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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. Genes for products that are required at all times.






2. Eukaryotic. mRNA that codes for one protein






3. 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.






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






5. Operons transcribed as single mRNA and mRNA codes for more than one protein.






6. Multiple effects from a single gene






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






8. 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.






9. The process of decreasing the expression of inducible genes






10. 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






11. 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






12. 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.






13. 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






14. 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






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






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






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






18. 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






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






20. 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






21. Select correct ribonucleotides; loss of sigma factor - transcription bubble - no need for primers






22. 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






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






24. 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






25. Gene products decrease in concentration under particular molecular circumstances






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






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






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






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. 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






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






32. 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).






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






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






35. 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






36. 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






37. 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






38. 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






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






40. When arabinose is present - it binds to araC and allosterically induces it to bind to araI instead araO2. If glucose is absent - then the presence of CAP bound to its site between araO1 and araI helps break the DNA loop and helps araC bind to araI






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






42. 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






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






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






45. Gene products increase in concentration under particular molecular circumstances






46. The process of increasing the expression of inducible genes






47. Attenuation






48. 1. mRNA: encodes genetic information 2. tRNA: transfer RNA - involved in protein synthesis (DNA to amino acids) 3. rRNA: ribosome RNA - involved in protein synthesis (polypeptide formation) 4. Ribozymes and RNAi - Can store genetic information and ca






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






50. 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