What is a gene?

A gene is a lineal sequence of nucleotides of DNA or RNA, located in cell nucleus, essential to carry out a manifestation of an inheritable characteristic of an alive individual. In terms of structure, a gen is a fragment of a large molecule of DNA that storage information to fabricate a determined protein. This protein is the one who determine the corresponding character, as the eyes color, skin color, presence of seeds, resistance to a disease,...

Image 2.1. Image of a chromatide and the material contained on it, showing in an augmentated way, a gene (yellow)

Image 2.2. An image that shows
in yellow and red two different 
locus.

Usually, genes develop its function through transcription and translation. In some cases, although, can happen that a gene can make its function doesn't necessarily requiring this genetic processes. 

Each gene occupies a certain position in the chromosome called locus. And if you take into account the whole chromosomes of an individual we talk about the genome, as it is the set of genes of species.

To understand it easily, maybe is better to think of the DNA or RNA that form an individual (genome) as an ecnyclopedia, in which the nucleotides are the letters, the genes are the amount of chapters that compose the volumes created by the agrupation of letters in a determined way, and the chromosomes are the different volumes that form the encyclopedia.

Image 2.3. Gene sequence showing the nucleotides and each aminoacid formed

Who is the guilty of this vegetable crime?

There is no other culpable than Cucumovirus, which can be identified if looking to it  you are able to diferenciate a non-enveloped, spherical virion of about 29 nanometers in diameter, which has a T=3 icosahedral symmetry composed of 180 coat proteins: 12 pentamers and 20 hexamers.

Image 2.1. Picture about the real 
morfology of CMV

How this murderer is formed of?

It is not an easy question, and there must have being other researchs before answering this issue. His structure is formed of a segmented tripartite linear RNA composed of RNA1, RNA2 and RNA3. Each genomic segment is 3' tRNA-like structure and a 5' cap.

Image 2.2. Position of dierent RNA that compose the 
segmented tripartite linear virus RNA

This Cucumovirus expresses himself by using the RNA as a messager RNAs. Then, RNA1 and RNA2 encode proteins 1a and 2a, involved in the genome replication and internal transcription of sgRNA4 from the negative copy of RNA3. HRNA3 is translated into a movement protein, while sgRNA4 it translates to a capsid one. Apart from this, ORF2b, present at RNA2, encodes a viral supressor of RNA silencing.

How does it commit the crimes?

When the expression is done, virus expresses the protein 1st and 2nd to produce replication proteins, as I have mentioned before, on the viral factory and after it transcribes/replicates providing new ssRNA genomic (new viruses).

Everithing continues translating RNA4 that produces the capsid that envolves the ssRNA genome, and assemblying this virus particles.

Image 2.3. Picture of diferent viral factories for viruses

Finally, it is the turn of the viral movement protein, that triggers the information of tubular structures that mediate viron cell-to-cell transfer via a tubule-guided mechanism.