Moving to the part of the animation that takes place in the nucleus, which molecule is shown as pale blue/green?

Complete question:

Visit http://www.genomicseducation.ca/animations/gene_expression.asp and  play the animation.

Moving to the part of the animation that takes place in the nucleus, which molecule is shown as pale blue/green?

snRNA molecules

Explanation:

snRNA means small nuclear RNA. These are small RNA molecules found in the nucleus and are involved in the RNA maturation process. In association with proteins, they compose the spliceosomes. They are involved in the processing phase of preRNA, which must maturate before its exportation from the nucleus as mRNA.

preRNA molecules are the first RNA transcribed and possess long intermediate sequences called introns that do not codify proteins. On the contrary, the encoding sequences are called exons.

Introns and exons alternate in the molecule, and the limit between them is called the splice site. Depending on the extreme we are looking at, they are 5´splice site or 3´splice site. Essentially, snRNA places in these sites and connects all the exons extremes of the preRNA, splicing out the introns. They remove the sequences that are not useful during the protein synthesis. This removal occurs before the RNA leaves the nucleus. Once the introns are excised the exons join to form the unique mature mRNA. This process is known as the splicing mechanism and turns preRNA into mRNA.        

Note: In the attached files, you will find some fragments of the animation with the respective labels.