Cell Membrane Dynamics: Exocytosis, Endocytosis, and Vesicle Transport in Biology

What is exocytosis?

The process by which materials are secreted from cells.

What is endocytosis?

The process by which materials are taken into the cell.

What is phagocytosis?

A type of endocytosis where large particles are engulfed by the cell.

What is pinocytosis?

A type of endocytosis where the cell ingests extracellular fluid and dissolved solutes.

What is receptor-mediated endocytosis (RME)?

A process where cells take in specific molecules based on a receptor-ligand interaction.

What role do lysosomal enzymes play in endocytosis?

They await the arrival of materials for digestion after endocytosis.

What is autophagy?

The process by which damaged organelles are degraded and recycled within the cell.

What are the three main events that must occur at the plasma membrane for insulin secretion?

Tethering, docking, and fusion of the vesicle with the plasma membrane.

What proteins are involved in the tethering process during vesicle secretion?

Rab proteins and protein tethers.

What is the function of V-SNARE and T-SNARE proteins?

They facilitate the docking of vesicles to the target membrane.

What triggers the fusion of vesicles with the plasma membrane?

Calcium ion (Ca2+) influx.

What is tetanus and what causes it?

A life-threatening disease caused by the tetanus toxin produced by Clostridium tetani.

How does tetanus toxin affect neurotransmitter release?

It cleaves v-SNARE synaptobrevin, preventing the release of the inhibitory neurotransmitter GABA.

What is the result of GABA inhibition being blocked in tetanus?

Continuous stimulation by excitatory neurotransmitters leads to spastic paralysis.

What is botulism and what causes it?

A bacterial poisoning caused by botulinum toxin produced by Clostridium botulinum.

How does botulinum toxin affect muscle contraction?

It cleaves t-SNARE SNAP25, preventing acetylcholine vesicle docking and leading to flaccid paralysis.

What are some uses of botulinum toxin in medicine?

It is used to prevent wrinkles, muscle spasms, hyperhidrosis, and migraines.

What is the role of the Golgi apparatus in the secretory pathway?

It processes and packages proteins for secretion from the cell.

What happens to insulin in the secretory pathway?

It is bound by the Hypothetical Insulin Binding Receptor A23 and packaged into vesicles for secretion.

What is the significance of clathrin proteins in vesicle formation?

They are involved in the formation of vesicles during endocytosis and secretion.

What is the function of adaptor proteins in vesicle transport?

They help in the recruitment and assembly of clathrin and other proteins for vesicle formation.