A. Describe the role of the promoter in eukaryotic gene expression. Explain how a negative regulatory molecule could inhibit transcription at the promoter. B. Identify TWO events that occur during RNA processing. Explain how RNA splicing increases the variation of mRNA molecules.

C. Describe the role of miRNA in gene expression.

Explanation:

A. The role of promoter in eukariotic gene expression is It is to bind transcription factors that regulate transcription initiation. This molecule is so important because control the binding of RNA polymerase to DNA. The promoter region may be short or very long; the longer the promoter is, the more protein binding space is available. A negative regulatory molecule has the possibilty to inhibit transcription at the promoter because these molecule block the binding of RNA polymerase to the promoter region, thus not allowing the initiation of transcription, in some particular cases the negative regulator binds to the lac repressor and will bind to the promoter in the same site where RNA polymerase would bind to.

B. Two process that occurs during RNA processing are RNA splicing and 5′ capping, 3′. RNA splicing is a process known for removing the introns from the pre-RNA and stuck back together the restant parts, exons. This process has as a goal form a mature mRNA that does not contain the intron sequences. RNA splicing has an effect on the variation of mRNA molecules because through a process called alternative splicing more than one mRNA can be made from the same gene. 

C. Even though they are not quite the same thing miRNA and negative regulatory molecules have the same role, which inhibits the translation and silence genes. They regulate gene expression by binding to the 3'-UTR of their target mRNAs and destabilizing the mRNA and translational silencing, repressing protein production. Even so, under specific circumstances, miRNA can activate translation or regulate transcription.

if the type of the food available changes, then the frequency of beak types will change, because birds with beaks more suited to the available food will be more successful over time.

during the process of dna replication, brdu can replace thymidine and incorporate into the newly synthesized dna, cell proliferation thus can be reflected in the extent of brdu incorporation.