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EndosymbiosisVenkatesh Rao

IB Year 1A

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Contents

Introductory Video

What is endosymbiosis?

Animated Representation

The Process ExplainedWhat is the Biological Reasoning?

History of Endosymbiosis

Endosymbiotic Gene Transfer

The Evidence

Secondary Endosymbiosis

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Introductory Video

http://www.youtube.com/watch?v=-FQmAnmLZtE

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So, what is endosymbiosis?

This theory states that several organelles in eukaryotic cells originated a

relationships between single-celled prokaryotic organisms.These organelles include mitochondria and chloroplasts among many

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Animated Representation

http://www.youtube.com/watch?v=3ESXvLHceDc

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"Serial endosymbiosis" by Kelvinsong - Own work. Licensed under Creative Commons Attribution-Share Alike 3.0 via Wikimedia Commons -http://commons.wikimedia.org/wiki/File:Serial_endosymbiosis.svg#mediaviewer/File:Serial_endosymbiosis.svg

"Endosymbiosis". Licensed under Creative Commons Attribution-Sharehttp://commons.wikimedia.org/wiki/File:Endosymbiosis.PNG#mediav

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A little about the theorys history

First thought of in 1910 by Russian botanist Konstantin Mereschkow

The theory was initially dismissed

The theory was advanced by Lynn Margulis in 1967

Life did not take over the globe by combat, but by networking[2]

[1] Martin, William; Mayo Roettger, Thorsten Kloesges, Thorsten Thiergart, Christian Woehle, Sven Gould and Tal Dagan. "Modern endosymbiotic theory: Getting lateral gene transfer in-toof Endocytobiosis and Cell Research23: 15.

[2] Lynn Sagan (1967). "On the origin of mitosing cells".J Theor Biol14(3): 255274. doi:10.1016/0022-5193(67)90079-3. PMID 11541392.

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Endosymbiotic Gene Transfer

Some genes from the endosymbionts were transferred to the nucleushost cell (which may have been a prokaryotic cell)

This is seen as the main move from a symbiotic community to a fullyinstituted eukaryotic cell

Some DNA (in the form of plasmids) however, was left behind in thendosymbionts (to form the organelles of eukaryotic cells)

This was tested by studying the number of genomes in a bacterial cethe number in organelles.

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The Evidence

New mitochondria and chloroplasts are formed by a process similar to binary

If the mitochondria or chloroplasts of a cell are destroyed they will not regen

Transport proteins are found in the membranes of several organelles (to tran

The membrane lipid Cardiolipin, and several specific genesarefound exclusive

inner mitochondrial membrane and the cell membrane of the bacteria Rickett

Mitochondria and chloroplasts contain plasmids which are similar to those in

Mitochondria have several enzymes and transport systems similar to those of

These organelles' ribosomes are like those found in bacteria (70S)

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Secondary Endosymbiosis

This occurs when the product of a primary endosymbiosis is itself enand retained by another free living eukaryotic cell. This process has le

formation of many diverse types of algae and other eukaryotic spe

http://endosymbiotichypothesis.files.wordpress.com/2010/09/pacman-copy.gif https://reader003.{domain}/reader003/html

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