A researcher is studying the transport of a novel molecule across a synthetic lipid bilayer. They observe that the molecule moves down its concentration gradient without the need for any membrane proteins or energy input. However, the rate of transport is significantly slower than predicted for simple diffusion. Which of the following BEST explains this observation?
The molecule is very large and its size restricts diffusion through the membrane.
The molecule is charged and is repelled by the hydrophobic core of the bilayer.
The molecule is polar and its passage is hindered by the hydrophobic core of the bilayer.
The molecule is binding to a specific receptor on the membrane surface, slowing its diffusion.
Related Questions
According to Singer and Nicolson model of cell membrane
The quasi-fluid nature of lipid enables lateral movement of protein within over all bilayer
The quasi-fluid nature of protein enables lateral movement of lipid
Peripheral proteins are totally buried in the phospholipid bilayer
Tunnel proteins lie on the surface of cell membrane
In fluid mosaic model of plasma membrane
Upper layer is non-polar and hydrophilic
Polar layer is hydrophobic
Phospholipids form a bimolecular layer in middle part
Proteins from a middle layer
A widely accepted, improved model of cell membrane is
Fluid mosaic model
Robertson’s model
Danielli and Davson’s mod
Unit membrane model
Keeping in view the ‘fluid mosaic model’ for the structure of cell membrane, which one of the following statement is correct with respect to the movement of lipids and proteins from one lipid monolayer to the other (described as flip-flop movement)?
Both lipids and proteins can flip-flop
While lipids can rarely flip-flop, proteins cannot
While proteins can flip-flop, lipids cannot
Neither lipids nor proteins can flip-flop
Fluid mosaic model was given by
Beadle and Tatum
Jacob and Monod
Singer and Nicolson
Watson and Crick
A widely accepted, improved model of cell membrane is
Fluid mosaic model
Robertson’s model
Danielli and Davson’s mod
Unit membrane model
Keeping in view the ‘fluid mosaic model’ for the structure of cell membrane, which one of the following statement is correct with respect to the movement of lipids and proteins from one lipid monolayer to the other (described as flip-flop movement)?
Both lipids and proteins can flip-flop
While lipids can rarely flip-flop, proteins cannot
While proteins can flip-flop, lipids cannot
Neither lipids nor proteins can flip-flop
According to widely accepted ‘fluid mosaic model’ cell membranes are semi-fluid, where lipids and integral proteins can diffuse randomly. In recent years, this model has been modified in several respects. In this regard, which of the following statement is incorrect?
Proteins in cell membranes can travel within the lipid bilayer
Proteins can remain confined within certain domains of the membrane
Proteins can also undergo flip-flip movements in the lipid bilayer
Many proteins remain completely embedded within the lipid bilayer
The fluid mosaic model describes the cell membrane as:
A rigid, static layer
A solid barrier
A dynamic structure with embedded proteins
A single layer of phospholipids
Fluid nature of plasma membrane helps in all, except
Cell growth and division
Formation of intercellular junctions
Endocytosis and exocytosis
Providing mechanical strength
