• In eukaryotes, RNA is formed from DNA -present in the nucleus, mitochondria, and chloroplasts.

• Let's consider the RNA coming from the core.

• There are three modes of RNA: messenger, ribosomal, and transporter.

• Each of these types is formed from different stretches of DNA molecules.

Ribosomal RNA

• It is related to a segment of some DNA molecules, along with which the nucleole is formed.

• Ribosomes are organoids consisting of two subunits of different sizes, composed of proteins and large amounts of ribosomal, which correspond to more than half of the mass of this organoid.

• Thus, ribosomal is a component of ribosome structure.

Messenger RNA

• Messenger RNA is what transmits information from DNA to ribosomes, guiding the synthesis of a given protein.

• The segment of DNA-that serves as a mold for the production of MNA- corresponds to a gene.

• RNA transporter RNA transporter is also called soluble RNA. Its function is to carry a specific amino acid, which is dissolved in the cytosol, to the ribosomes -which perform protein synthesis.

Other nucleic acids.

• There are several other types of RNA with distinct functions. There are, for example, RNA molecules that act as catalysts and are called ribozymes.

• Viral nucleic acids can have many variations concerning the pattern described.

• Thus, some viruses have DNA with a chain, RNA with two chains, and RNA with replication capability.

Genetic code

• A messenger RNA molecule binds to ribosomes and guides the synthesis of a given protein.

• Messenger RNA has a nucleotide sequence, the variable part of which is nitrogen bases.

• The mRNA presents a sequence of nitrogen bases. The protein, in turn, has a sequence of amino acids.

• What is the connection between these sequences: mRNA bases and protein amino acids? Scientists Khorana and Nirenberg experimentally established the following relationship: three nitrogen bases of a messenger RNA molecule correspond to an amino acid that integrates a protein chain; is a ratio of 3 to 1. A trio or a crack of messenger RNA bases corresponds to a codon, which usually corresponds to an amino acid.

• The first match discovered was from the UUU bases trio, which corresponds to the amino acid phenylalanine. The correspondence between codons and specific amino acids is the genetic code.

• The genetic code is universal. That is, it is the same for virtually all living beings.

• Thus, UUU color responds to the amino acid phenylalanine in humans, a whale, daisy, or a bacterium. The universality of the genetic code is what makes it possible to insert human genetic material into a bacterium so that it can synthesize a human protein, such as insulin.

• Only in some cases the cracks of messenger RNA correspond to different amino acids; this occurs, for example, in certain protozoa and some yeasts. The universality of the genetic code is one of the central evidence of the common origin of all living beings. There are 64 possible cracks. However, living beings have 20 types of amino acids. Thus, there are more codons than amino acids to be identified.

• What happens is that different codons can identify the same amino acid. These codons would function as "synonyms" because they are expressed in the same amino acid. That is, different codons would encode the same amino acid. Because of this, we say that the genetic code is degenerate.

• For example, UUU corresponds to phenylalanine, but the UUC codon also corresponds to that amino acid.

• Some codons don't correspond to any amino acids.

• They are of great importance in controlling protein synthesis.

Synthesis process

There are codons to stop the synthesis process:

• This is the case of the UGA, UAG, and UAA codons.

• There is also a codon that identifies the beginning of the process.

• All protein begins to be synthesized with the introduction of the amino acid methionine, whose codon is AUG.

• Subsequently, methionine from the beginning is removed from the protein molecule formed.