Written by Merel Dagher (PEACE Advisor)
How might we isolate cytosolic proteins from tissues, in order to purify them?
a. centrifuge the tissue at low speed; the protein is in the pellet
b. centrifuge the tissue at medium speed; the protein is in the pellet
c. centrifuge the tissue at high speed; the protein is in the supernatant
d. centrifuge the tissue at very high speed; the proteins is in the supernatant
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a. centrifuge the tissue at low speed; the protein is in the pellet
b. centrifuge the tissue at medium speed; the protein is in the pellet
c. centrifuge the tissue at high speed; the protein is in the supernatant
d. centrifuge the tissue at very high speed; the proteins is in the supernatant
Click “Read More” to see the answer.
The correct answer is d. The key to this question is realizing that we want cytosolic proteins. Performing the centrifugation at low speed will give you a pellet containing whole cells, nuclei, cytoskeletons, and plasma membranes. Performing the centrifugation at medium speed will give you a pellet containing mitochondria, lysosomes, and peroxisomes. Performing the centrifugation at high speeds will give you a pellet containing microsomes and small vesicles. Finally performing a centrifugation at very high speed will give you a pellet containing ribosomes and macromolecules, but the supernatant will contain soluble proteins.