Why do ribosomes attach to the endoplasmic reticulum?

Ribosomes are known to be the protein synthesizer of the cell and the attachment of the ribosomes to the membrane of the endoplasmic reticulum is to make it rough endoplasmic reticulum. However, the process of protein synthesis usually starts when mRNA moves from the nucleus to ribosomes on the surface of the rough endoplasmic reticulum.

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step 1: nitrogen fixation- conversion of atmospheric no₂ into forms useful to plants by lightning, bacteria, and cyanobacteria.

step 2: nitrification-process of converting ammonia to nitrite or nitrate.

step 3: assimilation-plant roots absorb new form of nitrogen.

step 4: ammonification-conversion of organic nitrogen to ammonia by bacteria involved in decomposition.

step 5: denitrification-bacteria turns the decomposed matter back into n₂o, which is released into atmosphere; repeat cycle.