Question

Proteins are large molecules. They enter a cell through

A. passive transport
B. active transport
C. diffusion
D. osmosis

Answer 1

A. Passive transport: Large molecules are 'helped' through the membrane. This is known as facilitated diffusion(passive transport). The 'facilitators' are carrier proteins. These have specific binding sites for the substances they transport. Randomly moving particles in solution come into contact with their specific binding site. Once they have become bound the protein changes shape and the particle is released on the other side of the membrane.

Answer 2

hope that helps :)