In translation and transcription, what are the functions of mRNA, tRNA and rRNA?

Question

Translation has different tasks for the RNA molecules than Transcription.

Answer 1

Okay, first of all, let's differentiate between DNA replication, transcription and translation.

DNA replication is the process whereby DNA makes an exact replica of itself. In this process, double stranded DNA is first unwound by the enzyme helicase, and each strand of the DNA serves as a template for the building of its complementary strand (at this point, free nucleotides are attached together in order to build the complementary strand - DNA polymerase is the enzyme that takes care of this). Afterwards, the enzyme ligase binds the two original strands to their two newly built complementary strands to give us 2 identical double stranded DNA.

Transcription is the process whereby RNA is produced. As was the case with DNA replication, a double stranded DNA molecule is unwound, but this time only 1 strand gets its complenetary strand built, and that complementary strand becomes an RNA strand (remember that RNA is a single stranded molecule). Also important to note is the fact that for all A's on the single strand of DNA, we get U (uracil) on the RNA strand when the nucleotides are base pairing.

Translation is the process whereby RNA (or more specifically, mRNA, tRNA and rRNA) build a protein. All of the three different types of RNA I mentioned are made inside the nucleus. They then leave the nucleus through the nuclear pores and go to the ribosome. rRNA (ribosomal RNA) attaches to a ribosome and makes it function (the exact manner in whcih this is carried out is unknown - some say rRNA acts as an enzyme when it's attached to a ribosome).

mRNA (messenger RNA) is carrying out the actual code to build the protein (i.e., it has the nucleotide bases - and as you should know, each three consecutive bases, also called a codon, code for a particular amino acid). mRNA attaches to the ribosome as well, and lastly, tRNA (transfer RNA) reads off the code on mRNA and goes into the cytoplasm to pick up the amino acid the mRNA codes for, and brings them back to the ribosome, where amino acids are attached together in the sequence that will yield the protein that is to be built.

Remember that proteins are simply polymers of amino acids, that means proteins are made up of amino acids attached together - and the order in which the amino acids are attached together is peculiar to a particular protein.

Answer 2

Transcription is the formation (polymerization) of RNA on the DNA template according to the base pair rule and complementarity. All kinds of RNA are transcribed from the respective DNA stretches. In other words, all RNAs are born during transcription. They don’t do anything over there. They move to the cytoplasm where they have to play specific roles.
In translation, however, all the three types of RNA have a role to play. mRNA contains codons in the form of triples of bases. rRNAs serve to maintain the integrity of the ribosome and help mRNA attach to attach to the ribosome. tRNA brings along a specific amino acid to the ribosomal site as per base pair rule, which means according to anticodon- codon matching to enable the formation of peptide bond between the amino group of one amino acid and the carboxyl group of the adjacent amino acid.

Answer 3

RNAm is produced from the original DNA inside the nucleus this is transription. The mRNA then gets out of the nucleus and goes to bind with a ribosome. Ribosomes are made of rRNA wich allows the RNAm to bind with the complementary basis of the rRNA. Then the tranlation starts. The tRNAs come to bind inside the Ribosome bringing amino acids with them. Then a protein is complete.