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 membrane in animals is composed mainly of the molecules of?
phospholipids
carbohydrates
nucleic acids
proteins
Which component of the cell membrane is primarily responsible for its selective permeability?
Glycoproteins
Peripheral proteins
Phospholipid bilayer
Cholesterol
Lipid bilayer is present in
Plasma membrane
Ribosome
Chromosome
Nucleolus
Fluid mosaic model was given by
Beadle and Tatum
Jacob and Monod
Singer and Nicolson
Watson and Crick
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
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 cell membrane is best described as:
Fully permeable
Impermeable
Selectively permeable
Rigid and unchanging
I. It is the extension of plasma membrane into the cytoplasm
II. It helps in cell wall formation, DNA replication, respiration, secretion processes, increases the surface area of plasma membrane and enzymatic contents. It also helps in cytokinesis
III. It I the characteristic of bacterial cells
The above features are attributed to bacteria
Mesosomes
Ribosomes
Nucleoid
Plasmids
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
Which of the following is NOT a primary function of cell membrane proteins?
Transporting molecules across the membrane
Acting as receptors for signaling molecules
Synthesizing lipids
Providing structural support to the membrane
