleus to the chef, called ribosome.
- There is also a translator, tRNA who translates mRNA recipe to rRNA of the ribosome which then makes amino acids, the building blocks of proteins.
- A block of 3 letters in the mRNA correspond to ‘cooking’ of 1 amino acid.
- Each 3-letter base in mRNA that is read by tRNA that correspond to one amino acid is called ‘codon’.
- Many amino acids come together to form the primary structure of protein.
- The primary structure is twisted and folded to make a 3-d structure of protein.
- The coding part of protein are called as genes.
- According to recent understanding there are about 20500 genes in human genome.
- Genes vary in complexity. They range in size from few hundred bases to more than 2 million.
- 98% of the genome is non-coding regions.