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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. 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).






2. 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






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






4. 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






5. Multiple effects from a single gene






6. A small catabolite molecule. Its level is determined by the level of glucose in the cell where glucose controls the rate of cAMP formation with ATP. When there is high glucose - there is low levels of cAMP. cAMP activator protein (CAP) has to bind cA






7. 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






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






9. Eukaryotic. mRNA that codes for one protein






10. A templated process just like in DNA replication and there is no processing steps.






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






12. 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






13. A haploid organism that is diploid for a small region of the chromosome (partial diploid)






14. 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.






15. Gene products decrease in concentration under particular molecular circumstances






16. Reverse Transcriptase






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






18. 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






19. Unvarying expression of gene






20. Replication > DNA > Transcription > RNA > Translation > Protein






21. 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






22. 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






23. Release DNA - rewind DNA - release RNA; stop signals or rho mediated termination (hairpin is a palindromic GC- rich region followed by an AT- rich region; Rho is a termination factor that binds to nascent RNA) RNAP has sigma factor that recognizes pr






24. 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






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






26. Codes for three enzymes needed to catalyze the metabolism of arabinose. The operon is regulated by araC gene product.






27. Attenuation






28. 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






29. Functions: enzymes - regulation - structural - cellular functions Polymers of amino acids and connected by peptide bonds. Can fold into complex structures.






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






31. 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






32. Expression levels rise and fall in response to molecular signals






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






34. 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






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






36. 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






37. 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






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






39. 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






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






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






42. Polymerase binds to lac promoter weakly by itself and results in low levels of transcription even in the absence of lacI. The activator recruits the polymerase to the promoter region and increases its affinity for the promoter






43. 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.






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






45. Inducer site; araC bound at this site can simultaneously bind to the araO2 site to repress transcription from the Pbad promoter. In the presence of arabinose - araC bound at this site helps to activate expression of Pbad promoter.






46. The process of decreasing the expression of inducible genes






47. Binds to CAP binding site. In conjunction with araC bound with arabinose - it assists RNAP in binding to the Pbad promoter






48. A segment of DNA molecule contains the information required for synthesis of a functional biological product






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






50. The process of increasing the expression of inducible genes