Exam 12: Intracellular Compartments and Protein Sorting

Indicate whether each of the following transport processes occurs via the mechanisms described as gated transport (G), transmembrane transport (T), or vesicular transport (V). Your answer would be a five-letter string composed of letters G, T, and V only, e.g. VTTTG. ( ) Import into nucleus ( ) Export from nucleus ( ) Import into mitochondria ( ) Return from Golgi to ER ( ) Return from ER to cytosol

Consider a human cell such as a hepatocyte. Which of the following compartments occupies a larger volume in the cell?

Imagine a protein that has been engineered to contain a nuclear localization signal, a nuclear export signal, a C-terminal peroxisomal targeting sequence, and a canonical endoplasmic reticulum (ER) signal sequence. With all of these signals, where would you expect to find the protein after its synthesis?

Indicate true (T) and false (F) statements below regarding the nucleus and nuclear protein transport. Your answer would be a four-letter string composed of letters T and F only, e.g. TTTF. ( ) The inner and outer nuclear membranes are continuous with each other, yet maintain distinct protein compositions. ( ) The outer nuclear membrane is studded with ribosomes engaged in protein synthesis. ( ) The endoplasmic reticulum lumen is continuous with the nuclear interior. ( ) Ribosomal proteins pass through the nuclear pore complexes twice; they are imported into the nucleus after synthesis, and are exported from the nucleus after assembly with ribosomal RNA.

Which reaction is normally catalyzed by the enzyme catalase in the peroxisome?

Indicate whether each of the following descriptions better matches the rough (R) or the smooth (S) endoplasmic reticulum (ER). Your answer would be a five-letter string composed of letters R and S only, e.g. SRSRR. ( ) It mostly has a tubular appearance. ( ) It contains the transitional ER. ( ) It is coated by ribosomes. ( ) It can be specialized for functions such as detoxification and lipid metabolism. ( ) Sarcoplasmic reticulum in muscle cells is one of its specialized forms.