Only 11% of test takers picked the right answer from a test with 5 multiple choice answers. That's right only 11% of test takers got this answer right on a test with 5 multiple choice answers. If one were to pick randomly they would of had a 9% greater chance of marking the right answer. Targeting of a newly synthesized protein is most likely to require two different signal peptides for which of the following destinations? (A) Plasma Membrane (B) Lysosome (C) Cytosol (D) Chloroplast (E) Endoplasmic Reticulum
Well, since the question didn't specify that the protein is synthesized in plant cells only, we have to assume that it could be referring to plant or animal cells... So can we eliminate (D) Chloroplast as an answer?
This is a ‘cagey’ question because Proteins are fed into the ER (endoplasmic reticulum) during translation if they have a signal peptide and if they, have another signal peptide they can be sent to the mitochondria, chloroplasts, peroxisomes, or nucleus after translation. However, the only choice they give you out of these organelles in the multi-choice test are Chloroplasts. Therefore, chloroplasts are actually the right answer.
I was thinking the answer was the ER, but I see what you mean. They had me fooled, I eliminated the correct answer because of faulty logic on my part.
It's a tricky question because a protein does indeed need a signal peptide to go to the ER. But the only other organelles that require another signal pathway are the mitochondria, peroxisomes, and nucleus. I can imagine another question on the GRE asking the same question just using one of the other three organelles requiring a signal peptide with the other multiple choice questions not requiring another signal peptide.
