Evolution of photosynthesis symbiotic relationship with chloroplasts they capture from the algae in their diet and then store in their bodies. This allows the mollusks to survive solely by photosynthesis for several months at a time. Some of the genes from the plant cell nucleus have even been transferred to the slugs, so that the chloroplasts can be supplied with proteins that they need to survive. An even closer form of symbiosis may explain the origin of chloroplasts. Chloroplasts have many similarities with photosynthetic bacteria, including a circular chromosome, prokaryotic-type ribosomes, and similar proteins in the photosynthetic reaction center. The endosymbiotic theory suggests
Granule cell fibers form thousands of excitatory Granule-cell-Purkinje-cell synapses onto the dendrites of Purkinje cells. This connection is excitatory as glutamate is released. The parallel fibers and ascending axon synapses from the same granule cell fire in synchrony which results in excitatory signals. In the cerebellar cortex there are a variety of inhibitory neurons (interneurons). The only excitatory neurons present in the cerebellar cortex are granule cells. Plasticity of the synapse between a parallel fiber and a Purkinje cell is believed to be important for motor learning. The function of cerebellar circuits is entirely dependent on processes carried out by the granular