QB08-B - BIO320-Spring 2008 Question bank B REGULATING GENE...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
BIO320-Spring 2008 Question bank B 1 mkernan 2008 REGULATING GENE EXPRESSION IN PROKARYOTES SIGMA PROTEINS 1. One way that bacteria can tailor their gene expression to changing conditions is by activating different sigma proteins. Genes activated by different sigma proteins probably have different: A) translation initiator codons B) operator sequences C) core RNA polymerases D) ribosome binding sites E) promoter sequences OPERON STRUCTURE & REGULATION 2 . Which of the following statements about the structural genes in the lac operon of E. coli is false : A) The genes are closely linked on a recombination map. B) The gene products perform different functions in a single biochemical pathway. C) The genes are transcribed into a single polycistronic transcript. D) The genes are translated into a single polyprotein which is then cleaved into separate proteins. E) The genes are coordinately regulated. 3. A polycistronic message, such as that transcribed from a bacterial operon, may have A. A single promoter but several transcription start sites. B. A single transcription start site but several open reading frames. C. A single translation start codon but several stop codons. D. Several transcription start sites and several stop codons. E. Several promoters and several open reading frames. 4 . A bacterial operon encodes several enzymes that together convert amino acid X into amino acid Z, which is essential for growth. Would you expect expression of this operon to be. .. A. Repressed in the presence of amino acid X. B. Repressed in the presence of amino acid Z. C. Repressed in the absence of amino acid Z. D. Activated (derepressed) in the absence of amino acid X. E. Activated (derepressed) in the presence of amino acid Z. 5. Repressor proteins can recognize specific DNA segments because of contacts made between: A. Peptide bonds in the protein and the ribose rings in the DNA B Amino acid side chains in the protein and the bases in the the DNA C. Amino acid side chains in the protein and the phosphates in the DNA D. The amino terminus of the protein and the 5’ end of the DNA E. The carboxy terminus of the protein and the 3’ end of the DNA 6 . When the lac repressor binds an inducer, it undergoes an allosteric shift. Is this likely to change its: A. primary structure B. secondary structure C. tertiary structure D. (A, B and C) E. none of the above 7. A partially diploid bacterial cell with the lac operon genotype lac I + P + O + Z Y + / F’ lac I + P + O + Z + Y has a normal phenotype for production of the enzymes galactosidase (encoded by lacZ ) and permease (encoded by lacY ). This fact is an example of: A) Complementation B) Catabolite activation C) Cis-dominance D) Allostery E) Recombination 8. + Z + x F lac I - Z - . They found that the F- cells began to express galactosidase (the lacZ gene product) soon after
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 09/28/2009 for the course BIO 320 taught by Professor N/a during the Spring '08 term at SUNY Stony Brook.

Page1 / 8

QB08-B - BIO320-Spring 2008 Question bank B REGULATING GENE...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online