Plasma Membrane Structure and Function

The video covers the structure and function of the plasma membrane, focusing on the phospholipid bilayer and the fluid mosaic model. It explains the roles of integral and peripheral proteins, the impact of cholesterol on membrane fluidity, and the historical development of membrane theories, including the contributions of Goethe, Grendel, and Singer-Nicholson.

What is the primary structure of the plasma membrane?

• Cholesterol monolayer

• Phospholipid bilayer

• Double layer of proteins

• Single layer of phospholipids

Why is the plasma membrane described as a 'fluid mosaic model'?

• Because it is a solid structure

• Because proteins and cholesterol create a mosaic-like appearance

• Due to the rigid structure of phospholipids

• Because it is made of a single type of molecule

What role does cholesterol play in the plasma membrane?

• It forms the hydrophilic head of phospholipids

• It acts as a hormone receptor

• It regulates the fluidity of the membrane

• It makes the membrane more permeable

What is the difference between integral and peripheral proteins?

• Integral proteins are only on the outside of the membrane

• Peripheral proteins span the entire membrane

• Integral proteins span the membrane, while peripheral proteins do not

• Peripheral proteins are embedded within the membrane

Which of the following is a function of membrane proteins?

• They create a rigid structure

• They provide energy for the cell

• They act as hormone binding sites

• They form the phospholipid bilayer

How do pumps differ from channels in the plasma membrane?

• Pumps do not require energy, while channels do

• Pumps require energy, while channels do not

• Both pumps and channels require energy

• Neither pumps nor channels require energy

What was the initial theory proposed by Gorter and Grendel about the plasma membrane?

• It was a solid structure

• It was a single layer of proteins

• It was a bilayer of phospholipids

• It was a layer of cholesterol

What evidence helped disprove the Davson-Danielli model?

• The identification of a single protein layer

• The presence of only peripheral proteins

• The observation of protein movement within the membrane

• The discovery of cholesterol in the membrane

What did Singer and Nicolson propose about membrane proteins?

• They are only on the outer layer

• They are absent in the membrane

• They are embedded within the membrane

• They form a continuous layer

What technique involves freezing the membrane to study its structure?

• X-ray crystallography

• Freeze-fracture electron microscopy

• Nuclear magnetic resonance

• Fluorescence microscopy