test #5 Flashcards
which of the following features of the trp operon is likely least essential to the process of attenuation?
a. transcription and translation of the leader sequence occur simultaneously
b. the order of the structural genes (EDCBA)
c. Trp codons near the beginning of the leader sequence
d. ability of sequences within the leader mRNA to pair with one another
b
what mRNA is expressed at elevated growth temperature, leading to transcription of heat shock genes?
a. sigma70
b. Cro
c. IS10
d. rpoH
e. glmS
d. rpoH
to use RFLP analysis to detect a SNP, the SNP must
a. occur in heterozygous form
b. occur within a restriction enzyme recognition sequence
c. be present in at least 11% of the population
d. cause disease
e. occur within a sequence of a transposon
b
which of the following occurs as a result of an abundance of tryptophan in E. coli?
a. leader sequence isn’t transcribed
b. 5 trp genes (A-E) are transcribed, not translated
c. 5 trp genes (A-E) aren’t transcribed
d. leader sequence is duplicated
e. stalling of the ribosome at trp codons in the leader sequence
c
which of the following statements regarding NER/BER is true?
a. both can be activated by exposure to light
b. only NER involves creation of AP site
c. both NER/BER involve removal of one or more damaged bases by a nuclease
d. both NER/BER involve the creation of an AP site
e. only NER involves the action of DNA ligase to seal nicks
c
what type of damage results in an apurinic site?
a. breaking covalent bond at the 1’ C of deoxyribose in a purine
b. replacing hydrogen at 5’ C with CH3
c. breaking covalent bond at 4’ C of deoxyribose in a pyrimidine
d. breaking covalent bond at 5’ C of deoxyribose in a purine
a
propose of the Ames test
to test the mutagenic effects of chemicals
__________ is an inhibitor of apoptosis in healthy cells that can be directly inhibited by _______ in cells with DNA damage
BCL2, BAX
in bacterial transformation lab, which of the following is most directly responsible for allowing bacteria to grow int he presence of Ampicillin
bla gene
if UGG codons in Region 1 of trpL were changed to AGG codons, what effect would this have on expression of the trp operon?
operon would be regulated by arginine levels; high levels of arginine would attenuate expression of trp genes
CAP binding site in the lac promoter is the location of + regulation of gene expression for the operon. how doe the binding exert a positive effect?
a. alters structure of promoter and allows RNA polymerase to bind to it
b. CAP interacts with Tup-1 to prevent transcription in presence of glucose
c. complex triggers formation of DNA loop, which prevents binding of repressor protein
d. complex unbends DNA loop, allowing binding of RNA pol
e. complex prevents binding of repressor protein
a
which transposable element in bacteria lacks IS sequences?
non-composite transposons
in mismatch repair in E. coli, the MutH/L/S system uses nearby 5’GATC3’ sequences. what is a common modification on this sequence?
methylation on the adenine
if non-trinucleotide repeat expansions were present in the coding region of a gene, which type of mutation would you expect to be the most likely?
frameshift
which is a consequence of mutational inactivation of both p53 alleles in a cell?
a. programmed cell death
b. reduction of p21 synthesis
c. decreased rates of certain types of cancer
d. relative instability of the non-functional protein
e. reduction in kinase activity of the cyclin-cdk complex
b
which of the following spontaneous mutations alters DNA structure/sequence and generally results from strand slippage?
expansion of trinucleotide repeat sequences
which of the following conditions would induce the lytic cycle in Lambda phage infected E. coli cells?
a. mutating the N protein in a way that prevents its binding to DNA
b. higher levels of cI than cro in the cell
c. poorly growing bacterial host population
d. mutating the cI gene in a way that causes its protein product to bind to DNA
e. large number of co-infecting phage
a
what would happen to the expression of the lac operon if you mutated the enzyme adenylate cyclase in a way that caused it to make cAMP constitutively?
it would be expressed at high levels in response to lactose in the presence of absence of glucose
translation of the third person genes in E. coli occurs when…
a. high TPP concentration leads to formation of anti termination stem loop
b. low TPP concentrations leads to formation of anti termination stem loop
c. low TPP leads to formation of riboswitch to initiate transcription
d. high TPP initiates riboswitch that leads to intrinsic termination
e. low TPP leads to formation of a Shine-Dalgarno antisequestor stem loop
e
what type of DNA damage is repaired by the enzyme photolyase?
thymine dimers
___________ are molecules that have the same composition and general arrangement but a slight difference in bonding/placement of a hydrogen
tautomers
2 types of double stranded break repair
- non-homologous end joining
- synthesis dependent strand annealing (homology direct repair)
proteins needed for NHEJ
Ku70, Ku80, PKcs
proteins needed for SDSA
Rad51
