protein synthesis

• 1. the gene that has the coded instructions for a protein such as insulin, housed on chromatin in the nucleus, is transcribed into a length of RNA called messenger RNA (mRNA)
• 2. many copies of this mRNA are made and they pass out of the pores in the nuclear envelope to the ribosomes
• 3. at the ribosomes, the instructions are translated and insulin molecules are assembled
• 4. the insulin molecules pass into the cisternae of the rough endoplasmic reticulum and along these hollow sacs
• 5. vesicles with insulin inside are pinched off from the rough endoplasmic reticulum and pass, via microtubules and motor proteins, to the Golgi apparatus
• 6. the vesicles fuse with the Golgi apparatus, where the insulin protein molecules may be modified for release
• 7. inside vesicles pinched off from the Golgi apparatus, these molecules pass to the plasma membrane
• 8. the vesicles and plasma membrane fuse, and the insulin is released to the outside of the cell