It has an alternating chemical phosphate and sugar backbone, making the ‘sides’ of the ladder.
<span>(According to Reference)
Whereas an onion epidermal cell has a cell wall, a human cheek cell does not. Instead, a semi-permeable membrane surrounds the cytoplasm of the cheek cell. While there are chloroplasts present in onion cells, they are absent in cheek cells. </span>
An eon is 1.05 billion years and an era is 350 million years
