Notesale: Turn your study into money

Document Preview

Extracts from the notes are below, to see the PDF you'll receive please use the links above

---

The endosymbiotic theory
symbiosis is a close relationship between two different organisms therefore endosymbiosis
looks at the close relationship between cells
...
In the 1960s she studied the
structure of cells ,and found that the mitochondria looked like bacteria
...
Thus scientists became convinced that
chloroplasts , like mitochondria evolved from symbiotic bacteria - specifically that they
descended from cyanoabacteria, the light harnessing small organisms that abound in
oceans and fresh water
...
The chloroplast with which plants make food for themselves is actually a
cyanobacterium living within the plant's cells
...
This event is known as
endosymbiosis, and is also the origin of the eukaryotic mitochondrion
...

Therefore when one of Margulis’ professors found DNA inside chloroplasts , she was not
surprised and in 1970 she published her argument in ‘The Origin Of Eukaryotic Cells’
...
This came about when a host cell
(eukaryotic) first engulfed the respiration prokaryote cell and photosynthetic prokaryote
cell, thus becoming endosymbionts and forming a mutually beneficial relationship
...
mitochondria originated from free-living
oxygen-metabolizing (aerobic) bacteria that were engulfed by an ancestral eukaryotic cell
that did not make use of oxygen
...
The ingested cell would continue to provide glucose
and oxygen (which could be used by the mitochondria as endocytosis of the
photosynthetic prokaryote occurred after the endocytosis of aerobic cells) by
photosynthesis
...
The inner
membrane of these organelles contains enzymes and transport systems that are similar to
the plasma membrane of prokaryotes
...
They discovered
that the chloroplasts genes bore little resemblance to the genes in the algae’s
nuclei
...
The DNA in
mitochondria resembles that within a group of bacteria that includes the type of bacteria
that causes typhus - (an illness caused by infection with rickestssia bacteria
...
Thus this enables mitochondria
and chloroplasts to replicate independently of their host cells
...




---