Term
| Which of the following are examples of regulation of gene expression? |
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Definition
-Repressor, operator, inducer of the lac operon in escherichia coli
-Attenuation in the trp operon in Escherichia coli
-Inversion of a promoter affecting salmonella typhi surface antigens |
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Term
| A number of tumor viruses of humans have been shown to carry chromosomal genes that are responsible for the virus's tumor-inducing properties. Which of the following are possible mechanisms for the presence of chromosomal genes on tumor viruses? |
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Definition
| The tumor-inducing genes were transposed fromt he chromosome to the viral genome by transposable genetic elements |
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Term
Level of regulation of gene expression:
Intron removal and formation of alternative mRNAs |
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Definition
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Term
Level of regulation of gene expression:
Addition of carbohydrates to proteins |
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Definition
| posttranslational and modification |
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Term
level of regulation of gene expression:
Cleavage of amino acid sequences in proteins |
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Definition
| posttranslational and modification |
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Term
Level of regulation of gene expression:
Binding of regulatory proteins to operators |
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Definition
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Term
Level of regulation of gene expression:
Poly adenylation of mRNA |
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Definition
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Term
| What would be the effect of a deletion of 5 bases between the -10 and -35 sequences in a bacterial promoter? |
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Definition
| A decrease in RNA polymerase binding |
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Term
| What term describes the expression of the B-galactosidease gene of the lac operon in a srain of Escherichia coli in which there is a mutation in the lacI gene resulting in a loss of operator binding? |
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Definition
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Term
| Which of the following is responsible for the binding of mrNA to the ribosome? |
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Definition
| Hybridization between sequences at the 5' end of mRNA and the 3' end of the small subunit rRNA |
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Term
| Which of the following describes the action of the tryptophan aporepressor? |
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Definition
| the tryptophan aporepressor binds to the trpO gene when tryptophan is present |
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Term
| You isolate the tRNA for tryptophan (i.e. tRNAtrp) and link the amino acid histidine to the 3'-CAA sequence of that tRNA. AFter linkage you mix the resulitng tRNAtrp linked to histidine with the aminoacyl tRNA synthetase for tryptophan. Which of the following would be observed? |
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Definition
| cleavage of the histidine from the tRNAtrp |
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Term
| What would be the effect on transcription of changing the -10 sequence in a bacterial promoter from TATAAT to TAGCCT? |
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Definition
| Decrease in the initiation of mRNA synthesis |
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Term
| At the 5'-end of each intron is a sequence 5'-GU (A/G)AGU-3'. What would be the effect of deleting that sequence? |
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Definition
| No more removal of that particular intron |
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Term
| Is the association between histone proteins and DNA a form of regulation of gene expression? |
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Definition
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Term
| What term describes the expression of the B-galactosidase gene of the lac operon in a strain of Escherichia coli in which there is a mutation in the lacI gene resulting in a loss of lactose bindings? |
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Definition
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Term
| Attenuation is the sole mechanism of regulation of the genes of the histidine operon (his) in Escherichia coli. Which of the following would be characteristic of that regulation? |
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Definition
| the his atttenuator protein is rich in histidine |
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Term
| The primary structure of a protein is |
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Definition
| the sequence of amino acids |
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Term
| Which of following are examples of instances where hybridization of nucleic acid sequences can be involved in gene expression in bacteria or eukaryotes? |
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Definition
-Termination of mRNA synthesis
-Initiation of protein synthesis
-Protein synthesis
-mRNA translation
(Answers 2, 3, 4, 5) |
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Term
| You have been hired by a biotechnology company with the objective of producing the human protein, insulin, in bacterial cells. Which of the following approaches would result in the expression of the insulin gene in a bacterial cell? |
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Definition
| Get rid of the insulin gene's promoter and use a promoter from the bacterial cell for transcription |
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Term
| What term describes the expression of the B-galactosidase gene of the lac operon in a strain of Escherichia coli in which there is a mutation in the lacO gene resulting in a loss of repressor binding? |
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Definition
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Term
| Compared to bacterial transcription, transcription in plants and animals is |
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Definition
| subject to more modulation by assessory proteins |
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Term
| You map a mutation in a gene and find that is it located near the 5' end of the mRNA. Where would the changed amino acid be located in the protein |
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Definition
| at the amino-or N-terminus of the protein |
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Term
| Which of the following RNA types is involved in removal of introns in pre-mRNA? |
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Definition
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Term
| Mutations in the anticodon of a tRNA can supress a missense mutation in a protein-encoding gene. |
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Definition
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Term
| What is the translation initiation codon? |
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Definition
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Term
| Which of the following are differences between bacterial and Eukaryotic mRNAs/ |
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Definition
| Eukaryotic mRNA often contain long 3'-polyA |
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Term
| What is the meaning of the term 'heterochromatic' |
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Definition
| DNA that is always bound with protein throughout the cell cycle |
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Term
| What would be the most likley effect of a mutation in an intron in the amino acid sequence of the prtein? |
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Definition
| It is unlikely there would be any change, unless the 5' and 3' conserved sequences were altered |
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Term
| do conditions in cells favor hydrogen bond formation? |
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Definition
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Term
| You grow a strain of Escherichia coli in medium where the only carbon source is lactose and it produces B-galactosidase. If you grow the strain in glucose as the only carbon source, there is no production of B-galactosidase. Which of the following describes the production of B-galactosidase if the strain is grown in the presence of both glucose and lactose? |
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Definition
| The prsence of glucose will prevent induction of B-galactosidase by lactose |
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Term
| Why does the presence of any one of the three chian-terminating codons lead to the cessation of protein synthesis and release of the newly made protein? |
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Definition
| There are no tRNAs that recognize those three codons |
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Term
| In the regulation of biosynthetic operons, such as that for tryptophan biosynthesis (trp), addition of the end product(tryptophan) has what effect on expression of the genes of the operon |
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Definition
| represses expression o fthe genes of the operon |
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Term
| What would be the consequence on transcription of the trp operon of deletion of the attenuator sequence? |
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Definition
| trp operon transcription would not be repressed as much by tryptophan |
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Term
| What would be the effect of a mutation replacing 3 bases between the -10 and -35 sequence with 3 other bases in a bacterial promoter? |
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Definition
| no effect in RNA polymerase binding |
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Term
| Which of the followinga re problems that would be expected to be encountered in trying to express a bacterial gene in plant cells |
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Definition
| the bacterial promoter would not be recognized by the plan tRNA polymerase |
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Term
| A mutation in the tryptophan aporepressor gene (trpR) abolishing the ability of the aporepressor to bind to the trp0 gene results in which of the following |
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Definition
| Constitutive synthesis of the trp operon mRNA |
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Term
| Which of the following is not a possible mechanism for control of gene expression in eukaryotes? |
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Definition
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Term
| Genes for regulatory proteins |
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Definition
| don't have to be closely linked to the operon they regulate |
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Term
| In transcription, negative regulation indicates: |
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Definition
| when the regulator protein is bound to DNA, there is no transcription |
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Term
| What would be the effect on expression of the lac operon of a mutation resulting in loss of adenyl cyclase activity; the enzyme that produces cAMP from ATP? |
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Definition
| no more induction of the lac operon |
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Term
| which of the following dexcribes an inducible protein? |
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Definition
| the protein is produced when the inducer is present |
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Term
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Definition
| the site for binding repressor |
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Term
| which of the following could be mutations resulting in constitutive synthesis of the enzymes of tryptophan syntehsis in a strain of escherichia coli? |
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Definition
-a mutation in the trpR repressor gene leading to loss of binding of tryptophan
-A mutation of the trpO operator gene leading to a loss of trpR respressor binding |
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Term
| Why is the lac operon of Escherichia coli not inducible in rapidly growing cells? |
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Definition
| rapidly growing cells have low concentrations of cAMP |
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Term
| In transcription, positive regulation indicates |
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Definition
| when the regulator protein is bound to DNA, there is transcripton |
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Term
| What is the funciton of the N-formyl group o f methionine on protein synthesis? |
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Definition
| it is a blocking group to prevent formation of peptide bonds in the wrong direction |
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Term
| Which of the following terms describes the genetic code as it is employed in cells for protein synthesis? |
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Definition
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Term
| an artifical mRNA is produced from ATP and GTP using polynucleotide phosphorylase and used to direct the synthesis of a protein in a cell-gree, mRNA-depedent protein sytnhesizing system. What would be the percent composition of arginine (ARG) in the resulting protein? |
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Definition
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Term
| Attenuation, as exemplified by the trp operon, invovles transcription and translation of an attenuation protein that has which of the following characteristics? |
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Definition
| Proportionately a high percentage of tryptophans |
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Term
| Attenuation, as exemplified by the trp operon, invovles transcription and translation of an attenuation protein that has which of the following characteristics? |
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Definition
| Proportionately a high percentage of tryptophans |
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