A2.2.12 Origin of eukaryotic cells by endosymbiosis (HL) | Quizlet

What is the key concept that explains the origin of mitochondria and chloroplasts?

Endosymbiosis.

What is the definition of endosymbiosis?

One organism living inside another in a mutually beneficial relationship.

What advantage did the common ancestor of eukaryotes have over prokaryotes?

It could protect its genetic material and enable sexual reproduction.

What is the first step of endosymbiosis?

Engulfment: A larger host cell engulfs a smaller prokaryote.

What happened to the engulfed prokaryote in the endosymbiotic process?

It became a permanent resident and evolved into an organelle.

What is the mutual benefit in the endosymbiotic relationship?

The prokaryote provides energy through respiration, while the host cell provides protection.

How did the engulfed prokaryote lose its independence?

Over time, it became a fully integrated organelle within the host cell.

What is one example of photosynthetic endosymbiosis?

A eukaryotic cell engulfing a photosynthetic prokaryote, which evolved into chloroplasts.

Name one piece of evidence supporting the endosymbiotic theory.

Mitochondria and chloroplasts contain 70S ribosomes, like those in prokaryotes.

What does the 'S' in 70S ribosomes refer to?

Svedberg units, a measure of how quickly ribosomes settle during centrifugation.

What type of DNA do mitochondria and chloroplasts have?

Naked, circular DNA similar to prokaryotic DNA.

How do mitochondria and chloroplasts replicate?

They replicate independently, resembling binary fission in bacteria.

What is a common misconception about the replication of mitochondria and chloroplasts?

That they are produced by the cell's nucleus, when they are actually self-replicating.

What type of membrane do mitochondria and chloroplasts have?

A double membrane.

Why is the double membrane significant?

The inner membrane resembles the engulfed prokaryote's membrane.

Can mitochondria and chloroplasts arise by division of pre-existing organelles?

Yes, this is a prediction of the endosymbiotic theory that has been confirmed.

How can understanding mitochondrial DNA be applied medically?

It helps in studying mitochondrial diseases.

What is one area of biotechnology that explores endosymbiosis?

Synthetic organelles and energy-efficient cell engineering.

Why is the endosymbiotic theory considered robust?

It explains a wide range of observations and predictions have been confirmed through evidence.

What shared features between mitochondria/chloroplasts and prokaryotes does the theory predict?

70S ribosomes and circular DNA.

What role did cooperation play in the evolution of eukaryotic cells?

Cooperation through symbiotic partnerships led to the development of complex eukaryotic cells.