Origin of the Eukaryotic Endomembrane System / Trends in Microbiology July 2016 (Vol. 24 Issue 7)

Summary

The video discusses the evolution of eukaryotic cells, focusing on the endomembrane system and its origins. It suggests that this system may have evolved from the mitochondria through the secretion of outer membrane vesicles (OMVs). By proposing that ancestral mitochondria produced OMVs during endosymbiosis, the video highlights how these vesicles could have initiated the development of the eukaryotic endomembrane system. The model emphasizes the significance of endosymbiosis in enhancing eukaryotic complexity, with the nuclear envelope evolving to facilitate distinct transcription and translation processes. Overall, it offers a fresh perspective on the emergence of eukaryotic cellular structures.

Takeaways

• 🧬 Eukaryotic cells are distinguished from prokaryotic cells primarily by the eukaryotic endomembrane system.
• 🔍 The origin of the endomembrane system is unclear, as no true intermediates in the transition from prokaryotes to eukaryotes have been identified.
• 🌍 The prokaryotic to eukaryotic transition is considered a significant evolutionary divide in the history of life.
• 🧫 Many models suggest that the endomembrane system evolved from inward invaginations of the plasma membrane.
• 📦 Endocytosis and phagocytosis are often viewed as prerequisites for the development of the eukaryotic endomembrane system.
• 🔄 Current genetic studies indicate that mitochondria evolved through endosymbiosis with a bacterial ancestor.
• 💡 The proposed model suggests that the eukaryotic endomembrane system originated from the mitochondrion via outer membrane vesicles (OMVs).
• 🌊 It has been known for decades that prokaryotes can secrete vesicles into their environment.
• 📈 The ancestral mitochondrion is believed to have produced OMVs, which contributed to the initial formation of the eukaryotic endomembrane system.
• 🔗 The sequence of events in the development of eukaryotic cell compartments starts with the endoplasmic reticulum (ER), followed by the nucleus and phagocytosis.

Q & A

What distinguishes eukaryotic cells from prokaryotic cells?

One of the most significant distinctions is the presence of the eukaryotic endomembrane system.

What is the origin of the eukaryotic endomembrane system?

Its origin is puzzling because no true intermediates in the prokaryotic to eukaryotic transition are known at the level of cell organization.

What has been proposed about the transition from prokaryotes to eukaryotes?

Many models suggest that the endomembrane system derived from inward invaginations of the plasma membrane.

What role does phagocytosis play in the eukaryotic endomembrane system?

Phagocytosis is considered a prerequisite for the uptake of symbionts in the theories about the eukaryotic endomembrane system.

How does current genetic research impact our understanding of mitochondria's origin?

Current genetic studies indicate that mitochondria arose in an ancestral host through endosymbiosis and were present in the common ancestor of eukaryotes.

What is the new proposal regarding the origin of the eukaryotic endomembrane system?

The proposal suggests that the eukaryotic endomembrane system originated from the mitochondrion in the form of outer membrane vesicles (OMVs).

How do modern mitochondria contribute to the endomembrane system?

Modern mitochondria generate membrane vesicles that they secrete into the cytoplasm, which can provide a foundational structure for the endomembrane system.

What occurs when mitochondrial vesicles fuse with each other?

Fusion of mitochondrial vesicles yields a basic endomembrane system, allowing for natural variation and selection.

What is the role of the nuclear envelope in relation to transcription and translation?

The nuclear envelope evolved to separate transcription, which occurs in the nucleus, from translation, which occurs in the cytoplasm.

What is the sequence of events leading to the formation of eukaryotic cell compartments?

The sequence begins with the endoplasmic reticulum (ER), followed by the co-translational secretion system, leading to the formation of the nucleus and inward membrane flux through phagocytosis.