question

1. What are Bacterial chromosomes made up of?

answer

1. Double stranded DNA

question

2. What form are most (50%) or Bacterial chromosomes in?

answer

2. Single circular molecule, 1-9 Mb

question

3. What other forms do bacterial chromosomes take?

answer

3. Single circular molecule, more than one circular molecule, single linear molecule, more than one linear molecule

question

4. T/F Extrachromosomal elements are essential for bacterial growth.

answer

4. F – not essential for bacterial growth under normal circumstances

question

5. What 2 forms of extrachromosomal elements are there in bacteria?

answer

5. Plasmids, Bacteriophages

question

6. What are some variable chromosomal elements that are present in some strains and not others?

answer

6. Integrated Plasmids and bacteriophages, Remnants of plasmids and bacteriophages, transposable elements, Pathogenicity islands

question

7. What is a large contiguous block of DNA encoding groups of genes involved in pathogenesis called?

answer

7. Pathogenicity Island

question

8. What types of things do Pathogenicity Islands encode for?

answer

8. Virulence factors – toxins, secretion systems, pili, ect.

question

9. How can P. Islands be recognized?

answer

9. Often have different G+C content then the rest of the chromosome

question

10. How are P. Islands thought to have originated?

answer

10. Horizontal gene transfer

question

11. What are the 3 types of Recombination?

answer

11. Homologous, Site-specific, Transposition

question

12. Which type of Recombination is used for lambda integration?

answer

12. Site-specific Recombination

question

13. Which type is used for generalized transduction, transformation and conjugation?

answer

13. Homologous

question

14. Which type is used by insertion sequences, transposons, and phage Mu?

answer

14. Transpostion

question

15. How does Site-specific work?

answer

15. Requires very little homology and uses enzymes that recognize apecific sites and recombine them

question

16. What type requires host- or phage-encoded homologous recombination proteins?

answer

16. Homologous Recombination

question

17. What type involves insertion of transposable elements into different hon-homologous sites in the host DNA?

answer

17. Transposition

question

18. What are the 3 regions of the prokaryotic gene?

answer

18. Regulatory Region, Coding Region, Termination Region

question

19. What codes for the protein to begin?

answer

19. Initiator Codon – ATG

question

20. When does the mRNA begin coding?

answer

20. Before the ATG codon

question

21. Where does the ribosome bind?

answer

21. Upstream or ATG

question

22. What region has the most base pairs?

answer

22. Coding region 300-3000bp

question

23. What else is within some genes in the regulatory region?

answer

23. Repressor binding sites, activator binding sites

question

24. What do most isolated genes have?

answer

24. Promoter and terminator

question

25. What is a DNA segment that when transcribed produces a single mRNA which encodes for more than one polypeptide called?

answer

25. Operon

question

26. What is a Gene?

answer

26. A segment of DNA encoding a single polypeptide

question

27. What is a Regulon? Example?

answer

27. Single regulatory protein that affects multiple operons; the arginine biosynthetic regulon

question

28. What is it called when multiple genes and operons are controlled by a single stimulus? Example?

answer

28. Stimulon; heat shock, cold shock

question

29. T/F Transcription and Translation in Prokaryotes is coupled.

answer

29. T

question

30. How does the direction of transcription correspond to the lengths of the mRNA transcripts?

answer

30. The more laden with ribosome the transcript the earlier they were transcribed

question

31. How is Transcription and Translation coupled?

answer

31. Ribosomes bind in succession to the nascent mRNA molecule and begin translation while the mRNA is being transcribed from the DNA. mRNA degradation follows close behind.

question

32. What is the process of Translation of an mRNA?

answer

32. Ribosome recognizes a binding site (rbs) around 6-9 bp upstream of initiation codon (AUG), Translation of gene until Stop codon is reached. At the end of the mRNA will be a transcription terminator.

question

33. Do prokaryotic genes have introns?

answer

33. No – the gene and the polypeptide product are collinear

question

34. T/F many bacterial genes are grouped into multicistronic operons.

answer

34. T

question

35. What does a cistron/gene encode for?

answer

35. Single polypeptide

question

36. What is the difference in Transcription and Translation between Eukaryotes and Prokaryotes?

answer

36. Prokaryotes – coupled, translation begins before the entire mRNA is transcribed; Eukaryotes – the mRNA must leave the nucleus to be translated in cytoplasm

question

37. What does the prokaryotic mRNA lack on its 5’ and 3’ ends that eukaryotic mRNA has?

answer

37. 5’ 7-methyl GTP cap, 3’ poly-A tail

question

38. What are prokaryotic proteins initiated with?

answer

38. N-formyl methionine

question

39. What does N-formylated peptides act as?

answer

39. Chemoattractants for neutrophils and monocytes

question

40. What are mutations?

answer

40. Changes in the DNA sequence, change the genotype, may or may not change the phenotype

question

41. What are the 5 types of Mutations?

answer

41. I. Base substitution mutation; II. Frameshift mutations; III. Large deletions; IV. Large insertions; V. Large inversions or translocations

question

42. What is a transition?

answer

42. Purine a Purine (G aA) Pyrimidine aPyrimidine (Ca T)

question

43. What is a Transversion?

answer

43. Purine to Pyrimidine (G or A a C or T) Pyrimidine to Purine (C or T a G or A)

question

44. What is a missense mutation?

answer

44. Protein function altered by incorporation of a different amino acid

question

45. What is a Nonsense mutation?

answer

45. Stop codon generated

question

46. What is a mutation called that is an insertion of deletion of one or two bases?

answer

46. Frameshift mutations

question

47. What would characterize a Large deletion?

answer

47. hundreds to thousands of contiguous bases are lost, leading to severely defective or undetectable proteins

question

48. What are large insertions caused by?

answer

48. insertion of transposable element

question

49. If large inversions or translocations are not genetically programmed, what can they cause?

answer

49. severe defects in protein function

question

50. What are 2 examples of spontaneous mutations?

answer

50. 1. mistakes made during DNA replication and repair; 2. Mutations caused by natural exposure to mutagens.

question

51. What are some examples of Natural Mutagens?

answer

51. UV light, cosmic rays, heat, transposable elements

question

52. What are some examples of purposeful mutagens?

answer

52. X-rays, UV light, chemical mutagens, transposable elements

question

53. At what frequency to mutations caused by purposeful exposure to mutagens occur?

answer

53. 10-3 to 10-5

question

54. What DNA repair system is highly error-prone?

answer

54. SOS repair system

question

55. What is the frequency of mistakes made during DNA replication and repair?

answer

55. 10-6 to 10-9

question

56. What are 3 regulatory Mechanisms?

answer

56. 1) Change in the DNA sequence; 2) transcriptional regulation; 3) posttranscriptional regulation

question

57. What are used in transcriptional regulation?

answer

57. Activators and Repressors

question

58. What are 3 forms or posttranscriptional regulation?

answer

58. Covalent modification, proteolytic cleavage, binding to host cell proteins

question

59. What is it called when an effector molecule binds a protein altering its ability to interact with its substrate?

answer

59. Allostery

question

60. What is a regulatory protein called that turns ON the genes when bound to DNA?

answer

60. Activator

question

61. What is a repressor?

answer

61. regulatory protein that turns genes OFF when bound to DNA

question

62. What is a chemical called that when bound to the regulatory protein turns genes ON?

answer

62. Inducer

question

63. What is a Negative regulation caused by binding of a chemical to the regulatory protein called?

answer

63. co-repressor

question

64. How are catabolic operons usually regulated?

answer

64. positive regulation, (the default state is off)

question

65. What type of operons are often negatively regulated?

answer

65. Biosynthetic operons (default state is on)

question

66. How is regulation by small molecules accomplished?

answer

66. by the concentration dependence of binding of the small molecules to the regulatory proteins.

question

67. How do bacteria use catabolite repression?

answer

67. distinguish between good and poor carbon sources and repress the lac operon gene until all the glucose is used up.

question

68. How is catabolite repression mediated?

answer

68. concentration of cAMP, inversely related to glucose levels. (Glucose High – cAMP low; Glucose low – cAMP high)

question

69. What regulatory protein is involved in catabolite repression?

answer

69. Cabolite Activator Protein (CAP) (also called CRP – cAMP receptor protein)

question

70. Where does CAP bind and what kind of regulatory protein is it?

answer

70. Promoter region of lac operon; activator protein

question

71. What does CAP interact with?

answer

71. RNA polymerase and turns on transcription

question

72. T/F CAP alone can bind to the promoter DNA.

answer

72. F – Only CAP in a cAMP-CAP complex can bind to DNA.

question

73. What is the monitor of cAMP levels?

answer

73. CAP

question

74. What is the lac operon transcribed from the promoter as?

answer

74. polycistronic mRNA

question

75. How does the absence of the inducer prevent lac mRNA transcription?

answer

75. Lac repressor binds to operator

question

76. What is the inducer of the Lac Operon called?

answer

76. allolactose

question

77. In the presence of allolactose what happens?

answer

77. binds to repressor, causes conformational change that makes the repressor unable to bind to operator DNA

question

78. Once the repressor is inactivated why are only a small number of transcripts made?

answer

78. lac promoter is poor

question

79. What happens in the absence of both glucose and lactose?

answer

79. High cAMP levelsabinds to CAPa cAMP-CAP complex binds to the promoter, BUT no Lactose so no Inducer (allolactos), so repressor stays bound to operator, No Transcription, No lac mRNA

question

80. What happens in the presence of Lactose but the absence of glucose?

answer

80. Lac repressor binds inducer, cAMP binds CAP, cAMP-CAP complex binds promoter causeing high levels of transcription

question

81. What is the Trp Operon?

answer

81. encodes the five enzymes needed for biosynthesis of amino acid tryptophan.

question

82. What is the leader peptide and where is it located?

answer

82. contains 2 tryptophans near its C-terminus; between the operator and the first gene.

question

83. What is the default condition of the Trp Operon?

answer

83. ON, it’s a biosynthetic operon

question

84. What causes the repressor protein to become active and bind the operator?

answer

84. excess tryptophan

question

85. In High concentrations of Trp how is the leader mRNA translated?

answer

85. quickly, preventing the stable 2-3 hairpin, and leading to the formation of the 3-4 hairpin that serves as a terminator.

question

86. What occurs at low concentrations of Trp?

answer

86. ribosomes stall at the 2 trp codons, allowing the 2-3 hairpin to form an anti-terminator structure, allowing transcription to proceed.

question

87. What do hairpin 1-2 and 3-4 cause and why?

answer

87. termination; no protein synthesis

question

88. What do virulence factors do?

answer

88. foster survival and multiplication in the host

question

89. What type of signals do Bordetella pertussis us for virulence gene expression?

answer

89. temperature, SO4, nicotinic acid

question

90. What type of organisms use Iron as a Signal?

answer

90. Corynebacterium diphtheria, E. Coli, Pseudomonas aeruginosa

question

91. How does the Two-Component Regulatory system work?

answer

91. The sensor and transducer are phosphorylated by a signal, the P-Transducer activates transcription

question

92. What is Quorum Sensing?

answer

92. the ability of the cell to sense the cell density

question

93. What do bacterial pathogens use quorum sensing for?

answer

93. to co-ordinate their expression of virulence genes in order to evade the immune response

question

94. What can be used to interfere with quorum sensing?

answer

94. chemical agents

question

95. What is quorum sensing especially important in forming?

answer

95. Biofilms

question

96. What are 3 reasons why Gene Transfer in Bacteria are medically important?

answer

96. 1) spread of antibiotic resistance; 2) exchange of virulence factors; 3) antigenic variation

question

97. T/F Gene transfer is rare.

answer

97. T – varies from 10-2 to 10-6 per cell

question

98. What is Transformation?

answer

98. the transfer of genetic information from one cell to another via naked DNA

question

99. What are some examples of bacteria that can naturally transform?

answer

99. Gram Negative – Campylobacter spp, Haemophilus influenza, Neisseria meningitides Gram Positive – Bacillus subtilis, Clostridium botulinum, Strep. pneumoniae

question

100. What is the ability to bind and take up DNA called?

answer

100. competence

question

101. How is DNA structured during uptake into the recipient cell in natural transformation?

answer

101. fragmented

question

102. What 2 forms of artificial Transformation uptake DNA in an intact form?

answer

102. Induced and Electroporation

question

103. What is an example of Induced transformation?

answer

103. high salt and heat shock for E. Coli

question

104. What happens in Electroporation?

answer

104. cells exposed to short burst of high electric field that transiently permeabilizes the cells and causes them to take up molecules for the surrounding medium

question

105. T/F Competence is involved in Electroporation.

answer

105. F

question

106. What are the steps in the Gram Positive Species Transformation Process?

answer

106. 1) DNA released from cell; 2) DNA binds to cell surface receptor and taken up into the cell, 1 strand is degraded; 3) single strand invades its homologous region and displaces one original strand; 4) heteroduplex is replicated, producing 1 tranformant and one unaltered recipient genome; 5) Close genetic markers can be transformed together on a single DNA fragment

question

107. What are the 2 exceptions in Gram-Negative Transformation?

answer

107. 1) DNA binding requires specific sequences in the double-stranded DNA in order to bind the receptor. 2) DNA is taken up in a double-stranded form in a membrane vesicle.

question

108. What is the membrane vesicle called?

answer

108. transformasome

question

109. What involves the direct transfer of genetic information form one cell to another via cell to cell contact?

answer

109. Conjugation

question

110. What does conjugation require?

answer

110. cell to cell contact and specific surface proteins

question

111. T/F Conjugation is not DNase resistant.

answer

111. F – it is DNase resistant

question

112. How is the ability to promote conjugation usually endoded?

answer

112. by a plasmid in the donor cell

question

113. What are plasmids?

answer

113. covalently closed, circular, supercoiled DNA molecules that replicate autonomously

question

114. How are plasmids inherited?

answer

114. stably in an extrachromosomal state

question

115. Are plasmids essential?

answer

115. No, they are “extra DNA” sometimes lost

question

116. What are a few types of genes that plasmids can carry?

answer

116. antibiotic resistance, toxin production, metal ion resistance, virulence factors, bacteriocin production, etc.

question

117. What is the Incompatibility property of plasmids?

answer

117. prevents 2 related plasmids from stably replicating in the same cell

question

118. What prevents entry of a plasmid into a cell that already had a closely related plasmid?

answer

118. Surface exclusion

question

119. Are unrelated plasmids affect by Incompatibility and Surface exclusion?

answer

119. No

question

120. What is the Host Range?

answer

120. host in which a plasmid can replicate

question

121. How is the copy number determined?

answer

121. by the plasmid replication system, no the plasmid size

question

122. T/F – Often small plasmids have a high copy number whereas large plasmids usually have a low copy number.

answer

122. T

question

123. What type of plasmids have the ability to promote their own transfer from one cell to another?

answer

123. Conjugative plasmids

question

124. Are Non-conjugative plasmids able to promote their own transfer?

answer

124. No

question

125. What are the 2 types of non-conjugative plasmids?

answer

125. Mobilizable and Non-mobilizable

question

126. How are mobilizable plasmids transferred?

answer

126. can’t transfer themselves but can be mobilized to transfer by another conjugative plasmid in the same cell.

question

127. How are Mobilizable plasmids classified?

answer

127. oriT+

question

128. T/F Non-mobilizable plasmids can’t transfer under any condition.

answer

128. T – they are oriT (origin of transfer) defective

question

129. What confers the ability of F factor of E. Coli to integrate into the host chromosome?

answer

129. IS sequences

question

130. What type of cells are good recipients for DNA transfer by conjugation because they have no F factor?

answer

130. F-

question

131. What type of cells have an extrachromosomal F factor?

answer

131. F+

question

132. Which type of cells have the F factor integrated into the chromosome?

answer

132. Hfr

question

133. How is the F Factor in the F’ cell?

answer

133. the extrachromosomal F factor also carries some chromosomal genes incorporated during aberrant excision of an integrated plasmid

question

134. What are the steps in Transfer of an F Plasmid by conjugation?

answer

134. 1) F pilus of donor cell contact recipient cell, pulls it in; 2) conjugation bridge formed, plasmid DNA nicked at oriT; 3) DNA replicated by rolling circle replication, 5’ end transferred through conjugation bridge, complementary strand made; 4) complete transferred plasmid circularizes and become stable; 5) Conjugation bridge breaks.

question

135. What are the steps of Chromosomal DNA transfer by an Hfr?

answer

135. 1) Hfr cell contacts recipient (F-) cell with F pilus, forms conjugation bridge; 2) Nicking oriT, rolling circle replication, 5’ end transferred; 3) conjugation bridge breaks before circularization sequence is transferred; 4) Transferred strand find homologue in recipient chromosome and recombines into it.

question

136. How does Conjugation occur in Gram-Positive bacteria?

answer

136. recipient cells make small peptide pheromones, causing donor cells to make adhesions and cells clump, conjugation bridges form.

question

137. T/F pheromones are specific for plasmids.

answer

137. T

question

138. What can the IS element serve as?

answer

138. a region of homology for recombination into the host chromosome

question

139. How can homologous recombination lead to excision or inversion of the intervening DNA?

answer

139. depending on the relative IS orientation

question

140. How does Amplification of Resistance work?

answer

140. Increased number of drug resistance genes integrated into the cell confer resistance to a higher concentration of antibiotics

question

141. What are integrons?

answer

141. discrete DNA elements that carry promoterless antibiotic resistance genes

question

142. How do integrons integrate?

answer

142. specific sites and do not encode a transposase

question

143. More multi-drug resistant plasmids may be generated by what?

answer

143. Integrons

question

144. What are bacteriophages?

answer

144. viruses that infect bacteria

question

145. How are phages organized?

answer

145. particles are composed of a single molecule of nucleic acid which is protected by a protein coat.

question

146. What are the 2 types of Lifestyles phages can take?

answer

146. Virulent and Temperate

question

147. What lifestyle results in the production of more phage particles through lytic development?

answer

147. Virulent

question

148. What 2 outcomes can result from a Temperate Phage?

answer

148. 1) lytic development and progeny phage production. 2) formation of lysogen containing a repressed prophage.

question

149. What is used by phages for adsorbing to their host cells?

answer

149. tails

question

150. What are the steps in Lytic Development?

answer

150. 1) Adsorption; 2) Injection of DNA; 3) Transcription of phage DNA; 4) Phage proteins made, phage DNA replicated, conversion of bacterium to phage factory; 5) “Factory” produces Phage structures; 6) DNA packaged into phage; 7) Lysis … Repeat

question

151. How can phages be detected in an agar plate?

answer

151. formation of plaque

question

152. What are the steps in Lysogen Formation with Integration?

answer

152. 1) Phage DNA injected into bacterium; 2) Lytic functions turned off in phage mRNA synthesis by Repressor; 3) Phage DNA molecule inserted into chromosome of bacterium by Integrase protein; 4) bacterium grows and divides with phage genes as part of bacterial chromosome

question

153. T/F – Lysogen Formation with Replication as a Plasmid integrates the phage DNA into the bacterial DNA.

answer

153. F – There is no integrase or integration, the phage DNA replicates at a low level as a plasmid

question

154. How does Induction of an integrated prophage or a plasmid prophage take place?

answer

154. destruction of the phage repressor protein

question

155. T/F – All Lysogens are immune to superinfection

answer

155. T

question

156. What can lysogenic conversion do?

answer

156. alter cell wall properties and provide new phage resistances

question

157. What phage of C. diphtheria carries the tox gene which encodes diphtheria toxin?

answer

157. temperate phage ?

question

158. What phage encodes for SPE’s responsible for scarlet fever?

answer

158. Phage T12

question

159. What phage encodes a Shiga-like toxin?

answer

159. Phage H19B

question

160. T/F – Infection by a non-toxigenic strain of C. botulinum with a phage that encodes a toxin can convert the strain to a virulent strain that produces the toxin.

answer

160. T

question

161. What is Transduction?

answer

161. the transfer of genetic material by a phage particle

question

162. What are the 2 types of Transduction?

answer

162. Generalized and Specialized

question

163. Which type of Transduction occurs by mistaken packaging of a piece of host DNA into a phage particle instead of a phage DNA?

answer

163. Generalized

question

164. How does Specialized Transduction occur?

answer

164. aberrant excision of a prophage leading to incorporation of a small piece of host DNA into the phage genome

question

165. What is abortive transduction?

answer

165. formation of microcolonies instead of normal-sized colonies because the transduced DNA circularizes and only passed to 1 of 2 daughter cells.

question

166. What does Excision of Lambda DNA require?

answer

166. integrase and XIS proteins

question

167. What is Lambda integration catalyzed by?

answer

167. ? integrase protein

question

168. What are ?dgal phages defective for?

answer

168. growth and plaque formation

question

169. What is provided to help the phages with missing function grow?

answer

169. helper phage

question

170. What are High Frequency Transducing lysate (HFT)?

answer

170. a transductant that arises by lysogenization with both a transducing phage and a normal helper phage

question

171. What is the size of DNA transferred by Transduction?

answer

171. 1-2% of the chromosome

question

172. What transfers medium sized pieces of DNA, 5-10% of chromosome?

answer

172. Transformation

question

173. How big are pieces of DNA that are transferred with conjugation?

answer

173. 25-50% of chromosome

question

174. What is a Transposable element?

answer

174. discrete segments of DNA that move from one site to another in a genome without a requirement for DNA sequence homology

question

175. What is Transposition catalyzed by?

answer

175. transposase enzyme

question

176. What do all transposable elements (TE) have?

answer

176. short (15-30bp) inverted repeats

question

177. What are a type of TE with short inverted repeats at ends and no detectable phenotypes?

answer

177. Insertion sequences, IS

question

178. What are Type 1 composite transposons?

answer

178. large elements with long repeats at the ends and unique DNA in the middle, usually antibiotic resistance

question

179. Which type of TE has ends that cannot transpose independently?

answer

179. Tn3-like transposons

question

180. What type of TE has the ability to cause mutation by insertion into host genes?

answer

180. Mu bacteriophage

question

181. What part of the TE binds the transposase?

answer

181. short inverted repeats at the ends

question

182. How can insertion into a gene disrupt the gene function?

answer

182. can eliminate function of downstream genes by polarity

question

183. How does simple transposition work?

answer

183. Tn from replicon 1 adds on to replicon 2

question

184. What happens in Replicative transposition?

answer

184. cointegration

question

185. How does Replicative transposition and resolution work?

answer

185. R1 and R2 add together and replicate and cointegrate, then separate back down to separate R1 and R2 each with Tn.

question

186. T/F – conjugative transposons can transfer between Gram+ and Gram- bacterial species.

answer

186. T

question

187. What are some examples of Diagnostic Methods?

answer

187. Direct Examination, Culture, Antibody Detection, Detection of Microbial Components or Metabolites, Genome Detection

question

188. How can a direct specimen be taken?

answer

188. when pathogen is located in an otherwise sterile site, abscess, collected surgically or by needle aspiration

question

189. What is a specimen called that is in a sterile site but must pass through a site containing normal flora to be collected?

answer

189. Indirect Sample

question

190. How is a Sample taken from a site with normal flora?

answer

190. Sample collected is a mixture, normal flora are inhibited under growth conditions for analysis.

question

191. What are a few guidelines for Specimen Selection, Collection, and Transport?

answer

191. Select from active infection, minimize contamination, collect before antimicrobial therapy, minimize time from collection to assay…. etc.

question

192. How does an Agglutination Assay work?

answer

192. Antibody is bound by its Fc receptor end to the protein A on the surface of dead Staph. A. Visible agglutination is produced when these particles combine with a soluble antigen or another particulate antigen.

question

193. How does Direct Immunofluorescence work?

answer

193. 1) Acetone-fixed cells on slide; 2) Add fluorescein-conjugated antiserum and incubate; 3) Wash unattached antibody; 4) Exam for fluorescence under UV illumination

question

194. What is different about Indirect Immunofluorescence?

answer

194. Rabbit antibody added first which is pathogen specific, then fluorescein-labeled goat anti-rabbit antibody is added, then viewed under UV light.

question

195. What type of enzymes are used in Enzyme-linked Assays?

answer

195. Horseradish peroxidase, Alkaline Phosphatase, Beta-galactosidase

question

196. How are ELISA Assays reported?

answer

196. titer reported is the highest serum dilution that still gives a detectable Ag-Ab reaction based on the color observed.

question

197. What is the Western Blot used for in detection of Anti-HIV Ab in serum?

answer

197. Distiguishes false positive ELISA vs True positive

question

198. Why are DNA Probes convenient for detection?

answer

198. Probe is pathogen specific and commercially available.

question

199. What are some advantages of PCR?

answer

199. more sensitive than direct hybridization, need very small amount of DNA in specimen, very fast

question

200. What are some disadvantages of PCR?

answer

200. Expense, false positives, false negatives

question

201. When should PCR be used?

answer

201. for pathogens with no existing test, poor tests, or diseases with low antigen and antibody production

question

202. What are some examples of pathogens that PCR is used to detect?

answer

202. hepatitis B, Chlamydia trachomatis, Neisseria gonorrhoeae, HIV, Lyme disease

question

203. What does Amplicon Detection by Real-Time PCR use?

answer

203. DNA intercalating dyes or fluorogenic DNA probes

question

204. How is contamination reduced in Amplicon Detection by R-T PCR?

answer

204. Amplification and detection are done simultaneously in a closed system.

question

205. Order the following from fastest to slowest time it takes for results:

answer

205. C, F, D, A, E, B

question

206. What is a virus?

answer

206. Obligate intracellular parasites that replicate by self-assembly of individual components rather than by binary fission.

question

207. Can Viruses make energy or proteins by themselves?

answer

207. No

question

208. T/F – viruses contain a genome with RNA and DNA.

answer

208. F – contain a genome of limited size that is either RNA or DNA, never both.

question

209. How are viruses classified?

answer

209. 1. Size; 2. morphology; 3. type of genome; 4. mechanism of replication. (physical and biochemical characteristics)

question

210. How can virus genomes be structured?

answer

210. 1. circular or linear ss RNA

question

211. What is the protein shell that packages the virus genome?

answer

211. capsid

question

212. What 3 forms can capsids be in?

answer

212. icosahedral (spherical) , helical, complex

question

213. Capsids are the result of self-assembly of what?

answer

213. virally-encoded capsomeres

question

214. How is the shape of the capsid dictated?

answer

214. by the capsomeres that self-assemble, not the shape of the genome.

question

215. What makes up a nucleocapsid?

answer

215. genome + capsid

question

216. Why are enveloped viruses less stable than naked viruses?

answer

216. a. more susceptible to drying

question

217. How do enveloped viruses spread?

answer

217. large droplets, secretions, organ transplants, blood transfusions.

question

218. How many families of DNA viruses are there? RNA viruses?

answer

218. 6; 14

question

219. What are the major steps in viral replication?

answer

219. 1. attachment

question

220. What are the 6 viral cytopathogenesis?

answer

220. 1. Inhibition of cellular protein synthesis

question

221. Can the +RNA virus genome function as mRNA?

answer

221. Yes – and is immediately translated by cellular ribosomes

question

222. How are –RNA virus genomes used?

answer

222. must be used as a template to transcribe a +RNA strand

question

223. How do retroviruses function?

answer

223. carry a RNA-dependent DNA polymerase (reverse transcriptase), +RNA genome is reverse transcribed into dsDNA and integrated into host genome

question

224. How are DNA virus genomes transcribed?

answer

224. By host DNA-dependent RNA polymerase

question

225. What do viruses use to redirect host polymnerases to viral genes and away from cellular genes?

answer

225. specific transcription factors

question

226. What do larger viruses depend of for viral genome replication?

answer

226. virally-encoded DNA-dependent DNA polymerases

question

227. Do smaller viruses need this?

answer

227. No, they use host DNA polymerase

question

228. How are plaques formed?

answer

228. virus infected cells are lysed and leave a “hole” in a confluent monolayer

question

229. What is a lysate?

answer

229. the suspension of virions in culture medium that results from unrestricted growth of the virus on a cell monolayer

question

230. T/F – all virus particles produced in a lysate are infectious.

answer

230. F – particle-to-pfu ratio measure the number of physical particles compared to the number of infectious virions

question

231. What do Plaque assays measure?

answer

231. the number of infectious virions in a given volume of lysate.

question

232. What is the Multiplicity of Infection (MOI)?

answer

232. the ratio of the number of infectious particles to the number of target cells to be infected.

question

233. What MOI is needed to ensure that all cells are infected?

answer

233. between 5-10

question

234. What corresponds to the eclipse period of the single-cycle growth curve?

answer

234. post-penetration phase until virus can be detected intracellulary; corresponds to uncoating, early transcription, and genome replication steps;

question

235. When does the eclipse period end?

answer

235. a Virus assembly

question

236. When does the latent period take place?

answer

236. post-penetration phase until virus can be detected extracellularly

question

237. What does the latent period correspond to?

answer

237. uncoating, early transcription, genome replication, virus assemble, and release

question

238. T/F – the latent period includes the eclipse period.

answer

238. T

question

239. Why do viral mutation occur at high frequencies?

answer

239. large number of genome copies produced in every infected cell, and polymerase errors

question

240. What step of viral genetics involves exchange of proteins?

answer

240. Complementation

question

241. What happens in Recombination?

answer

241. An exchange of genetic material on the same segment of genome.

question

242. Does recombination occur with both DNA and RNA?

answer

242. DNA – yes occurs frequently

question

243. What is the process called that is an exchange of genetic material on different segments of genome?

answer

243. Reassortment

question

244. What are some things to consider about virus-host interactions?

answer

244. route of transmission, secondary spread, incubation period, acute vs. persistent infection, control

question

245. What is the most common rout of infection?

answer

245. inhalation

question

246. What are 2 ways viruses are spread?

answer

246. release of virus from infected cell or syncytia formation

question

247. What is syncytia formation?

answer

247. enveloped viruses can fuse an infected cell with uninfected cells to directly spread to surrounding cells

question

248. What is viremia?

answer

248. presence of virions in blood

question

249. What is the minimum incubation period for viruses that require secondary spread?

answer

249. 12-14 days

question

250. T/F – patients can be infection during the incubation period.

answer

250. T

question

251. What phase of an infection is the symptomatic phase?

answer

251. acute phase

question

252. What are the 3 froms of persistent infection?

answer

252. Chronic, latent, transforming

question

253. What is an example of a latent virus? transforming virus?

answer

253. herpes; HPV, HIV

question

254. What is the first defense in nonspecific immune response?

answer

254. natural killer cells and IFN

question

255. What are 3 types of antivirals available?

answer

255. vaccines, immune globulin, drugs

question

256. What are the 3 basic types of viral vaccines?

answer

256. live, attenuated virus; killed virus; subunit (recombinant DNA)

question

257. What is the challenge of antiviral drugs?

answer

257. viruses are parasites and use much of our own cellular processes, Drugs toxic to Viruses can be toxic to us.

question

258. What drug inhibits uncoating of picornaviruses?

answer

258. Disoxaril

question

259. What drug inhibits uncoating of influenza A and how does it work?

answer

259. amantadine and rimantadine; inhibits a viral ion channel

question

260. What does IFN-alpha inhibit in hepatitis B and C and HPV?

answer

260. transcription and translation

question

261. How is translation of CMV mRNA inhibited?

answer

261. a specific antisense RNA

question

262. What do the majority of antivirals target and what are they composed of?

answer

262. DNA replication; nucleotide analogs that inhibit viral DNA polymerases or prevent chain elongation

question

263. How do protease inhibitors work?

answer

263. prevent polyprotein cleavage and virus assembly by acting as alternative substrates

question

264. What does ribavirin do?

answer

264. inhibits nucleoside biosynthesis and as a result inhibits mRNA cap formation and inhibits some RNA polymerases.

question

265. What is ribavirin used for?

answer

265. Hepatitis C, Flu and respiratory syncytial virus

question

266. What inhibits flu A and B neuraminidase?

answer

266. Relenza and Tamiflu

question

267. What do inhibitor cocktails do?

answer

267. decrease the chances of encountering a resistant strain

question

268. T/F – Combination therapies appear to be synergistic.

answer

268. T

Microbiology Assessment 2 – Flashcards

Unlock all answers in this set

Haven't found what you were looking for?

Search for samples, answers to your questions and flashcards