Question

PART A) Which statement is false? A) Amphipathic molecules may form micelles rather than bilayers, depending on their structures.   B) All biological membranes contain lipids.

C) Biological membranes typically contain proteins. D) All biological membranes have the same composition.

PART B) Which statement is true? A) Once a membrane is synthesized, the lipid composition of each monolayer does not change. B)Hydropathy analysis provides a measure of H-bonding within the transmembrane portion of a membrane-spanning protein. C)Proteins may be embedded in, but never span, a biological membrane. D)For all glycoproteins of a plasma membrane, the glycosylated domains are always found on the extracellular face of the bilayer.

PART C) Which statement is true? A)Lipid bilayers are essentially impermeable to polar solutes. B)The fluid mosaic model considers biological membranes to be a sea of lipids floating in the aqueous fluid of the cytoplasm. C)Membrane phospholipids always comprise the majority (by weight %) of a cell membrane. D) All membranes in a given cell have the same lipid composition.

Answer 1

PART A) D) All biological membranes have the same composition is false.

The components of all biological membranes mainly consist of proteins, lipids, and carbohydrates in different proportions. Even though the components are the same, the composition of each component will be different. For eg. In plasma membranes, mitochondrion and bacterial cells the weight ratio of lipid to protein is different.

PART C) A)Lipid bilayers are essentially impermeable to polar solutes is true.

A higher degree of hydration and charge of polar solute prevent them to enter into the bilayer.