🧬 Eukaryotic Formation

• Infolding

Process forming internal membranes like the ER and nuclear envelope.

• Endosymbiosis

Theory that mitochondria and plastids originated from engulfed prokaryotes.

• Endomembrane System

Includes ER, Golgi apparatus, and nuclear envelope; formed via membrane infolding.

• Organelles via Infolding

ER, nuclear envelope, Golgi.

• Organelles via Endosymbiosis

Mitochondria and chloroplasts.

• Ribosome Attachment to ER

Occurs via signal sequences during protein synthesis.

• Organelle Formation Order

Nucleus → Mitochondria → Chloroplasts.

• Cytoskeleton

Network of protein filaments for cell shape and transport.

• Centriole

Structure involved in cell division in animal cells.

• Nucleus

Membrane-bound organelle housing DNA.

- Enfolding

The inward folding of the plasma membrane in ancestral prokaryotes, leading to the formation of internal structures like the nuclear envelope and endoplasmic reticulum.

- Primary Endosymbiosis

A symbiotic event where a eukaryotic ancestor engulfed a prokaryote (e.g., an aerobic bacterium or cyanobacterium), giving rise to mitochondria and plastids.

- Structures from Enfolding

Nuclear envelope, endoplasmic reticulum, Golgi apparatus.

- Structures from Endosymbiosis

Mitochondria (from aerobic bacteria), chloroplasts (from cyanobacteria).

- Plastids

Organelles involved in photosynthesis and storage in plant and algal cells.

- Examples of Plastids

Chloroplasts, chromoplasts, leucoplasts.

- Endosymbiotic Theory Evidence

Mitochondria and plastids have double membranes, circular DNA, prokaryote-like ribosomes, and replicate independently via binary fission.

- Mitochondria Origin

Derived from engulfed aerobic proteobacteria.

- Chloroplast Origin

Derived from engulfed cyanobacteria.

- Eukaryotic Tree Relationships

Eukaryotes are divided into supergroups (e.g., Archaeplastida, SAR, Excavata, Unikonta) that include protists and multicellular lineages like plants, animals, and fungi.

- Protists comparison to Plants

Green algae (protists) are ancestors of land plants within Archaeplastida.

- Protists comparison to Animals/Fungi

Choanoflagellates (protists) are closely related to animals; fungi and animals share a common ancestor in Unikonta.

- Supergroups

Major evolutionary branches of eukaryotes that include both protists and multicellular organisms.