Reference no: EM132158223

1.Which is more stable - GTP or GMP? Why?

2.A budding yeast transcription factor gene sequence contains a mutation that removes the signal sequence of the protein that is encoded. The final destination of this transcription factor is the nucleus. In what cellular location would the transcription factor protein normally be synthesized? As a consequence of the signal sequence mutation, where will the transcription factor protein end up?

3.The Na+ / K+ pump is a transmembrane protein in eukaryotic cells. Describe the cellular location where this protein is synthesized

4a.The interior of a cell is an organized place and proteins, therefore, have cellular addresses. Using arrows, describe the path of a lysosomal hydrolase enzyme between its synthesis site in ER-bound ribosomes and its final destination in lysosomes. Include all relevant organelles and vesicles.

4b. The drug Brefeldin A (BFA) prevents the formation of transport vesicles within the ER. How would this drug affect the transport of lysosomal hydrolase enzymes to lysosomes? Explain where lysosomal hydrolase enzymes would be located in cells treated with BFA.

5.Melanosomes are specialized vesicles that store pigment molecules inside cells called melanocytes. These pigment molecules are released from melanocytes by exocytosis. Cells such as skin and hair cells then take up the pigment by endocytosis, which accounts for their characteristic pigmentation. Mice with a mutation in the Rab27A gene have a lightened coat color due to decreased pigmentation. Describe a specific process in melanosome exocytosis that could be defective in mice with a Rab27A gene mutation.

6.Cells take in materials from the extracellular space by endocytosis, which requires the use of plasma membrane to enclose materials within a vesicle. It would take too much energy for cells to continually synthesize new plasma membrane to replace the membrane that is used to form these vesicles. Yet the plasma membrane of cells that are continually endocytosing material does not become smaller and smaller. So, given your understanding of the endomembrane system, where does the membrane come from?

7.An extraterrestrial bacterial species has just been identified! This species lives on super-Earth, an exoplanet that has an atmosphere filled with hydrogen cyanide. Your task is to study how this incredible species manages to avoid the toxic effects of cyanide (CN). You discover that the bacterial cells have a transmembrane protein in the plasma membrane that efficiently transports CN out of the cell. Is the transport of CN by this transmembrane protein likely to require an input of energy, or can it occur even in the absence of an energy source? Explain your answer.

8.The movement of water across the plasma membrane is facilitated by water channels called Aquaporins. Maintaining homeostasis in the water content of alveolar cells that line the vertebrate lungs is critical for proper breathing. Alveolar cell "flooding" can cause inefficient oxygenation and a condition known as pulmonary edema. In contrast, alveolar cell dehydration can lead to mucus build-up in the airways. For an alveolar cell containing aquaporins, describe how a decrease in intracellular Na+ ion levels would affect alveolar cell volume - would this lead to "flooding" or dehydration? Explain briefly.