2.1.7 Organelles & The Production Of Proteins

Question 1

Protein Production Organelles

Answer 1

Inside cells, many organelles are involved in the production and secretion of proteins
- organelles are specialised parts of a cell that carry 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)

Question 2

Process of Protein Synthesis

Answer 2

The DNA from the nucleus is copied into a molecule of mRNA via a process known as transcription
The mRA 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 are large number 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, realising the proteins
The Golgi apparatus modified 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 (e.g. hydrolytic enzymes) or delivered to other 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 by the process of exocytosis