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;
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Answer:
The correct answer is - the large cross-sectional area and greater length of the cytoplasmic core get less resistance than the smaller cross-sectional area.
Explanation:
The greater length and the large cross-sectional area of the cytoplasmic path or core get less resistance than the resistance of the current path which is the small cross-sectional area of axoplasm. This leads it to greater resistance than the resistance of the current path through the extracellular fluid.
Other than this there is also an unequal distribution of the ions that leads to the increase in potential difference as higher Na+ ions present in cytoplasm and high amount of K+ ion present in axoplasm.
Species diversity hurts ecological succession. Explanation: Species diversity does not contribute for ecological succession. The diversity among the species is high at pioneer community. However as time passed competition and interaction causes a significant drop in species diversity.