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
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
Fluid nature of plasma membrane helps in all, except
Cell growth and division
Formation of intercellular junctions
Endocytosis and exocytosis
Providing mechanical strength
Most common type of lipids found in plasma membrane is A and they show B__ movement with in the plasma membrane. Choose the most appropriate option to fill A and B.
Phospholipids; Lateral
Glycolipids; Transverse
Cholesterol; Rotational
Steroids; Flip-flop
The fluidity of membranes in a plant in cold weather may be maintained by
Increasing the number of phospholipids with unsaturated hydrocarbon tails
Increasing the proportion of integral proteins
Increasing concentration of cholesterol in membrane
Increasing the number of phospholipids with saturated hydrocarbon tail
Select the incorrect statement about plasma membrane
It is selectively permeable.
It is composed of a phospholipid bilayer.
It contains proteins.
It is primarily composed of carbohydrates.
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
Fluid nature of plasma membrane helps in all, except
Formation of intercellular junction
Cell growth and cell division
Lateral movement of proteins within the overall lipid bilayer
Active transport through ion channels
Select the incorrect statement about plasma membrane
It is selectively permeable.
It is composed of a phospholipid bilayer.
It contains cholesterol in animal cells.
It is a static structure.
RNA is not found in
Chromosome
Plasmalemma
Nucleolus
Ribosome
