Answer:
It only allow certain material to enter the cell
Its 18 electron
1st orbital : maximum = 2 electrons
2nd orbital : maximum = 8 electrons
3rd orbital : maximum = 8 electrons
2+8+8 = 18 electrons
DNA supercoiling means under or over winding of the DNA strand and basically is to become more condensed and more organized. Supercoiling is very important as it compacts the genetic code and as if that was not enough supercoiling also regulates and oversees the access the the genetic code.
<span>A lunar eclipse occurs when the Earth passes between the Moon and the Sun, and the Earth's shadow obscures the moon or a portion of it. A solar eclipse occurs when the Moon passes between the Earth and the Sun, blocking all or a portion of the Sun. </span>