Endosymbiosis and the origins and diversification of complex multicellular life

What are the two main categories of cells in life?

Single celled and multicellular organisms.

What is one key difference in the cell size between single-celled and multicellular organisms?

Single-celled organisms are typically small (1-10 microns), while multicellular organisms are larger (10-100 microns).

What significant structures do eukaryotic cells possess that prokaryotic cells do not?

Eukaryotic cells have a nucleus and membrane-bound organelles.

What is the theory of endosymbiosis?

The theory that mitochondria originated from a symbiotic relationship when a larger archaea cell engulfed a smaller aerobic bacteria.

What evidence supports the endosymbiotic origin of mitochondria?

Mitochondria have their own circular DNA, replicate by fission, and have ribosomes similar to bacterial ribosomes.

What is horizontal gene transfer (HGT)?

The transfer of genetic information between organisms, which can occur via transformation, transduction, or conjugation.

What are chloroplasts thought to have originated from?

Chloroplasts are believed to have originated when a protist engulfed a cyanobacterium.

How do cyanobacteria impact the Earth's atmosphere?

Cyanobacteria can photosynthesize, producing oxygen and changing the atmospheric composition.

What is a key point of multicellularity?

Not all cells express the same genes; cellular specialization occurs.

What common characteristics are found in complex multicellular organisms?

Clonal development, sophisticated cell adhesion mechanisms, specialized communication pathways, and tissue differentiation.

What are the general requirements for multicellular life?

Cells must stick together, communicate/interact, and have a genetic program to guide growth and development.

What role do Hox genes play in multicellular organisms?

Hox genes guide the development and differentiation of tissues in multicellular organisms.