front 1 Structural motif | back 1 Common structures found in regulatory proteins that allow interactions between protein amino acids and nucleotides in major and minor grooves |
front 2 Enhancers | back 2 Regulate the timing and spatial patterns of gene expression |
front 3 Strong purifying selection | back 3 Reduced rate of evolution of enhancers at regions that bind to protein; prevents evolutionary change. |
front 4 Sonic hedgehog (SHH) | back 4 Important regulator in several developmental pathways, including limb development |
front 5 Insulator sequences | back 5 cis-acting, protein-binding sequences that prevent enhancers from turning on the wrong genes and turning on the right genes at the right time. |
front 6 Chromatin packagin is caused by.... | back 6 Interactions between DNA and histones, forming nucleosomes. |
front 7 What do Covered promoters do? | back 7 Characterize genes that are regulated, and require the remodeling or movement of nucleosomes to allow transcription activators to bind. |
front 8 What does Chromatin remodelers do? | back 8 Reorganize nucleosomes by sliding, moving, or modifying their protein composition. |
front 9 What does Chromatin modifiers do? | back 9 Add acetyl or methyl groups to histones to activate or repress gene activity, respectively. |
front 10 DNA histone interactions are weak and regulatory sequences are accessible; transcription proceeds | back 10 Open chromatin |
front 11 DNA histone interactions are strong and regulatory sequences are not accessible; transcription is silent. | back 11 Closed chromatin |
front 12 DNase I hypersensitivity | back 12 can identify open and closed chromatin |
front 13 Methylated histones; Unmethylated histones | back 13 Close chromatin; Open chromatin |
front 14 In negative control, what molecule would you expect to find bound to the operator if there is no transcription? A) activator B) repressor C) inducer D) corepressor E) RNA polymerase | back 14 B) repressor |
front 15 You want to design a repressor protein mutant. Which protein domain is the best target for preventing binding of the corepressor? A) DNA-binding domain B) allosteric domain C) promoter domain D) helix-turn-helix domain E) activator binding site | back 15 B) allosteric domain |
front 16 The presence of which combination of molecules would lead to active transcription of an operon? A) activator + corepressor B) activator + repressor C) inducer + corepressor D) repressor + corepressor E) activator + inducer | back 16 E) activator + inducer |
front 17 In the lac operon, what acts as the inducer? A) glucose B) permease C) allolactose D) β-galactosidase E) transacetylase | back 17 C) allolactose |
front 18 The enzyme β-galactosidase catalyzes what reaction? A) allolactose → glucose + lactose B) lactose → glucose + fructose C) lactose → galactose + glucose D) glucose → galactose + lactose E) galactose → glucose + lactose | back 18 C) lactose → galactose + glucose |
front 19 A bacterium is unable to transport lactose into the cell to be broken down. Which gene is likely mutated in this bacterium? A) lacZ B) lacY C) lacI D) lacP E) lacO | back 19 B) lacY |
front 20 Which region of the lac operon would you target if you want to disrupt the -10 and -35 consensus sequences? A) lacZ B) lacY C) lacI D) lacP E) lacO | back 20 D) lacP |
front 21 In the presence of glucose, where is the lac repressor bound? A) lacZ B) lacO C) lacP D) lacI E) The lac repressor is not bound to the operon. | back 21 B) lacO |
front 22 Which structural gene of the lac operon can be mutated without affecting the cell's ability to break down lactose? A) lacZ B) lacY C) lacA D) lacP E) lacO | back 22 C) lacA |
front 23 Which of the following are constitutive mutants of the lac operon? A) lacZ and lacP B) lacZ and lacI C) lacO and lacI D) lacO and lacZ E) lacI and lacY | back 23 C) lacO and lacI |
front 24 Which mutants are noninducible? A) lacIS B) lacI- C) lacI+ D) lacOC E) lacO+ | back 24 A) lacIS |
front 25 Which of these haploid strains produce β-galactosidase constitutively but do not produce permease? A) I- P+ O+ Z+ Y+ B) I+ P+ O+ Z- Y- C) I- P+ O+ Z-Y+ D) I+ P+ O- Z+ Y+ E) I- P+ O+ Z+ Y- | back 25 E) I- P+ O+ Z+ Y- |
front 26 Which of these haploid strains produce permease but do not produce β-galactosidase? A) I- P+ O+ Z+ Y+ B) I+ P+ O+ Z-Y+ C) I- P+ O+ Z-Y- D) I+ P+ O- Z+ Y+ E) I- P+ O+ Z+ Y- | back 26 B) I+ P+ O+ Z-Y+ |
front 27 During the attenuation of the trp operon, which stem loop leads to polycistronic mRNA synthesis during tryptophan starvation? A) 1-3 (antitermination) stem loop B) 3-4 (termination) stem loop C) 1-2 (pause) stem loop D) 2-3 (antitermination) stem loop E) 2-4 (termination) stem loop | back 27 D) 2-3 (antitermination) stem loop |
front 28 In the absence of tryptophan, A) the inactive repressor cannot bind trpO, so operon gene transcription occurs. B) the active repressor binds trpP, so operon gene transcription is repressed. C) the inducer cannot bind trpO, so operon gene transcription occurs. D) the active repressor cannot bind trpO, so operon gene transcription is attenuated. E) the repressor binds the corepressor, and operon gene transcription occurs. | back 28 A) the inactive repressor cannot bind trpO, so operon gene transcription occurs. |
front 29 Which sigma factor, encoded by the rpoH gene, is active at high temperatures? A) σ70 B) σ32 C) σ45 D) σ37 E) σ50 | back 29 B) σ32 |
front 30 Which enzyme is responsible for integration of a temperate phage into a host genome? A) β-galactosidase B) transposase C) integrase D) transacetylase E) permease | back 30 C) integrase |
front 31 Which region of the lambda phage genome enables the linear chromosome to circularize when it enters a host cell? A) cohesive (cos) site B) IS10 C) early operators D) integrase (int) gene E) excisionase (xis) gene | back 31 A) cohesive (cos) site |
front 32 If you wanted to prevent a cell from entering the lysogenic pathway, which gene controlled by PRM would you target? A) cro B) Q C) cI D) cII E) O | back 32 C) cI |
front 33 In λ phage, which protein, the product of the cI gene, blocks the transcription required to initiate the lytic cycle? A) cro B) repressor C) enhancer D) integrase E) operator | back 33 B) repressor |
front 34 Regulation of transcription of bacterial genes takes place at which two levels? | back 34 Answer: initiation and amount |
front 35 What are the two active sites or "domains" on a repressor protein? | back 35 Answer: DNA-binding and allosteric |
front 36 If a corepressor is inhibited, what effect would you expect to see in the operon? | back 36 Answer: Transcription will occur. |
front 37 Which proteins facilitate RNA polymerase binding at promoters? | back 37 Answer: activator proteins |
front 38 Catabolite repression refers to the repression of the lac operon in the presence of which catabolite? | back 38 Answer: glucose |
front 39 Binding of which complex increases the ability of RNA polymerase to transcribe the lac operon? | back 39 Answer: CAP-cAMP |
front 40 Which enzyme is the product of the lacZ gene? | back 40 Answer: β-galactosidase |
front 41 Which part of the lac operon is cis-dominant? | back 41 Answer: lacO |
front 42 Which part of the lac operon produces a regulatory protein that is trans-acting? | back 42 Answer: lacI |
front 43 In the absence of both glucose and lactose, the presence of which molecule is capable of inducing basal transcription? | back 43 Answer: cAMP |
front 44 Which protein in the arabinose operon is responsible for both positive and negative regulation of transcription? | back 44 Answer: araC |
front 45 In the trp operon, where is the attenuator region located? | back 45 Answer: trpL |
front 46 Which molecule functions as the corepressor in the trp operon? | back 46 Answer: tryptophan |
front 47 What are the three possible alternative stem loops that can form in mRNA? | back 47 Answer: pause, antitermination, and termination |
front 48 Mutations of trpL decrease the efficiency of transcriptional regulation by disrupting the formation of which stem-loop structure? | back 48 Answer: 3-4 (termination) loop |
front 49 Bacteria grown at 45°C initiate expression of which two types of proteins? | back 49 Answer: heat shock and chaperone |
front 50 Antisense control of translation involves the regulation of which enzyme produced by bacterial insertion sequence IS10? | back 50 Answer: transposase |
front 51 The genetic switch controlling whether a bacterium enters the lytic or lysogenic cycle relies on the binding of which two proteins? | back 51 Answer: cro and λ repressor |
front 52 What is the process by which a bacterium switches from a lysogenic to lytic cycle? | back 52 Answer: induction |
front 53 What protein cleaves the λ repressor monomers to inactivate the repressor protein, and is activated by DNA-damaging agents? | back 53 Answer: RecA |
front 54 Most of the regulation of gene expression in bacteria occurs at the ________ level. | back 54 Answer: transcriptional |
front 55 Changing conformation at the active site as a result of binding a substance at a different site is known as ________. | back 55 Answer: allostery |
front 56 Expression of a(n) ________ alters gene transcription in E. coli by activating transcription of specialized heat stress response genes. | back 56 Answer: alternative sigma factor |
front 57 Bacterial translation is inhibited by ________ RNA, which is complementary to a portion of a specific mRNA. | back 57 Answer: antisense |
front 58 In λ phage, entry into the ________ cycle requires transcription of late genes. | back 58 Answer: lytic |