Answer:
The Core
Explanation:
The very center of the earth is called the core.
I think should do the trick A and D
When a nerve impulse reaches the end of an axon, the axon releases chemicals called neurotransmitters. This would make the answer be.... A. a chemical signal is released
Explanation:
Differentiation in cells occurs due to the silencing of some genes in the DNA of the cell while leaving others open to RNA polymerase enzymes.
Silencing occurs through the mediation of histones that tightly coil up DNA into heterochromatin in some regions. This way the genes in these regions are inaccessible to transcription enzymes and proteins and cannot be expressed. This means that proteins associated with these genes are not produced.
The open genes, on the other hand, in the euchromatin region, produce the necessary proteins that are associated with the determined function of the cell.
An example is that while the hepatocytes cells and brain cells of the same person have the same DNA, the genes for producing bile are silenced in the brain cells (and are open in hepatocytes) while genes responsible for producing neurotransmitters are silenced in hepatocytes but open in brain cells.
Learn More:
For more on gene silencing check out;
brainly.com/question/12777212
brainly.com/question/4768354
brainly.com/question/10225586
#LearnWithBrainly
