07.1 Membrane Structure

What defines the boundary of a cell?

• Mitochondria

• Plasma membrane

• Cytoplasm

• Nucleus

What characteristic of the plasma membrane determines what enters and exits the cell?

• Permeability

• Impermeability

• Selectively permeable

• Semi-permeable

What model is used to describe the structure of the membrane?

• Fluid mosaic model

• Dynamic model

• Solid model

• Rigid model

What are the two main components of cell membranes?

• Nucleic acids and carbohydrates

• Proteins and nucleic acids

• Carbohydrates and lipids

• Phospholipids and proteins

What type of fatty acid tails in phospholipids contribute to a more fluid membrane?

• Trans fats

• Unsaturated

• Saturated

• Hydrogenated

What does amphipathic mean in the context of phospholipids and proteins?

• Only hydrophilic

• Only hydrophobic

• Both hydrophobic and hydrophilic

• Neither hydrophobic nor hydrophilic

What is the role of cholesterol in the membrane?

• Decreases fluidity at moderate temperatures

• Increases fluidity at moderate temperatures

• Replaces phospholipids in cold temperatures

• Acts as a primary structural component

What distinguishes peripheral membrane proteins from integral membrane proteins?

• Peripheral proteins are found near the membrane but not embedded

• Peripheral proteins are embedded within the membrane

• Integral proteins do not interact with the membrane at all

• Integral proteins are found only on the surface of the membrane

What type of molecules are always found on the extracellular side of the membrane?

• Phospholipids

• Polysaccharides

• Nucleic acids

• Amino acids

What prevents membrane phospholipids from flipping sides?

• Hydrophilic interactions

• Covalent bonds

• Hydrophobic interactions

• Ionic bonds