Question

If a different chemical than phospholipids can form membranes, what characteristics would you expect it to have to be an adequate basis for life? If such a chemical exists, consider the characteristics of the chemical, how it would interact with itself and molecules in its environment, and the ultimate structure of the membrane. Make a list of these characteristics.

Answer 1

If a different chemical than phospholipids can form membranes, it must has following characteristic to be an adequate basis for life-

• This chemical should be amphipathic in nature as phopholipid is i.e. one end of chemical is attracted to water and the other repels water. When this molecule is submerged in water, as they will be in living cells, this property automatically forces the molecules into an alignment that creates a natural water barrier. This barrier functions as the outer membrane of a cell, which allows for cell specialization and cooperation.
• This chemical should form the outer cell membrane and help the cell to maintain its internal structures as done by phospholipids. Phospholipids form the outer cell membranes that hold the cytoplasm within the cell. This membrane is semi-permeable, which means it is selective about what enters and exits the cell. The cell membrane also surrounds the intracellular structures, such as the mitochondria. Phospholipids help the cell maintain its internal structures and environment, a process called homeostasis. The semi-permeable nature of the phospholipid bilayers allow the free diffusion of small molecules, such as oxygen, hydrocarbons and carbon dioxide. It prevents the diffusion of larger molecules, such as glucose, water and charged ions. The chemical should be semi-permeable in nature.

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