Fluorescent FM dyes partition reversibly into biological membranes without penetrating through them. Suppose that you have neurons cultured in a dish, and you incubate them with an FM dye for a period of time before washing the cells with excess medium to remove the dye. a)You find that if you stimulate the neurons to trigger action potentials during incubation with the dye, the synaptic regions of the neurons remain fluorescent after the wash. Propose an explanation for this effect. b)After you have generated fluorescent synaptic regions by this procedure, suppose that you trigger further action potentials while continuing to wash with excess medium. Would you expect the synaptic regions to lose fluorescence

a) Emission observed is due to emission of synaptic vessels

b) Yes

Explanation:

a) Proposing an explanation

The emission observed ( the synaptic regions of the neurons remaining fluorescent ) is due to the emission on the synaptic vessels given that FM dyes have lipid-sensitive emission which can be loaded into a recycled synaptic vesicle

b)

The synaptic regions will lose fluorescence when you continue to wash with excess medium, also the more action potentials triggered the more observed emission. hence the increase in the loss of fluorescence is due to the fact that the emissions are not permanent

step 1: initiation

initiation is the beginning of transcription. it occurs when the enzyme rna polymerase binds to a region of a gene called the promoter. this signals the dna to unwind so the enzyme can ‘‘read’’ the bases in one of the dna strands. the enzyme is now ready to make a strand of mrna with a complementary sequence of bases.

step 2: elongation

elongation is the addition of nucleotides to the mrna strand. rna polymerase reads the unwound dna strand and builds the mrna molecule, using complementary base pairs. there is a brief time during this process when the newly formed rna is bound to the unwound dna. during this process, an adenine (a) in the dna binds to an uracil (u) in the rna.

step 3: termination

termination is the ending of transcription, and occurs when rna polymerase crosses a stop (termination) sequence in the gene. the mrna strand is complete, and it detaches from dna.