Question

Name one or more membrane activities that occur both in fertilization of an egg and in neurotransmission across a synapse (see Figure 47.3).

Short answer

The fertilization and neural transmission process are entirely different, yet some of the steps are common to them. The mechanism of membrane depolarization, along with membrane fusion and exocytosis, occurs in both physiological processes.

Step-by-step solution

Neurotransmission

The mechanism through which neurons conduct messages from one region of the body to another is denoted as neurotransmission. This process occurs at the synapse, where the signal from a presynaptic nerve cell is conducted forward to another nerve cell or target tissues (regarded as the postsynaptic nerve or end).

The molecules of neurotransmitters are used for conducting the signals from the presynaptic end to the synapse’s postsynaptic end.

Step 2:Fertilization

The physiological process which accounts for the continuation of life via the sexual mode of reproduction is denoted as fertilization. In this process, male gametic cells fuse with the female gametic cell, and this union of haploid cells results in the formation of a diploid cell (zygote).

Similar processes in fertilization and neurotransmission

In neurotransmission, the signal received at the presynaptic end depolarizes the presynaptic neuron’s membrane.This increases the calcium influx, which leads to the fusion of the synaptic vesicle’s membrane with the neuron’s membrane. After this, the neurotransmitters are released via exocytosis.

Fertilization also includes the steps of exocytosis, membrane depolarization, and membrane fusion.

At first, the hydrolytic enzymes released by the sperm cause exocytosis of the egg’s jelly coat. It is followed by the protrusion of the acrosome process and its binding with the egg membrane’s receptors.This causes depolarization of the egg membrane and prevents another sperm’s entry.

After this, the plasma membrane of both the gametic cells fuse, followed by the transfer of the sperm’s genome within the egg cell. This accounts for the fertilization of the egg.