The phospholipid bilayer is composed of fats with Hydrophobic core. If protein channels were absent in the cell membrane, would water soluble nutrients be able to enter or exit the cell? Explain in terms of the composition of the plasma membrane. In your own words, explain the fluid mosaic model proposed by Singer and Nicholson.

Without the nuclear membrane the cell would collapse and die. Without the cell membrane, any chemical would be allowed to enter. Membranes are very important because they help protect the cell. Materials move across the membrane by diffusion.

the sugar-phosphate backbone forms the structural framework of nucleic acids, including dna and rna. this backbone is composed of alternating sugar and phosphate groups, and defines directionality of the molecule.