I have this question about DNA and protein... Help please!?

Question

Proteins are manufactured from the "blueprints" found on DNA. After they are translated, they are moved through a system of internal membranes before being distributed throughout the rest of the cell. At some point in this process, they are modified to their functional form.

• Describe the movement of proteins from their manufacturing point through this internal membrane system.

• Discuss the role of each of the following structures in the whole process: cell membrane, vesicles (at two points in the process), ribosomes, Golgi apparatus, and endoplasmc reticulum. Be sure to identify the correct order in which the proteins move through each of these structures.

Answers don't have to be long. Please help me!!

Thank you! =)

Answer 1

Here is a description of protein processing for export.

Hope it helps.

A protein for export will have a signal peptide that will associate with an SRP (SEE below for SRP cycle) that will halt synthesis, from the mRNA produced by transcription in the nucleus, until it comes in contact with rough ER docking site and translation will resume. The signal peptide will be cleaved with signal peptidase. Then the protein will be brought to the cis-side of the Golgi via transitory vesicles where it will be further processed. The protein probably binds to a receptor side on the trans side of the Golgi and a secretory vesicle is formed with the protein inside. The secretory vesicle moves towards the plasma membrane where it fuses with the membrane, the protein is released and the secretory vesicle membrane becomes part of the plasma membrane.(exocytosis)

http://cr.middlebury.edu/biology/SCB2-de...

The SRP cycle

The signal recognition particle (SRP) associates with ribosomes that are in the process of translating the mRNA for a secretory protein. The protein has a signal at the N-terminus. Subsequently, the ribosome-bound SRP interacts with the SRP-receptor, a component of the ER membrane. Finally, SRP recycles to associate with another ribosome, and translation continues with the secretory protein transversing the membrane through a channel called the translocon and entering the lumen of the rough ER.

http://bio.lundberg.gu.se/dbs/SRPDB/Stru...