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
Cell adhesion and cell recognition occur due to biochemicals of cell membrane named
Lipids
Proteins
Glycoproteins and glycolipids
Both (a) and (b)
The plasma membrane consists mainly of
Phospholipids embedded in a protein bilayer
Proteins embedded in a phospholipid bilayer
Proteins embedded in a polymer of glucose molecules
Proteins embedded in a carbohydrate bilayer
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
Fluid mosaic model was given by
Beadle and Tatum
Jacob and Monod
Singer and Nicolson
Watson and Crick
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
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
What is the function of cholesterol in the cell membrane?
Provide structural support
Transport molecules
Maintain fluidity
Act as receptors
Which part of the phospholipid is hydrophobic?
Phosphate head
Glycerol backbone
Fatty acid tails
Entire molecule
Which of the following is the primary component of the cell membrane?
Carbohydrates
Proteins
Nucleic acids
Phospholipids
Which type of molecule can easily pass through the cell membrane without assistance?
Large, polar molecules
Ions
Small, nonpolar molecules
Proteins
