Ribonucleic Acid (RNA) - are molecular strands containing information encoded within sequences of nucleotides, which have been read and copied from a DNA strand via a process called Transcription.

The string of complimentary nucleotides produced by transcription are the RNA molecule. RNA is similar to one side of a DNA molecule in structure, but in RNA, the nucleotide containing thymine (T) is replaced with a nucleotide containing uracil (U). Also the sugar used in the "backbone" part of the molecule is ribose instead of 2-deoxyribose

In biological entities, RNA molecules hold stored sequences of instructions, which are followed by specialized molecular machinery in the cell. The molecular machines that follow the instructions stored in RNA, use those instruction to construct specific three-dimensional protein components and assemblies. The protein-assemblies produced are then used to produce all biological function-blocks, and substances. Each protein is assembled from the 20 amino-acids. As stated, the protein-assemblies are then used as components of all molecular machinery, including the molecular-machines that produce these components from RNA-conveyed instruction sequences.



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mRNA

Messenger RNA (mRNA) is used to make a copy of specific assembly instruction sequences to be followed by ribosomes the protein-producing work-areas within the cell.

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tRNA

Transfer RNA (tRNA) carries individual amino-acids to a ribosome for inclusion in whatever protein-sequence is being synthesized. Each tRNA matches a given codon (a contiguous sequence of three nucleotides on the mRNA strand that corresponds to a specific amino-acid).

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rRNA

Ribosomal RNA. Many portions of a ribosome are composed, not of proteins, but of RNA. These RNA sub-sections often function to coordinate and handshake with other extrernal RNA structures that interact with the ribosome during protein synthesis (e.g., tRNA). Though proteins are also needed in the construction of a ribosome, a considerable portion of their composition includes these special rRNA sequences. Like all RNA, rRNA compliment sequences are stored in the cell's DNA strand, and transcribed into RNA by a set of molecular machines designed for the transcription process.





"Protein synthesis (DNA transcription, translation and folding)"



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See Also:

• Protein Synthesis Animation Video
• Translation
• Protein Synthesis: Translation Process
• Interfering RNA (RNAi/siRNA) and some of the machines (dicer,slicer,RISC, etc.) associated with it (interesting).