Nerve impulses are transmitted across neurons through the release of neurotransmitter molecules. The neurotransmitter molecules diffuse across the space between the neurons (synapse) and bind to neurotransmitter receptors that in turn. Neurons are often pre-labeled with lipophilic dyes to visualize all of their processes. The structure for one such dye, Dil is shown below. These dyes are specifically introduced to very small regions of a cells membrane, however the dye will eventually diffuse to label the entire plasma membrane. a) Given Dil\'s chemical properties and the features of the plasma membrane, explain this why the dye is \"lipophilic\" and why it will diffuse to label the entire plasma membrane. b) Given an infinite amount of time, Dil fluorescence is never observed in the cytosol of a Dil labeled cell. Explain. Solution a> It has fluroscent properties and can be dissolve in fats, lipids, oils etc so that it usally incorporated into plasma membrane which is made up of lipid bilayer easily by the lateral diffusion process. b> It can only stains the plasma membrane of neurons and used to detect the optical property and fludity of membrane as it is known as a retrograde, carbocyanine, lipophilic membrane stain. As cytosol contains water, disslved ions as well as small and large water soluble components so the Dil fluroscence dye cannot dissolved in cytosol..

1. Nerve impulses are transmitted across neurons through the release of neurotransmitter
molecules. The neurotransmitter molecules diffuse across the space between the neurons
(synapse) and bind to neurotransmitter receptors that in turn. Neurons are often pre-labeled with
lipophilic dyes to visualize all of their processes. The structure for one such dye, Dil is shown
below. These dyes are specifically introduced to very small regions of a cells membrane,
however the dye will eventually diffuse to label the entire plasma membrane. a) Given Dil's
chemical properties and the features of the plasma membrane, explain this why the dye is
"lipophilic" and why it will diffuse to label the entire plasma membrane. b) Given an infinite
amount of time, Dil fluorescence is never observed in the cytosol of a Dil labeled cell. Explain.
Solution
a> It has fluroscent properties and can be dissolve in fats, lipids, oils etc so that it usally
incorporated into plasma membrane which is made up of lipid bilayer easily by the lateral
diffusion process.
b> It can only stains the plasma membrane of neurons and used to detect the optical property and
fludity of membrane as it is known as a retrograde, carbocyanine, lipophilic membrane stain. As
cytosol contains water, disslved ions as well as small and large water soluble components so the
Dil fluroscence dye cannot dissolved in cytosol.