Question
General Instructions: Work out the answers on paper first: you have TWO tries online before the deadline. Each question is worth 1 point for a correct answer, with no penalty for incorrect answers. Submitting this quiz before the deadline earns 6 points for participation. TOTAL OF 10 QUESTIONS in this quiz. CALCULATIONS MAY BE REQUIRED FOR SOME QUESTIONS We are harvesting a protein that is expressed in bacterial host cells. We broke the cell walls and membranes and performed centrifugation. Which of the following types of molecules is LEAST likely to be in the pellet? A1. Chromosomal DNA. A2. Free amino acids from hydrolyzed proteins. A3. Proteins that have precipitated. A4. Ribosomes. A5. All equally likely. The procedure for purifying a certain enzyme calls for centrifugation of the homogenate, then adding ammonium sulfate to the supernatant, and then a second centrifugation with the supernatant being retained and subsequently dialyzed. Which of the following statements is most likely TRUE? A1. The enzyme of interest precipitated when ammonium sulfate was added. A2. A benefit of dialysis is to remove impurities like chromosomal DNA. A3. Cellular organelles like mitochondria would be removed in die first centrifugation pellet. A4. Enzyme assays cannot be performed until after the dialysis is completed. A5. All of the above are false. Dialysis and chromatography both can be used to separate different molecular species. Which of
Explanation / Answer
ANSWERS
MH4-HW-O1
ANSWER IS A5- ALL EQUALLY LIKELY
BECAUSE ON HYDROLYSIS FROM BACTERIAL CELL THERE WILL EXTRACTION OF CHROMOSOMAL DNA (INVOLVED IN REPLICATION), RIBOSOMES WILL BE THERE(BIND TO mRNA FOR PROTEIN SYNTHESIS), FREE AMINO ACID ( INVOLVED IN PROTEIN FORMATION) AND PROTEIN PRECPITATED.
M4-HW-02
ANSWER IS A1 THE ENZYME OF INTEREST IS PRECIPITATED BY AMMONIUM SULPHATE SOLUTION THUS CONCENTRATNG THE PROTEIN AND SEPERATING IT FROM CARBOHYDRATES, NUCLEOTIDES, FREE AMINO ACIDS. CONCENTRATION OF AMMONIUM SULFATE IS INCREASED TO PRECIPITATE ENZYME BASED PROTEINS.
