Question

3. (4 points) Briefly describe the path a protein made by ribosomes that are attached to the endoplasmic reticulum will follow through the endomembrane system in order to be exported from the cell. Include in your answer which other organelles the protein will move through, how the protein is moved from one organelle to another, and the process that a cell would use to export the protein. 4. Fill in the diagram below with what you learned about the cell cycle. Label each phase with one of these terms: interphase, prophase, metaphase, anaphase, telophase/cytokinesis. Make sure to show what happens to the nucleus and the chromosomes in each phase. (5 points) OOOOO

Answer 1

3) Protein made by ribosomes that are attached to endoplasmic reticulum follow the following pathway through the endomembrane system --

Initiation of Protein synthesis occur in free form of ribosome after that ribosome bound to ER membrane .

1) As the signal sequence emerges from the ribosome , it is recognised and bound by signal recognition particle (SRP)

2) SRP escorts tha complex to ER membrane where it binds to SRP receptor

3) SRP is released, ribosome binds to translocon and signal sequence is inserted into membrane channel.

4) Translation resumes and growing polypeptide is translocated across membrane.

5) cleavage of signal sequence by signal peptidase releases the polypeptide into lumen of ER. In the lumen of ER processing of protein will occur like a) chemical modification ( glycosylation) b) folding c) assembly of multi subunit protein d) splicing e) cutting

After that ER protein with retention signal will remain in ER while the protein without retention signal will move to Golgi bodies , lysosome or outside the cell .

The protein move from 1)ER to Golgi then from 2) Golgi to lysosome or from Golgi to plasma membrane through TRANSPORT VESICLES.

In Golgi further chemical modifications of protien will takes place and after that protein will move either to lysosome or to plasma membrane .