Cell Features
...are different types of proteins in the cell membrane. Each type plays a vital role in the life of a cell. Marker proteins, which are attached to a carbohydrate on the cell’s surface, help other cells recognize their cell type—liver cell or heart cell, for example. Receptor proteins recognize and bind to specific substances, such as signal molecules, outside the cell. Various enzymes in the cell membrane are involved in important biochem-ical reactions in the cell. Transport proteins aid the movement of substances into and out of the cell. 1. The first paragraph describes a cause-and-effect relationship between the structure of a membrane protein and the lipid bilayer. The cause in this relationship is the nonpolar middle part of a membrane protein. What is the effect? It is repelled by the water on either side of the lipid bilayer. 2. Another cause-and-effect relationship detailed in the first paragraph explains that the inner and outer parts of a membrane protein are attracted to water. What is the cause? The inner and outer parts of the protein are mostly polar. Type of protein. Function 6/7. Mark...