![This is blank.](https://digitalhistology.org/wp-content/themes/histology-unified/imgs/trans.png)
Rough endoplasmic reticulum and polysomes
This electron micrograph shows a cell with RER and many polysomes, or polyribosomes. Polysomes are groups of ribosomes attached to a single messenger RNA molecule that synthesize protein for internal use by the cell. 30,000x
![Ribosomes on RER <p>This electron micrograph shows a cell with RER and many polysomes, or polyribosomes. Polysomes are groups of ribosomes attached to a single messenger RNA molecule that synthesize protein for internal use by the cell. 30,000x</p>](https://digitalhistology.org/wp-content/uploads/2017/05/C.S.ER-9-2-ping.png)
Ribosomes on RER
This electron micrograph shows a cell with RER and many polysomes, or polyribosomes. Polysomes are groups of ribosomes attached to a single messenger RNA molecule that synthesize protein for internal use by the cell. 30,000x
![Polysomes > <p>Each polyribosome contains a single mRNA molecule being translated by many ribosomes. For some proteins, e.g., cytoskeletal and metabolic proteins, translation occurs in the cytoplasm. For others, such as secreted proteins or membrane spanning proteins, translation is temporarily halted while the polyribosome is translocated to the ER where translation continues. The signal for where translation occurs is contained in the leader sequence of the mRNA.</p>](https://digitalhistology.org/wp-content/uploads/2017/05/C.S.ER-9-1-ping.png)
Polysomes >
Each polyribosome contains a single mRNA molecule being translated by many ribosomes. For some proteins, e.g., cytoskeletal and metabolic proteins, translation occurs in the cytoplasm. For others, such as secreted proteins or membrane spanning proteins, translation is temporarily halted while the polyribosome is translocated to the ER where translation continues. The signal for where translation occurs is contained in the leader sequence of the mRNA.
![Nucleus <p>This electron micrograph shows a cell with RER and many polysomes, or polyribosomes. Polysomes are groups of ribosomes attached to a single messenger RNA molecule that synthesize protein for internal use by the cell. 30,000x</p>](https://digitalhistology.org/wp-content/uploads/2017/05/C.S.ER-9-3-ping.png)
Nucleus
This electron micrograph shows a cell with RER and many polysomes, or polyribosomes. Polysomes are groups of ribosomes attached to a single messenger RNA molecule that synthesize protein for internal use by the cell. 30,000x
![Plasma membrane <p>This electron micrograph shows a cell with RER and many polysomes, or polyribosomes. Polysomes are groups of ribosomes attached to a single messenger RNA molecule that synthesize protein for internal use by the cell. 30,000x</p>](https://digitalhistology.org/wp-content/uploads/2017/05/C.S.ER-9-4-ping.png)
Plasma membrane
This electron micrograph shows a cell with RER and many polysomes, or polyribosomes. Polysomes are groups of ribosomes attached to a single messenger RNA molecule that synthesize protein for internal use by the cell. 30,000x
![Intercellular space <p>This electron micrograph shows a cell with RER and many polysomes, or polyribosomes. Polysomes are groups of ribosomes attached to a single messenger RNA molecule that synthesize protein for internal use by the cell. 30,000x</p>](https://digitalhistology.org/wp-content/uploads/2017/05/C.S.ER-9-5-ping.png)
Intercellular space
This electron micrograph shows a cell with RER and many polysomes, or polyribosomes. Polysomes are groups of ribosomes attached to a single messenger RNA molecule that synthesize protein for internal use by the cell. 30,000x