ASCP Exam Questions ASCP Exam Questions, Exams of Biology

Download ASCP Exam Questions ASCP Exam Questions and more Exams Biology in PDF only on Docsity! ASCP Exam Questions Which is required to generate cDNA A. DNA polymerase B. RNase H C. Restriction Enzyme D. Helicase -         B What is the function of Taq Polymerase -         recognize dsDNA You have a 50 μL primer stock at 9pM/μl and want dilute the stock to 900nM. How much stock should you add(what is the dilution factor) -         2 What gene causes hypersensitivity to Irinotecan? -         UGT1A Which allele causes hypersensitivity to Carbamazepine? -         HLA-b*1502 What gives MLPA its specificity -         Stuffer Sequence How is copy number determined? -         MLPA What is the gene that cause resistance to Vancomycin -         vanA Which assay is FISH best used for -         Prader Willi RNA polymerase II: where is it and what does it do -         Eukaryotic: It catalyzes the transcription of DNA to synthesize precursors of mRNA and most snRNA and microRNA. (transcribes mRNA) Hazard that is blue and is level 4 what does it mean -         big health hazard Dr calls wanting test results but results have not been signed out by a medical director what do you do -         don't give out the result until it has been signed out my the MD What trinucleotide repeat is involved in Fragile X? -         CGG In Fragile X, what is considered a full mutation expansion? -         200+ What method is used to detect Fragile X? -         Southern blot (now PCR /mPCR) Which gene is the largest and has deletions/duplications as the most common mutation types -         DMD Which HCV geneotype(s) has/have the best prognosis -         Genotypes 2 &3 Positive attributes of bDNA -         Can be used for both DNA and RNA What type of primer set is best? -         forward primer should complement DNA strand and reverse primer should mirror and inversely complement the forward primer What are some things that stabilize RNA? -         Inactivated and minimizing exposure to environmental/endogenous RNases mRNA: 5'cap What is the concentration of DNA with an OD of 2.0 -         100 μg/mL Given the following data what can quantifiably be said about DNA when 260 = 1.4 and 280 = 1.1 -         There is 70ng of pure DNA Sample is contaminated with proteins and phenols What is the equation for PCR efficiency -         (1+Σ)^n You have a gel where the positive control worked, the negative control worked, patient 1 had a double band, patient 2 was positive, and patient 3 had no bands. What would you do? -         repeat patient 3 How do you detect for methylation -         Bisulfate sequencing MSI (Micro-Satellite Instability) tests for what? -         Mismatch Repair Genes What is it called when 2 double stands of DNA is covalently linked by the 5' to 3' ends -         ligation Capillary Electrophoresis uses what -         Polyacrylimide In RFLP wildtype shows 2 bands and a homozygous mutation shows 1 band. What does a heterozygous mutation look like -         3 bands You have two primers with Tm's 40˚ and 51˚. How do you make them work -         add bases to the primer with the lower Tm* You have a fragment 150-300 bp How much agarose do you use -         3% Denaturing HPLC detects what -         SNPs (also base substitutions, small deletions, and insertions) What is the conformation of DNA in its natural state -         bDNA right-handed helix Most common CF mutation -         3 nucleotide deletion (F508del) Which Herpes virus can lead to PTLD (post-transplant lymphoproliferative disorder) - CMV - HSV - EV - EBV -         EBV RT-PCR detects a gene fusion in the positive, negative and the patient sample what should be done - Repeat RT-PCR - Repeat extraction and RT-PCR - Report out - Perform Southern Blot -         Repeat RT-PCR What is the equation for PPV(positive predictive value) -         PPV=TP/(TP+FP) (#true positives)/(# true positives + # false positives) What can you expect from a multiplex PCR -         you will need to increase the amount of magnesium Translation t(14, 18) -         Follicular Lymphoma DNA Methylation will result in which of the following: - inhibition of transcription - inhibition of translation - gene mutation -         inhibition of transcription (protein inactivation) Real-Time PCR is better as a quantitative then conventional tests based on which of the following?: - Gives you greater dynamic range - Can monitor each cycle better - Can use CT to determine results -         Can use CT to determine results For PCR, I get (many) longer unspecific products. What can I do? -         Decrease annealing time Increase annealing temperature Decrease extension time Decrease extension temperature to 62-68º C Increase KCl (buffer) concentration to 1.2x-2x, but keep MgCl2 concentration at 1.5-2mM. Increase MgCl2 concentration up to 3-4.5 mM but keep dNTP concentration constant. Take less primer Take less DNA template Take less Taq polymerase If none of the above works: check the primer for repetitive sequences (BLAST align the sequence with the databases) and change the primer(s) Combine some/all of the above For PCR, I get (many) shorter unspecific products. What can I do? -         Increase annealing temperature Increase annealing time Increase extension time Increase extension temperature to 74-78º C Decrease KCl (buffer) concentration to 0.7-0.8x, but keep MgCl2 concentration at 1.5-2mM Increase MgCl2 concentration up to 3-4.5 mM but keep dNTP concentration constant Take less primer Take less DNA template Take less Taq polymerase If none of the above works: check the primer for repetitive sequences (BLAST align the sequence with the databases) and change the primer(s) Combine some/all of the above My PCR reaction was working before, but now I am not getting any product. What is a possible explanation and what can I do? -         Make sure all PCR ingredients are taken in the reaction (buffer, template, Taq, etc) Change the dNTP solution (very sensitive to cycles of thawing and freezing, especially in multiplex PCR) If you just bought new primers, check for their reliability (bad primer synthesis ?) Increase primer amount Increase template amount Decrease annealing temperature by 6-10º C and check if you get any product. If you don't, check all your PCR ingredients. If you do get products (including unspecific ones) reaction conditions as described above. Combine some/all of the above My PCR product is weak. Is there a way to increase the yield? -         Gradually decrease the annealing temperature to the lowest possible. Increase the amount of PCR primer Increase the amount of DNA template Increase the amount of Taq polymerase Change buffer (KCl) concentration (higher if product is lower than 1000bp or lower if product is higher than 1000bp) Add adjuvants. Best, use BSA (0.1 to 0.8 µg/µL final concentration). You can also try 5% (v/v, final concentration) DMSO or glycerol. Check primer sequences for mismatches and/or increase the primer length by 5 nucleotides Combine some/all of the above My two primers have very different melting temperatures (Tm) but I cannot change their locus. What can I do to improve PCR amplification? -         An easy solution is to increase the length of the primer with low Tm. If you need to keep the size of the product constant, add a few bases at the 3' end. If size is not a concern, add a few bases at either the 3' or the 5' end of that primer. I have a number of primer pairs I would like to use together. Can I run a multiplex PCR with them?. How? -         Very likely, yes. 4 .Taq polymerase concentration was too low in this PCR reaction -         There was obvious contamination in this PCR reaction If you had multiplex PCR with 2 probes with melting temps of 41 degree and 53 deg and couldn't change target sequence how can you adjust reaction for higher yield? -         increase the length of the probe added bases to the primer with the lower melting temp What is one characteristic of mitochondria DNA? -         NA molecule of approximately 16.5 kb What is Fetal DNA in maternal plasma useful for? -         prenatal investigation of hemophilia A What mediates DNA transcription -         RNA polymerase II How many pairs of chromosomes are in normal diploid human cells -         23 What are examples of patient identifiers? -         patient name, date of birth, SSN, MRN A hemolyzed sample of blood arrives in a molecular diagnostic laboratory for genetic testing. How should the hemolyzed sample be handled? -         Extract the sample with alternative or additional extraction procedures In contrast to liquid-phase DNA extraction methods, protocols based on solid phase are generally: -         less adaptable to extraction of large DNA quantities or large sample volumes What are 4 examples of target amplification techniques? -         PCR, ligase chain reaction, transcription mediated amplification. strand displacement amplification What are 4 key characteristics of fluorescent melting analysis of PCR products? -         -identifies products by their Tm rather than their size -can genotype single base changes in human DNA without probes - can be performed with dyes that stain dsDNA - can be used to verify the identity of PCR product What is an example of signal amplification -         branch-chained amplification What are four things that should be included in a result report? -         1. gene locus 2. disease-causing variants (mutations) tested 3. genotype-phenotype correlations 4. analytic sensitivity and specificity When is correlating molecular results with cytogenetic evaluation useful? -         for translocation testing such as Bcr./abl in malignancies What should ideally occur when studying diagnostic accuracy of a test? -         all patients undergo the index test and are evaluated using a reference standard A 49-year-old younger brother of your patient has been given a diagnosis of HH. DNA testing revealed homozygosity for the C282Y allele. For this reason, you patient requested DNA testing. Homozygosity for the C282Y allele was observed. Your patient has no clinical findings associated with hemochromatosis. Explain. -         Incomplete penetrance. What are key characteristics of DNA linkage studies? -         -they are useful for large genes when no common mutations exist - they require participation from multiple family members - they rely upon polymorphic DNA markers in close proximity to the disease gene - they can yield erroneous results as a result of genetic recombination In which of the following diseases is homozygosity for two mutant alleles not associated with a more severe clinical phenotype: -achondroplasia -charcot-marie-tooth -huntington -thrombophilia -         huntington Expansion of the CGG repeats in an FMR1 premutation allele to a full mutation allele: a. occurs during DNA replication b. is less likely to occur with a CGG repeat length of 79 as compared with 59 c. is dependent on the sex of the fetus d. is more likely to occur during male gametogenesis. -         a When monitoring HIV-1 infected patients with viral-load assays, what change in viral load represents a biologically relevant change in viral replicatione -         0.5log(10) (threefold) The current FDA-cleared HIV-1 genotyping assays detect mutations that confer resistance to all of the following classes of drugs EXCEPT: a. nucleoside reverse transcriptase inhibitors b. nonnucleoside reverse transcriptase inhibitors c. protease inhibitors d. fusion inhibitors -         d. fusion inhibitors What decrease in HCV viral load is needed after 12 weeks of therapy to predict a treatment response? -         2.0log(10) What is one limitation of pharmacogenetic testing? -         cannot identify drug-drug interactions Results describing the phenotype or genotype or TMPT are useful for dosing what drug? -         azathioprine What does the interpretation of CYP2D6 genotyping results depend on? -         - how the CYP2D6 variant(s) detected by the assay affect enzyme function - the presence/absence of gene duplications - the specific variants detected by the genotyping assay - the number of variant alleles detected Malignant tumors arising in tissues of epithelial origin are known as what? -         carcinomas All of the following are tumor suppressor genes EXCEPT: a. p53 b. Rb c. p16/INK4A/CDKN2 d. k-ras e. menin -         d. k-ras clonal antigen receptor gene rearrangements: a. are characteristic of malignant lymphoma b. can be detected by PCR c. can be detected by southern blot hybridization analysis d. all of the above e. none of the above -         d. all of the above What is synovial sacroma? -         -a rare soft tissue neoplasm - has characteristic translocations -is characterized by the t(X; 18) abberation - has characteristic fusions that can be detected by RT-PCR Structural abnormalities affecting genes encoding proteins involved in which of the following processes are frequently identified in human cancers? What are you worries about is plasma is spun down from 7 say old whole blood in regards to CMV viral loads? -         Possible PCR inhibition from hemolysis of RBCs What is the Methicillin resistance mechanism(such as in MRSA with the mecA gene)? -         Enables cell wall synthesis to continue in the presence of antibiotics In real time PCR curves, where is the crossing threshold measured? -         Exponential phase What is the advantage of real-time PCR with quantitative assays over some other methods? -         can get exact CT and then use a std. curve to quantify What translocation causes acute promyeloid luekemia? -         t(15;17) PCR sample with failed internal control but is positive for the target, what should the technologist do? -         check to make sure controls on run passed, then sign out. What structure is responsible for protein synthesis? -         ribosome Which PCR requires an additional step to verify specificity (such as sequencing)? -         PCR/SYBr GReen Which sample would be most appropriate for NoroPCR? -         Stool Sample that has been refrigerated for 3 days??> Which leukemia is associated with the FLT gene? -         AML The polymerization of acrylamide uses what? -         TEMED and ammonium persulfate What structure protects the mRNA from degradation? -         5'cap Every time the chromosome is copied it would become shorter if not for what enzyme? -         telomere transferase How many SNPs in the human genome -         Average occurance: once every 300 nucleotides --> 10 million total Which polymerase is a primase and is associated with the lagging strand? -         Polymerase alpha You received a 9ng DNA sample and have to make 50ul dilution of this sample at 900pg. How many ul of stock do you need?. -         Convert 9ng to pg 1ng = 1000pg, so 9ng is equal to 9000pg V1 (amt stock) = V2C2 9000pg x ?=50 ul x 900pg answer is 5 What type of chromatin is most likely to be transcriptionally active? -         euchromatin which type of HCV is more difficult to treat with IFN and protease? -         1a Storage conditions for RNA > 6 months -         DEPC at -70C or ethanol -70C what is the effect of formamide? -         lowers Tm by disrupting H bonds Differentiate between tumor cells found in acute and chronic leukemias -         Acute: immature cells with limited differentiation Chronic: mature & differential What neoplasms are found in lymphomas (what are common precursors for lymphoid neoplasms)? -         neoplasms of B, T, NK lymphocytes precursor= mature B, T, NK cells What property of DNA in lymphocytes allows for clonality testing? -         B lymphocytes: change the rearrangement of DNA in genes that code for immunoglobulins (Ig) T lymphocytes: rearrange segments of genes that code for antigen recognizing proteins (T-cell receptors) What is the Ig gene rearrangement process susceptible to? What is the underlying consequence? -         susceptible to: abnormal translocation of genes from other parts of the genome into the Ig gene. The abnormally regulated expression (deregulation) of these "foreign" genes underlies the development of lymphoid neoplasia How do chromosomal translocations cause lymphomas? -         dysregulated expression of structurally normal oncogenes. Many involve IgH locus on chromosome 14 (mistakes during V-D-J rearrangement, early events in lymphomagenesis) What is the most frequently employed technique for detection of the chimeric transcript in a molecular laboratory? -         RT-PCR What is microsatellite instability a result of? -         MSI=expansion/contraction of microsatellite repeats (most in non-coding region) due to mistake in replication (DNA polymerase slippage) AND MMR deficiency (deficiency in mismatch repair proteins) which leads to change in rpt number Mono: AAAAA DInucleotide: CACACACA What is the most common form of genetically determined CRC predisposition and endometrial carcinomas? -         Lynch: germine mutations in MMR gene Explain which gene is likely defective based on the following IHC results: -loss of MLH1 and PMS2 -Loss of MSH6 and MSH2 -Loss of only MSH6 -Loss of only PMS2 -         -loss of MLH1 and PMS2: MLH1 is defective gene -Loss of MSH6 and MSH2: MSH2 is defective gene -Loss of only MSH6: MSH6 is defective -Loss of only PMS2: PMS2 is defective What is the effect of BRAF V600E mutation status on disease recurrence-free probability in PTC? -         Positive V600E--> worse prognosis on all types What is the relationship between therapy and MSI? -         -5_FU may not be effective (and can even be harmful) is MSI=unstable. MSI tumors are more sensitive to irinotecan than stable tumors List the 6 types of hereditary cancers and their associated genes -         1. Breast Cancer BRCA1/2 (also increase risk of pancreatic/prostate cancer) 2. Familial Adenomatus Polyposis (FAP): APC/MYU(MUTYH) genes 3. Cowden Syndrome: PTEN gene 4. Multiple Endocrine Neoplasia (MEN2): RET-proto-oncogene 5. Fanconi Anemia (13 genes) 6. Li-Frauomeni Syndrome: p53 What is MYH-Associated Polyposis (cMAP) -         causes colon cancer and resembles FAP (pheno undistinguishable from FAP other than slightly fewer polyps and later age of onset) -due to mutation in MUTYH/MYH gene (DNA base-excision repair gene). -Autosomal recessive but 100% penetrant What are the characteristics of Lynch (HPNCC)? -