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Molecular Biotechnology

Subject : engineering
Instructions:
  • Answer 50 questions in 15 minutes.
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  • Match each statement with the correct term.
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This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.
1. Determines amino acid selection. A noncognate amino acid charge incorrectly to the tRNA will be inserted into the protein. Introduce new amino acid by using tRNA for UAG.






2. TrpE through trpA are five enzymes that catalyze the synthesis of the amino acid tryptophan from chorismic acid. If the cell has enough tryptophan - then it doesn't need to waste energy transcribing this mRNA. In the presence of tryptophan - the oper






3. When arabinose is absent - there is no need to express the structural genes. AraC does this by binding simultaneously to araI and araO2 - making a looped DNA. This blocks access to Pbad promoter. AraC is an autoregulator of its own expression and the






4. In the presence of glucose and lactose - bacteria grows first on glucose - then growth levels off - and starts growing on lactose. You have diauxie growth because (1) CAP helps recruit RNAP. in the presence of glucose - CAMP is low so it can't bind t






5. A reading frame without termination codon among 50 or more codons. Usually correspond to genes that encode proteins






6. Chromosome (contains host genetic information) - plasmids (prokaryotes; small - self- replicating DNA; supercoil) - free nucleotides






7. Gene products decrease in concentration under particular molecular circumstances






8. Important to suppress mutations at 3rd position and you don't need to have a lot of stop codons; cells can be more flexible






9. Reverse Transcriptase






10. In E. coli - DNAP III can unwind DNA (helicase) and replicate both strands of DNA. It also has proofreading activity and corrects mistakes 3' to 5' exonuclease






11. 1. Initiation: unwind DNA at the origin of replication (ori) - bidirectional replications; regulated as required for cell division 2. Elongation: requires RNA primer to replicate 3. Termination: signaled by Ter sequence






12. The process in which an exact copy of the double strand DNA is made. It is a templated process and occurs from 5' to 3' end. DNAP - RNA primer; semiconservative (each strand is a template for the replication of the complementary strand)






13. Comprised of >50 proteins associated with rRNA units. Site of protein synthesis and binds mRNA and finds protein synthesis initiation sites. It also binds aa- tRNA and catalyzes peptide bond formation.






14. Search for site to start transcription - unwind DNA; -35 region and pribnow region (-10 region).






15. LacY: Transports lactose into the cell LacZ: B- galactosidase LacA: transacetylase LacI: lacI+ cells fully inducible - lacI- were already induced and not responsive to IPTG X- gal: analog of lactose that turns blue when cleaved by lacZ product and o






16. Nonsense mutation in gene that results in truncated protein can be lethal. Sometimes a second mutation arises that counteracts the effects of the mutation. Amber stop codon (UAG/TAG/etc) and amber suppressor tRNA (CUA/etc) can restore protein size an






17. Attenuation






18. 1. Capping: 5' phosphate capped by 7- methyl guanosine and is a 5'-5' linkage instead of 5'-3' This makes RNA more stable 2. Intron removal 3. Export to cytoplasm 4. Polyadenylated mRNA precursor






19. 1. LacI- makes an internal inducer -- NO. Found that lacI- doesn't dominate over lacI+ and is not always constitutive. 2. LacI- is a repressor protein -- YES. LacI+ dominates over lacI- because when both are together - lac operon is inducible. LacI m






20. The repressor dimer (aporepressor) can't bind to the repressor. Transcription from the promoter is not stopped. When tryptophan is bound to the repressor dimer - the repressor changes configuration so that it can bind to the operator and transcriptio






21. Ribosome doesn't stop at trp codons and stem loop forms between 3 and 4. RNAP stops prematurely (attenuated)






22. 1. Ethidium bromide staining 2. P32 - P33 radioactivity 3. Fluorescence 4. Agarose gel electrophoresis






23. EF-Tu GTP binds with an aminoacyl- tRNA and brings it to the ribosome. Once the correct aminoacyl- tRNA is positioned in the ribosome - GTP is hydrolyzed and EF-Tu* GDP dissociates away from the ribosome






24. Start codon is usually ATG - first amino acid is n - formyl- methionine. It is assisted by initiation factors (IF) and requires ribosomal binding sites (RBS). It is a polycistronic protein translation (operon).






25. Operator site - araC binds to this site and represses its own transcription from the PC promoter. In the presence of arabinose - araC bound at this site helps to activate expression of Pbad promoter






26. Multiple effects from a single gene






27. Need to remove introns before changing into mRNA - then take mRNA out of the nucleus. Has 3 RNAP (RNAP I synthesizes rRNA - II synthesizes mRNA - III synthesizes tRNA and small rRNA). Transcription factors are similar to sigma factors.






28. Gene products increase in concentration under particular molecular circumstances






29. 1. Nucleic acid hybridization: (a) bind single stranded DNA to a membrane support - (b) add single stranded labeled DNA (probe) under appropriate conditions - (c) wash the support to remove excess unbound labeled probe DNA - (d) detect the hybrid seq






30. 1. mRNA - template for protein synthesis 2. tRNA - carrier of amino acid (the adaptor)3. aminoacyl- tRNA synthetase - pairs tRNA with the cognate amino acid - needs ATP 4. ribosome - site of protein synthesis - read in three frames - start codon is A






31. Three sites recruit tRNA and forms peptidyl- tRNA bonds (E - exit; P - peptide; A - acceptor).






32. The ribosome translating the leader peptide arrives at the two tryptophan codons and has to wait for tryptophan. During this time - RNAP continues to transcribe. Stem loop between 2 and 3.






33. Production of commercial products generated by the metabolic actions of microorganisms.






34. Unvarying expression of gene






35. In prokaryotes - related genes often arrayed in tandem. A unit of bacterial gene expression and regulation - recognized by a regulator gene product






36. The first two bases of the codon always form strong Watson -Crick base- pairing. The first base in the anticodon determines the number of codons a tRNA can recognize. The first position in anticodon is often modified to inosine to facilitate wobble b






37. A strand segment complementary to the template with a free 3'OH group






38. Genes for products that are required at all times.






39. A unicellular organism that lacks a nucleus and membrane bound organelles






40. Eukaryotic. mRNA that codes for one protein






41. 1. Synthesis of commercial products by recombinant organisms 2. Biopolymers 3. Bioremediation 4. Biomass utilization






42. Operator site; araC bound at this site can simultaneously bind to the araI site to repress transcription from Pbad promoter






43. When half DNA strand has been denatured. Determined by GC content (triple bond)






44. 4. Cells + organelle 3. Supermolecular complexes 2. Macromolecules 1. Monomeric units






45. Structural and functional units of life. All organisms are made of cells - all cells are derived from preexisting cells - the purpose of a microorganism is to make another microorganisms as quickly as possible; alter metabolism of microorganism to ma






46. The process of increasing the expression of inducible genes






47. A cell that contains a nucleus and membrane bound organelles






48. AARS charges the correct amino acid to tRNA in a two- step reaction.






49. The process of decreasing the expression of inducible genes






50. The small ribosomal subunit binds to 5'-G cap on processed mRNA (no RBS) - uses met instead of fmet for initiation; monocistronic translation