• In cells,?many organelles?are involved in the?production?and?secretion?of?proteins
• Organelles are?specialised parts of a cell?that carry out a particular function
  • Some organelles are membrane-bound

   

• The organelles involved in protein synthesis include:
  • Nucleus
  • Ribosomes
  • Rough endoplasmic reticulum (RER)
  • Golgi apparatus
  • Cell surface membrane

   

• The?nucleus?stores the?DNA?(that codes for the production of proteins) and also contains the?nucleolus, which manufactures?ribosomes?(required for protein synthesis)
  • The DNA from the nucleus is copied into a molecule of?mRNA?via a process known as?transcription

   

• The mRNA strand?leaves?the nucleus through a?nuclear pore?and attaches to a?ribosome?on the?rough endoplasmic reticulum
  • The ribosome 'reads' the genetic instructions contained within the mRNA and uses this code to?synthesise a protein?via a process known as?translation
  • This protein then passes into the lumen (the inside space) of the?rough endoplasmic reticulum?to be?folded?and?processed
  • Cells that produce a large amount of proteins (e.g. enzyme or hormone-producing cells) have an?extensive?rough endoplasmic reticulum

   

• The processed proteins are then transported to the?Golgi apparatus?(also known as the Golgi body or Golgi complex) in?vesicles, which fuse with the Golgi apparatus, releasing the proteins
  • The Golgi apparatus?modifies?the proteins, preparing them for?secretion
  • Proteins that go through the Golgi apparatus are usually exported (e.g. hormones such as insulin), put into lysosomes (such as hydrolytic enzymes) or delivered to other membrane-bound organelles
  • The modified proteins then leave the Golgi apparatus in?vesicles

   

• Finally, these vesicles (containing the final proteins) fuse with the?cell surface membrane, releasing the proteins

Many organelles are involved in the production and secretion of proteins