Chapter 5: The Plasma Membrane Functions Quiz

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What is the main function of the plasma membrane?

Enclosing the cell and defining its boundaries (correct)

Maintaining the characteristic differences between organelles and cytosol

Creating a barrier that is permeable to most water-soluble molecules

Determining the size and shape of the cell

What is the common general structure of biological membranes?

A continuous single layer of lipid molecules

A thin film of lipid and protein molecules held together mainly by non-covalent interactions (correct)

A rigid and non-dynamic structure with fixed molecules

A double layer of lipid and protein molecules held together by covalent interactions

What distinguishes the functions of cytomembranes in eukaryotic cells?

They determine the size and shape of the cell

They are impermeable to most water-soluble molecules

They maintain the characteristic differences between the contents of each organelle and the cytosol (correct)

They enclose the cell and define its boundaries

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 Signup and view all the answers

Which type of molecules do lipid layers serve as a barrier to?

Most water-soluble molecules Signup and view all the answers

What is a function of biological membranes?

Maintaining essential differences between the cytosol and the extracellular environment Signup and view all the answers

What is the function of protein molecules that span the lipid bilayer in the membrane?

Transporting specific molecules across the membrane Signup and view all the answers

What is the mean thickness of the plasma membrane as defined by the electron microscope (EM)?

8.5nm Signup and view all the answers

What covers the outer side of the plasma membrane in animal eukaryotic cells?

Cell-coat or glycocalyx Signup and view all the answers

What is the chemical composition of a plasma membrane isolated and purified from red blood cells (RBC)?

42% proteins, 50% lipids, 8% carbohydrates Signup and view all the answers

What are the main components of the membrane lipids found in the plasma membrane?

Phospholipids, sterols, and glycolipids Signup and view all the answers

Which molecule forms the framework (bilayer) of the membrane and is the most numerous of the membrane lipids?

Phospholipids Signup and view all the answers

What are the main phospholipids observed in the plasma membrane of mammals?

Phosphatidylethanolamine, phosphatidylserine, phosphatidylcholine, sphingomyelin Signup and view all the answers

In terms of chemical composition, how do cytomembranes differ from plasma membranes?

Contain more protein, less lipids, and no cell-coat Signup and view all the answers

What are amphiphilic molecules in the context of membrane lipids?

'Water-loving' or polar headgroup molecules Signup and view all the answers

What characterizes phospholipids and sterols found in the plasma membrane?

'Water-loving' or polar headgroup and 'water-fearing' or non-polar tail Signup and view all the answers

Chapter 5: The Plasma Membrane Functions Quiz

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