Question

Primitive cells based on RNA and lipids as the major components, will not have proteins to help move necessary molecules across the cell membrane for growth and reproduction. What is the plausible solution offered for this dilemma in the lecture by the speaker?

1) There are lipid vesicles that carry the nutrients that fuse with cell membranes
2) The explosive conditions of the environment send nutrient projectiles into cells
3) There is DNA embedded in the membrane that helps carry molecules in or out
4) The lipid barrier is not perfect and allows crucial molecules to move in or out
5) None of the statements are discussed

Answer 1

The most plausible solution to how primitive cells transported necessary molecules across their membrane is that the imperfect lipid barrier allowed crucial molecules to move in or out through passive diffusion, which does not require proteins.

Step-by-step explanation:

The dilemma of how primitive cells based solely on RNA and lipids would transport necessary molecules across their membrane, given the absence of proteins, can be addressed by considering the innate properties of the cell membrane and the passive transport processes.

The cell membrane is a phospholipid bilayer that is selectively permeable, allowing small and nonpolar molecules to diffuse through it passively. This passive diffusion is driven by the concentration gradient of the molecules, enabling them to move from areas of high concentration to low concentration. Although primitive cells lacked proteins for facilitated transport, the lipid barrier's imperfect nature would have allowed essential molecules to move in or out, supporting growth and reproduction.

Thus, the most plausible answer from the options provided is: The lipid barrier is not perfect and allows crucial molecules to move in or out. Proteins and DNA were not mentioned in the lecture as part of primitive cell membranes allowing transport, nor were explosive environmental conditions or vesicles. This basic mechanism of passive transport aligns with the rudimentary structure and functionality of the earliest cells.