The evolution of photosynthesis and chloroplasts
- Molecular Cell Biology
evolution of photosynthesis in the past five years, and
omits evolution of CO2 assimilation. Oxygenic photosynthesis
(using both photosystems I and II) has evolved
from anoxygenic photosynthesis. The latter occurs in
different variants, using either a type 1 photosystem
resembling photosystem I, or a type 2 photosystem resembling
photosystem II. Opinions differ as to how
two types of photosystem came to be combined in the
same organism, whether by gene transfer between bacteria,
by fusion of bacteria, or as a result of gene duplication
and evolution within one kind of bacterium.
There are also different opinions about when oxygenic
photosynthesis arose, in conjunction with the Great
Oxygenation Event, 2.3 billion years before the present,
or more than a billion years before that.
Cyanobacteria were the first organisms to carry out
oxygenic photosynthesis. Some of them gave rise to
chloroplasts, while others continued to evolve as independent
organisms, and the review outlines both lines
of evolution. At the end we consider the evolution of
photosynthesis in relation to the evolution of our planet.
- Biological Sciences
- horizontal gene transfer
- red algae.
- ISSN: 0011-3891