In eukaryotes, ribosomes become associated with endoplasmic reticulum membranes when a signal sequence

In eukaryotes, ribosomes become associated with endoplasmic reticulum membranes when a signal sequence from the RNA is given. In the cytoplasm, ribsomal RNA (rRNA), a type of RNA, and protein combine to form a nucleoprotein called a ribosome. The ribosome serves as the site and carries the enzymes necessary for protein synthesis. They are often takes the shape of small round particles attached in the endoplasmic reticulum. The ribosome attaches itself to m-RNA and provides the stabilizing structure to hold all substances in position as the protein is synthesized. An example of a eukaryote is the protists. Protists belong to the group eukaryotes (having their DNA enclosed inside the nucleus). They are not plants, animals or fungi but they act like one. They can be in general subgroups such as unicellular algae, protozoa and molds. They thrive in environments with little sunlight. 

Gravitational force i believe