Endosymbiotic Theory

What does “endo-” mean?

inside

What does “symbiotic” mean?

living together

Symbiosis involves ____ __________ ______ living together

2 separate species

What came first? Prokaryotes or eukaryotes?

Prokaryotes

Mitochondria and chloroplast lived as…

free living bacteria

How did membrane bound organelles come to be?

In some large prokaryotes, the cell membrane folded inward to make “pockets” inside the cell.

What happened to the cells that didn’t fold inward?

Remained prokaryotes

How was the nucleus formed?

Infolded cell membrane surrounded the cell’s DNA

When was the start of infolding of cell membrane to make the nucleus (estimate)?

About 2.5 billion years ago

How were mitochondria created?

Some primitive eukaryotes engulfed a small energy producing prokaryote

After mitochondria were created, _______ _____ were created

animal cells

How were chloroplast created?

Some ancient animal cells engulfed a small photosynthetic prokaryote

After chloroplast were created, ________ _____ were created

plant cells

What is the evidence of endosymbiotic theory?

• Both the mitochondria and chloroplast are roughly the same size as prokaryotic cells

• Have double membranes

• Have their own DNA and ribosomes

• Are autonomous

Why is it significant that both mitochondria and chloroplast have double membranes?

• Because their own original membranes consist of molecules that are more “prokaryotic” in structure

• The newer membrane is gained from being engulfed, wish consists of molecules that are more “eukaryotic” in structure

Why is it significant that both mitochondria and chloroplast have their own DNA and ribosomes?

• Their DNA are more circular, similar to prokaryotic cells’ DNA

• Their ribosomes have the same size and structure as prokaryotic ribosomes

What does it mean for the mitochondria and chloroplast to be autonomous?

They grow and divide on their own—separate from the rest of the cell, similar to bacteria

Why is endosymbiotic theory in this specific order? (bacteria cell + mitochondria = animal cell + chloroplast = plant cell)

Animals only have one mitochondria, whereas plant cells have mitochondria and chloroplast; Cells are more likely to gain 1 organelle then another than to gain 2 then lose 1

What is The Endosymbiotic Theory order?

Bacteria cell + mitochondria → animal cell; animal cell + chloroplast → plant cell

Cells are more likely to _____ ___ organelle then another than to _______ ____ then _____ ____

gain 1; gain 2; lose 1

Mitochondria multiply by _______ in _____

pinching; half

What reproduction process is similar to mitochondria’s?

bacteria

Every new mitochondrion must be produced from a _______ mitochondrion

parent

If a cell’s mitochondria are removed, can it build new ones from scratch?

No