Question

Describe a protein's path through the cell, starting with mRNA molecule that specifies the protein that requires modification in the Golgi apparatus.

a) The mRNA molecule is translated in the cytoplasm, resulting in a polypeptide chain. The polypeptide undergoes post-translational modification in the Golgi apparatus and is then packaged into vesicles. These vesicles travel to the cell membrane, where the protein is released into the extracellular space.
b) The mRNA molecule is transcribed in the nucleus and exported to the cytoplasm. Ribosomes translate the mRNA into a polypeptide chain, which is then transported to the Golgi apparatus. In the Golgi, the protein is modified and sorted into vesicles for secretion.
c) The mRNA molecule is replicated in the nucleus and exported to the cytoplasm. The ribosomes attach to the mRNA and initiate translation, producing a protein. This protein is transported to the lysosomes for degradation and recycling.
d) The mRNA molecule is transcribed in the nucleus and translated by ribosomes in the cytoplasm, forming a protein. This protein is transported to the mitochondria, where it undergoes further modification and contributes to energy production.

Answer 1

A protein's path in the cell begins with mRNA transcription in the nucleus and ends with protein secretion outside of the cell. The mRNA is translated into a protein by ribosomes, and then directed to the ER for initial folding. The protein is then modified in the Golgi apparatus, packaged into vesicles and secreted.

Step-by-step explanation:

The path of a protein within a cell, starting with the mRNA molecule that specifies the protein and ending with modification in the Golgi apparatus, involves several steps:

1. 
   
3. The mRNA molecule is transcribed in the nucleus and is then exported to the cytoplasm.
4. 
   
6. Once in the cytoplasm, the mRNA is translated into a polypeptide chain by ribosomes.
7. 
   
9. This polypeptide chain is recognized by a signal recognition particle if it contains a signal sequence, halting translation temporarily.
10. 
    
12. The mRNA-ribosome complex is directed to the endoplasmic reticulum (ER), where translation resumes, and the synthesis of the protein on the ribosome continues.
13. 
    
15. As the newly-synthesized protein emerges into the ER, it undergoes initial modification and folding.
16. 
    
18. After that, the protein is transported to the Golgi apparatus for further modifications.
19. 
    
21. Modified proteins are then tagged and packaged into secretory vesicles that bud from the Golgi's trans face.
22. 
    
24. Finally, these vesicles travel to the plasma membrane, where they fuse with the membrane and release their contents outside the cell.