The motor protein then detaches from the filament and changes back to the original conformation. Movement of the filament is work, the energy for which comes from ATP hydrolysis by the motor protein. Actin was first found in muscle tissue. Surprisingly, actin is also found in plants. Actin is required for cytoplasmic streaming, the movement of organelles within the cytosol of a cell.
Polysaccharides are an important part of the eukaryotic plasma membrane.
Polysaccharides found as part of the cell membrane were originally attached to lipids and membrane proteins back in the RER and Golgi. Describe two structural features of proteins that allow them to cross a phospholipid bilayer. These structures are each maintained by hydrogen bonds between amino acids and by hydrophobic interactions between nonpolar amino acid residues and the nonpolar hydrocarbon chains of phospholipids in the middle of the bilayer. List three examples of ways in which cells maintain steep concentration gradients. Molecules can be produced at one location within a cell and used in another location in the cell, establishing a concentration gradient in the cytosol between the two regions.