341fall08exam2a

341fall08exam2a - BIO 341 Principles of Cell Biology...

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BIO 341 Principles of Cell Biology Your Name ____________________ Examination 2, October 29, 2008 All marks on the answer sheet must be completed with a number 2 pencil. You must enter your full name, last name first , in the columns on the back of the answer sheet. Enter your student number in the section entitled Identification Number. Enter the version number 1 in circle 1 in the section entitled Grade or Education below the name columns. It is not necessary to fill out the other boxes. You must turn in this examination containing the multiple choice questions. Choose the answer that is most correct in the following questions and enter your answer on the front of the answer sheet: (2.5 points each) 1. With the exception of the cystic fibrosis CFTR protein, ABC transporters in eucaryotic cells a) are channel proteins for larger ions such as calcium b) transport small molecules out of the cytosol, coupled to ATP hydrolysis c) tightly bind ATP and transport it against its gradient across the plasma membrane d) transport small molecules by facilitated diffusion e) transport H + into organelles such as lysosomes in animal cells and the vacuole in plant cells 2. The membrane potential found across the plasma membrane of most animal cells is generated by a) active transport of most of the positively charged ions in the cytosol to the outside of the cell b) passive transport of most of the positively charged ions in the cytosol to the outside of the cell c) active transport of a small fraction of the positively charged ions in the cytosol to the outside of the cell d) passive transport of a small fraction of the positively charged ions in the cytosol to the outside of the cell e) active transport of a small fraction of the negatively charged ions in the cytosol to the outside of the cell 3. The procaryotic genes encoding five enzymes required for biosynthesis of the amino acid tryptophan are expressed as a group in E. coli . Expression of this group of genes is turned off when [tryptophan] is high because a) tryptophan binds directly to the operator sequence, blocking binding of RNA polymerase to the promoter b) tryptophan binds to RNA polymerase, inhibiting binding of RNA polymerase to the promoter c) tryptophan binds to the trp repressor, switching it to a conformation that cannot bind DNA d) tryptophan binds to the trp repressor, causing a conformational change so that the activated repressor binds RNA polymerase, blocking the binding of RNA polymerase to the trp promoter e) tryptophan binds to the trp repressor, causing a conformational change so that the activated repressor binds the operator sequence
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4. The plasma membrane of liver cells contains a glucose uniport that transports glucose by facilitated diffusion. When the [glucose] is higher outside the liver cell than the [glucose] inside the liver cell, the glucose uniport a) will couple the transport of glucose into the cell to the hydrolysis of ATP b) will couple the transport of glucose out of the cell to the hydrolysis of ATP
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341fall08exam2a - BIO 341 Principles of Cell Biology...

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