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Biology A-level cells help?

In the CGP revision guide it says that the rough endoplasmic reticulum folds and processes proteins made by the ribosomes however i've come across many exam mark schemes which say proteins are synthesised by the rough ER.
I'm confused as to what does what, could anybody explain please?
Reply 1
Ribosomes on the rough ER is the site of translation in protein synthesis, as are ribosomes that are free in the cytosol.

There’s a level of folding and processing at the rough ER (folding to give secondary/tertiary structure and the quaternary structure of Hb is formed here), but proteins will often be transported to the Golgi apparatus for further processing and “finishing”.
Reply 2
Original post by jsg9
Ribosomes on the rough ER is the site of translation in protein synthesis, as are ribosomes that are free in the cytosol.

There’s a level of folding and processing at the rough ER (folding to give secondary/tertiary structure and the quaternary structure of Hb is formed here), but proteins will often be transported to the Golgi apparatus for further processing and “finishing”.


So the ribosomes, rough ER and golgi apparatus synthesise proteins?
Original post by Mk1237
So the ribosomes, rough ER and golgi apparatus synthesise proteins?


Not as such, proteins are only synthesised at ribsomes. They are modified by the rough ER and further modified by the golgi apparatus e.g. by addition of carbohydrates etc
Reply 4
Original post by Mk1237
So the ribosomes, rough ER and golgi apparatus synthesise proteins?


No. Ribosomes are the site of protein synthesis, but they are often found on endoplasmic reticulum - hence, “rough” ER. Other parts of the rough ER (not the ribosome), such as the lumen, is involved in processing and folding of the proteins. The Golgi apparatus further processes and finishes the final structure of the proteins ready for transport out of the cell (proteins synthesised by ribosomes on rough ER are usually extra-cellular I believe).

Only say that ribosomes or ribosomes located on the rough ER “synthesise” proteins. Then comment on rough ER and Golgi processing and folding proteins. Do not say that the rough ER and the Golgi synthesise proteins.
Reply 5
Original post by jsg9
No. Ribosomes are the site of protein synthesis, but they are often found on endoplasmic reticulum - hence, “rough” ER. Other parts of the rough ER (not the ribosome), such as the lumen, is involved in processing and folding of the proteins. The Golgi apparatus further processes and finishes the final structure of the proteins ready for transport out of the cell (proteins synthesised by ribosomes on rough ER are usually extra-cellular I believe).

Only say that ribosomes or ribosomes located on the rough ER “synthesise” proteins. Then comment on rough ER and Golgi processing and folding proteins. Do not say that the rough ER and the Golgi synthesise proteins.


Oh, okay this makes sense. Thank you!
Reply 6
Original post by whoremone
Not as such, proteins are only synthesised at ribsomes. They are modified by the rough ER and further modified by the golgi apparatus e.g. by addition of carbohydrates etc


Okay thank you :smile:

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