I believe it is the crust
The sun.........................................................
Answer:
Regulatory sites e.g enhancers and silencers
Explanation:
Gene expression involves the synthesis of gene products usually proteins and RNA. However, a certain product might not be needed at all or in small quantity. Gene regulation mechanism is the process that makes this happen. Gene regulation is the mechanism that acts to induce or repress the expression of a gene.
Gene regulation involves controlling the rate and manner of gene expression which is achieved through a set of regulatory proteins called transcription factors. Transcription factors bind to specific regulatory nucleotide sequences and help to turn "on or off" specific genes in the DNA.
Transcription factors can either be ACTIVATORS or REPRESSORS depending on whether they boost or inhibit gene expression. The binding sites for these regulatory proteins called TRANSCRIPTION factors are the regulatory nucleotide sequences on the DNA called enhancers and silencers.