What is the function of RNA?

Question

What is the function of RNA?

Answer 1

Ribonucleic acid or RNA is a nucleic acid made from a long chain of nucleotide units. Each nucleotide consists of a nitrogenous base, a ribose sugar, and a phosphate. RNA is very similar to DNA, but differs in a few important structural details .Functions are follows:

Messenger RNA (mRNA) is the RNA that carries information from DNA to the ribosome, the sites of protein synthesis (translation) in the cell. The coding sequence of the mRNA determines the amino acid sequence in the protein that is produced.[19] Many RNAs do not code for protein however. These non-coding RNAs can be encoded by their own genes (RNA genes), but can also derive from mRNA introns.[20] The most prominent examples of non-coding RNAs are transfer RNA (tRNA) and ribosomal RNA (rRNA), both of which are involved in the process of translation.[13] There are also non-coding RNAs involved in gene regulation, RNA processing and other roles. Certain RNAs are able to catalyse chemical reactions such as cutting and ligating other RNA molecules,[21] and the catalysis of peptide bond formation in the ribosome;[15] these are known as ribozymes.

[edit] In translation

Messenger RNA (mRNA) carries information about a protein sequence to the ribosomes, the protein synthesis factories in the cell. It is coded so that every three nucleotides (a codon) correspond to one amino acid. In eukaryotic cells, once precursor mRNA (pre-mRNA) has been transcribed from DNA, it is processed to mature mRNA. This removes its introns—non-coding sections of the pre-mRNA. The mRNA is then exported from the nucleus to the cytoplasm, where it is bound to ribosomes and translated into its corresponding protein form with the help of tRNA. In prokaryotic cells, which do not have nucleus and cytoplasm compartments, mRNA can bind to ribosomes while it is being transcribed from DNA. After a certain amount of time the message degrades into its component nucleotides with the assistance of ribonucleases.[19]

Transfer RNA (tRNA) is a small RNA chain of about 80 nucleotides that transfers a specific amino acid to a growing polypeptide chain at the ribosomal site of protein synthesis during translation. It has sites for amino acid attachment and an anticodon region for codon recognition that binds to a specific sequence on the messenger RNA chain through hydrogen bonding.[20]

Ribosomal RNA (rRNA) is the catalytic component of the ribosomes. Eukaryotic ribosomes contain four different rRNA molecules: 18S, 5.8S, 28S and 5S rRNA. Three of the rRNA molecules are synthesized in the nucleolus, and one is synthesized elsewhere. In the cytoplasm, ribosomal RNA and protein combine to form a nucleoprotein called a ribosome. The ribosome binds mRNA and carries out protein synthesis. Several ribosomes may be attached to a single mRNA at any time.[19] rRNA is extremely abundant and makes up 80% of the 10 mg/ml RNA found in a typical eukaryotic cytoplasm.[22]

Transfer-messenger RNA (tmRNA) is found in many bacteria and plastids. It tags proteins encoded by mRNAs that lack stop codons for degradation and prevents the ribosome from stalling.[23]

[edit] In gene regulation

Several types of RNA can downregulate gene expression by being complementary to a part of an mRNA or gene. MicroRNAs (miRNA; 21-22 nt) are found in eukaryotes and act through RNA interference (RNAi), where an effector complex of miRNA and enzymes can break down mRNA which the miRNA is complementary to, block the mRNA from being translated, or cause a promoter to be methylated which generally downregulates its gene.[24] Some miRNAs upregulate genes instead (RNA activation).[25] While small interfering RNAs (siRNA; 20-25 nt) are often produced by breakdown of viral RNA, there are also endogenous sources of siRNAs in plants.[26] siRNAs act through RNA interference in a fashion similar to miRNAs, including RNA activation.[27] Animals have Piwi-interacting RNAs (piRNA; 29-30 nt) which are active in germline cells and are thought to be a defense against transposons and play a role in gametogenesis.[28][29] Antisense RNAs are widespread among bacteria; most downregulate a gene, but a few are activators of transcription.[30] Antisense RNA acts by binding to an mRNA, forming double-stranded RNA that is degraded by enzymes.[31] There are many mRNA-like large non-coding RNAs that regulate genes in eukaryotes,[32] one such RNA is Xist which coats one X chromosome in female mammals and inactivates it.[33]

An mRNA may contain regulatory elements itself, such as riboswitches, in the 5' UTR or 3' UTR; these cis-regulatory elements regulate the activity of that mRNA.[34]

[edit] In RNA processing



Uridine to pseudouridine is a common RNA modification.Many RNAs are involved in modifying other RNAs. Introns are spliced out of pre-mRNA by spliceosomes, which contain several small nuclear RNAs (snRNA),[13] or the introns can be ribozymes that are spliced by themselves.[35] RNA can also be altered by having its nucleotides modified to other nucleotides than A, C, G and U. In eukaryotes, modifications of RNA nucleotides are generally directed by small nucleolar RNAs (snoRNA; 60-300 nt),[20] found in the nucleolus and cajal bodies. snoRNAs associate with enzymes and guide them to a spot on an RNA by basepairing to that RNA. These enzymes then perform the nucleotide modification. rRNAs and tRNAs are extensively modified, but snRNAs and mRNAs can also be the target of base modification.[36][37]

[edit] RNA genomes

Like DNA, RNA can be an information carrier. RNA viruses have genomes composed of RNA, plus a variety of proteins encoded by that genome. The viral genome is replicated by some of those proteins, while other proteins protect the genome as the virus particle moves to a new host cell. Viroids are another group of pathogens, but they consist only of RNA, do not encode any protein and are replicated by a host plant cell's polymerase.[38]

[edit] In DNA replication

Reverse transcribing viruses replicate their RNA genome by reverse transcribing DNA copies, which are later transcribed to replicate the genome for new virus particles. Retrotransposons also spread in this way,[39] and telomerase contains an RNA that is used as template for building the ends of eukaryotic chromosomes.[40]

Answer 2

The function of RNA depends upon the type of RNA and also the type of the organism (eukaryotic or prokaryotic).

The DNA of an organism, all eukatryotes and many prokaryotes, contain vital information required for protein synthesis. this information is "transcribed" into a type of RNA called mRNA aka messenger RNA. the mRNA takes this information into the cytoplasm.In the cytoplasm the mRNA settles on another type of RNA called rRNA, ribosomal RNA. this is the site of protein synthesis. a special type of RNA called tRNA,transfers RNA brings amino acids to this site of protein synthesis,to form proteins.

sometimes,instead of DNA, the RNA of many prokaryotes carry information for protein synthesis.

Answer 3

RNA is a natural polymer that is present in all living cells & that plays a role in protein synthesis.

Answer 4

RNA is the thingy that DNA changes to . It is the thing that provides the body with signs because the body cant read DNA. OR SOMETHING LIKE THAT :D