Question

The DNA in a cell's nucleus encodes proteins that are eventually targeted to every membrane and compartment in the cell, as well as proteins that are targeted for secretion from the cell.For example, consider these two proteins:1. Phosphofructokinase (PFK) is an enzyme that functions in the cytoplasm duringglycolysis.2. Insulin, a protein that regulates blood sugar levels, is secreted from specializedpancreatic cells.Assume that you can track the cellular locations of these two proteins from the time that translation is complete until the proteins reach their final destinations.For each protein, identify its targeting pathway: the sequence of cellular locations in which the protein is found from when translation is complete until it reaches its final (functional) destination. (Note that if an organelle is listed in a pathway, the location implied is inside the organelle, not in the membrane that surrounds the organelle.)Options:a. Cytoplasm only, ER --> cytoplasm, ER --> Golgi --> outside cell, b. cytoplasm --> ER --> outside cell, c. Golgi --> ER --> outside cell, d. cytoplasm --> Golgi --> outside cell, e. nucleus --> cytoplasm, ER --> Golgi --> cytoplasm

Answer 1

Answer:

PFK

nucleus-->cytoplasm-->ER (ribosomes, translation will occur)-->Golgi body(for packaging)-->cytoplasm (specified compartment inside the cell)

insulin

nucleus-->cytoplasm-->ER (ribosomes, translation will occur)-->Golgi body(for packaging)-->outside the cell.

Explanation:

considering PFK (Phospho Fructo Kinase), for the nucleus the mRNA will be transferred to the cytoplasm on the (RER) rough endoplasmic reticulum the mRNA will be translated on ribosomes, then the packaging will be done inside Golgi apparatus, and then the protein inside the vacuole will be transported to the specialized compartment. in the case of insulin the process will be same but the desired target will be blood hence it will be transported out of the plasma membrane of islets of Langerhans  into the blood capillaries.

Answer 2

Answer:

The correct answer is:

e. nucleus --> cytoplasm, ER --> Golgi --> cytoplasm

Explanation:

The DNA from the nucleus is transcribed into m RNA. This m RNA then moves out from nucleus into the cytoplasm. From the cytoplasm the mRNA is processed in the endoplasmic reticulum. The endoplasmic reticulum has ribosomes which are involved in protein synthesis. The newly synthesized proteins is transported over to the Golgi apparatus. There the proteins is further processed by modifying and encasing them into vesicles. After this they are transported to cells.