tRNAs and ribosomes (article) | Translation | Khan Academy
This article describes the three main types of RNA - messenger RNA (mRNA), ribosomal RNA (rRNA), and transfer RNA (tRNA). Translation requires some specialized equipment. Just as you wouldn't go to play tennis without your racket and ball, so a cell couldn't translate an mRNA into a. In cells, it can be divided into three categories: Ribosomal (rRNA), Messenger ( mRNA) and Transfer (tRNA). While all three types of RNA can.
Atypical base pairs—between nucleotides other than A-U and G-C—can form at the third position of the codon, a phenomenon known as wobble. Wobble pairing doesn't follow normal rules, but it does have its own rules. Rules like this ensure codons are read correctly despite wobble.
Wobble pairing lets the same tRNA recognize multiple codons for the amino acid it carries. The rules of wobble pairing ensure that a tRNA does not bind to the wrong codon. These codons specify leucine, not phenylalanine, so this is an example of how the rules of wobble pairing allow a single tRNA to cover multiple codons for the same amino acid, but don't introduce any uncertainty about which amino acid will be delivered to a particular codon.
Image modified from " Translation: You may be wondering: The answer may be that wobble pairing allows fewer tRNAs to cover all the codons of the genetic code, while still making that the code is read accurately. The 3D structure of a tRNA I like to draw tRNAs as little rectangles, to make it clear what's going on and to have plenty of room to fit the letters of the anticodon on there.
But a real tRNA actually has a much more interesting shape, one that helps it do its job.
However, the strand takes on a complex 3D structure because base pairs form between nucleotides in different parts of the molecule. This makes double-stranded regions and loops, folding the tRNA into an L shape. Each nucleotide consists of a five-carbon sugar, one or more phosphate groups, and a nitrogenous base. DNA has four types of nucleotides, each with a different nitrogenous base. RNA also has four types of nucleotides.
These nucleotides are similar to those of DNA, but contain a different sugar. Certain types of nucleotides can form hydrogen bonds with one another. These nucleotides can hydrogen bond with one another because their structures are complementary — that is, they fit together like chemical puzzle pieces. The formation of hydrogen bonds between nucleotide bases is called base pairing, and it plays an important role in many biological processes, including DNA replication and gene transcription.
One end of the tRNA binds to a specific amino acid amino acid attachment site and the other end has an anticodon that will bind to an mRNA codon. Different tRNAs have slightly different structures, and this is important for making sure they get loaded up with the right amino acid.
tRNAs and ribosomes
These sequences, in turn, are synthesized based on the sequence of nucleotides in DNA, specifically the section of the DNA called the gene which was used to synthesize the RNA strand during the base pairing process.
Function of mRNA Each molecule, or chain, of mRNA carries instructions on how to connect several "amino acids" into a peptide chain, which becomes a protein. The same way that nucleotides are building blocks for RNA, amino acids are building blocks for proteins.
Evolution has produced a "genetic code" wherein each of life's 20 amino acids is coded for by a series of three nitrogenous bases in RNA nucleotides.
The Three Roles of RNA in Protein Synthesis - Molecular Cell Biology - NCBI Bookshelf
Thus, each triplet of RNA nucleotides corresponds to one amino acid, and the sequence of nucleotides dictates the sequence of amino acids that will be linked into the peptide chain that makes a protein. While in some cases an amino acid can be represented by multiple nucleotide triplets, called codons, each codon on RNA represents only one amino acid.
For this reason, the genetic code is said to be "degenerate. Translation of the language of RNA into the language of protein is possible, because there are many forms of tRNA, each representing an amino acid protein building block and able to link with an RNA codon.
Thus, for instance, the tRNA molecule for the amino acid alanine has an area or binding site for alanine and another binding site for the three RNA nucleotides, the codon, for alanine. Translation Occurs in Ribosomes The process of translating RNA codon sequences into amino acid sequences and thus into specific proteins actually is called "translation. During translation, a strand of mRNA passes through a ribosome, like an old-fashion cassette tape moving through a tape reader.