16 Questions
What is the main function of the plasma membrane?
Enclosing the cell and defining its boundaries
What is the common general structure of biological membranes?
A thin film of lipid and protein molecules held together mainly by non-covalent interactions
What distinguishes the functions of cytomembranes in eukaryotic cells?
They maintain the characteristic differences between the contents of each organelle and the cytosol
What is a key characteristic of cell membranes?
They are dynamic, fluid structures, with most molecules able to move about in the plane of the membrane
Which type of molecules do lipid layers serve as a barrier to?
Most water-soluble molecules
What is a function of biological membranes?
Maintaining essential differences between the cytosol and the extracellular environment
What is the function of protein molecules that span the lipid bilayer in the membrane?
Transporting specific molecules across the membrane
What is the mean thickness of the plasma membrane as defined by the electron microscope (EM)?
8.5nm
What covers the outer side of the plasma membrane in animal eukaryotic cells?
Cell-coat or glycocalyx
What is the chemical composition of a plasma membrane isolated and purified from red blood cells (RBC)?
42% proteins, 50% lipids, 8% carbohydrates
What are the main components of the membrane lipids found in the plasma membrane?
Phospholipids, sterols, and glycolipids
Which molecule forms the framework (bilayer) of the membrane and is the most numerous of the membrane lipids?
Phospholipids
What are the main phospholipids observed in the plasma membrane of mammals?
Phosphatidylethanolamine, phosphatidylserine, phosphatidylcholine, sphingomyelin
In terms of chemical composition, how do cytomembranes differ from plasma membranes?
Contain more protein, less lipids, and no cell-coat
What are amphiphilic molecules in the context of membrane lipids?
'Water-loving' or polar headgroup molecules
What characterizes phospholipids and sterols found in the plasma membrane?
'Water-loving' or polar headgroup and 'water-fearing' or non-polar tail
Test your knowledge about the functions and importance of the plasma membrane in cell biology. Learn about the role of the plasma membrane in defining cell boundaries, maintaining differences between the cytosol and the extracellular environment, and determining cell size and shape.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
