Infinity Academy Nucleic Acid Structure Questions PDF

Infinity Academy ‫البوابة الشمالية لجامعة اليرموك‬-‫ اربد‬/‫ضاجية الرشيد‬-‫عمان‬ 0795350650 ‫للتسجيل واالستفسار مدير االكاديمية المهندس محمد الحجي‬ Nucleic acid structure Questions 1. Which of the following oligonucleotides forms the most stable...

Infinity Academy ‫البوابة الشمالية لجامعة اليرموك‬-‫ اربد‬/‫ضاجية الرشيد‬-‫عمان‬ 0795350650 ‫للتسجيل واالستفسار مدير االكاديمية المهندس محمد الحجي‬ Nucleic acid structure Questions 1. Which of the following oligonucleotides forms the most stable duplex with the DNA fragment 5’GTTGACTGCA3’ A. 5’CAACTGACGT 3 B. 5’TGCAGTCAAC 3’ C. 5’CAACGGGCGT 3’ D. 5’TGCGGGCAAC 3’ E. 5’ACGTCAGTTG 3’ 2. Most of the DNA in the eukaryotic nucleus is packaged in nucleosomes with A. histones B. ribonuclear proteins C. ribosomal proteins D. topoisomerases E. DNA a,b proteins 3. A double-stranded DNA fragment contains 0.2 mole-fraction of A (adenine). The mole-fractions of other bases are: A. T=0.2, G=0.3, and C=0.3 B. T=0.3, G=0.2, and C=0.3 C. T=0.3, G=0.3, and C=0.2 D. T=0.2, G=0.4, and C=0.2 E. not possible to calculate with the information given. 4. Place the following components of the chromosome in hierarchal order starting with the smallest component and ending with the largest. 1) nucleofilament 2) base pair 3) nucleosome. 4) nucleotide 5) metaphase chromosome. 6) Condensed scaffold form. A. 2 < 4 < 3 < 1 < 6 < 5. B. 4 < 2 < 3 < 1 < 6 < 5. C. 2 < 4 < 3 < 6 < 1 < 5. D. 4 < 2 < 3 < 1 < 5 < 6. E. 4 < 2 < 3 < 6 < 1 < 5. 5. Adjacent nucleotides are joint by a : A. 5’-3’ phosphodiester bond B. 3’-5’ phosphodiester bond C. glycosidic bond D. deoxyribose E. hydrogen bonds 1|P a g e Dr.Tareq Jibril ……0790979188  Infinity Academy ‫البوابة الشمالية لجامعة اليرموك‬-‫ اربد‬/‫ضاجية الرشيد‬-‫عمان‬ 0795350650 ‫للتسجيل واالستفسار مدير االكاديمية المهندس محمد الحجي‬ 6. Which one of the following double-slandered DNA molecules has the lowest melting** temperature (Tm)? A. GCGCGCGC CGCGCGCG B. GCCATGGC CGGTACCG C. GGAATTCC CCTTAAGG D. GAAATTTC CTTTAAAG E. ATATATAT TATATATA 7. Flow of genetic information from DNA to DNA in the central dogma of molecular genetics: A. Replication B. Translation C. Transcription D. Reverse transcription E. Recombination 8. Increase absorption at 260 nm which occurs when DNA is denaturated is referred to: A. DNA Breathing B. DNS Melting C. Hypochromacity D. Hyperchromicity E. Ionization 9. Which form of DNA was discovered by Rosalind Franklin: A. Z B. C C. A D. B E. D 10. Nucleosomes Core includes all of the following Except: A. H1 B. H2A C. H2B D. H3 E. H4 2|P a g e Dr.Tareq Jibril ……0790979188  Infinity Academy ‫البوابة الشمالية لجامعة اليرموك‬-‫ اربد‬/‫ضاجية الرشيد‬-‫عمان‬ 0795350650 ‫للتسجيل واالستفسار مدير االكاديمية المهندس محمد الحجي‬ 11. In a double stranded DNA molecule one strand is analyzed and found to contain 20A, 25G, 30C, 22T. The overall composition of the double strand is? A. T:44, G:50, C:60, A:40 B. T:42, G:55, C:55, A:42 C. T:60, G: 26, C:34, A:30 D. T: 22, G:25, C:30, A:20 12. The backbone of a DNA molecule is composed of which of the following? A. Alternating sugars and nitrogenous bases. B. Nitrogenous bases alone. C. Phosphate groups alone. D. Alternating phosphate and sugar group. E. Five carbon sugars alone. 13. The Order of bases from left to right: A. U A G C T B. T G A C U C. A T C G U D. T A G U C E. T A G C U 14. A segment of DNA has the following sequence pTpApCpGpTpGpC. Which of the sequences below would represent the complement of this DNA strand? A. pApTpGpCpApCpG B. pGpCpTpGpCpApT C. pGpCpApCpGpTpA D. pTpApCpGpTpGpC E. none of the above 15. If in one strand of DNA, reading in the 5' to 3’ direction, the nucleotide sequence is GCC, the nucleotide sequence in the complementary strand, again in the 5' to 3’ direction, is A. GCC. B. GGC. C. CGG. D. ATT. 16. Which molecular feature listed causes duplex DNA to exhibit a near constant width along its long axis? A. A purine nitrogenous base always pairs with another purine nitrogenous base. B. A pyrimidine nitrogenous base always pairs with another pyrimidine nitrogenous base. C. A pyrimidine nitrogenous base always pairs with a purine nitrogenous base. D. Repulsion between phosphate groups keeps the strands a uniform distance apart. E. Attraction between phosphate groups keeps the strands a uniform distance apart 3|P a g e Dr.Tareq Jibril ……0790979188  Infinity Academy ‫البوابة الشمالية لجامعة اليرموك‬-‫ اربد‬/‫ضاجية الرشيد‬-‫عمان‬ 0795350650 ‫للتسجيل واالستفسار مدير االكاديمية المهندس محمد الحجي‬ 17. The nucleotide sequence 5'-ATTGCAG-3' should base pair with A. 5'-TAACGTC-3'. B. 5'-CTGCAAT-3'. C. 3'-ATTGCAG-5'. D. 3'-CTGCAAT-5'. 18. Spontaneous conversion of adenine and cytosine from the amino to the imino forms of these bases within DNA results in: A. cleavage of the glycosidic bond and loss of the base. B. cleavage of the 3', 5' phosphodiester DNA backbone. C. alteration of the hydrogen bonding of the bases. ‫غير مطلوب‬ D. formation of guanine and thymine respectively. 19. Because of the phosphate groups, DNA is A. basic. B. acidic. C. neutral. D. tightly bonded. E. none of the above. 20. The term denaturation, when used in connection with nucleic acids or proteins refers to a change in structural characteristics due to A. the disruption of covalent bonds. B. the disruption of non-covalent bonds. C. the binding of toxic compounds. D. changes in primary structure. E. changes in the state of aggregation. 21. In the Watson-Crick structure for DNA A. the DNA strands run parallel. B. the ratio of G to A equals 1. C. the ratio of A to U equals 1. D. the number of purines equals the number of pyrimidines. E. two of the above are correct 22. The Tm (melting temperature) of DNA A. is unrelated to the base composition. B. is a constant for all DNA samples. C. is linearly related to the guanine + cytosine content. D. is proportional to the uridine content. E. None of the other answers is correct. 23. The major structural protein component(s) of chromatin are A. tubulin. B. actin. C. histones. D. acidic chromosomal proteins. E. myosin. 4|P a g e Dr.Tareq Jibril ……0790979188  Infinity Academy ‫البوابة الشمالية لجامعة اليرموك‬-‫ اربد‬/‫ضاجية الرشيد‬-‫عمان‬ 0795350650 ‫للتسجيل واالستفسار مدير االكاديمية المهندس محمد الحجي‬ 24. Denaturation of double stranded DNA with heat or alkali results in all of the following EXCEPT A. decreased absorbance of the DNA at 260 nm. B. loss of base stacking. C. formation of single stranded DNA. D. disruption of hydrogen bonding. E. a helix to coil transition. 25. Which of the following statements is correct concerning native DNA? A. The two strands are the same in base sequence. B. The sugar-phosphate backbones contain the five-carbon sugar ribulose. C. The analysis A = G and C = T is expected. D. Both strands run in the same direction. E. None of the above. 26. Hyperchromic shift is caused by A. high GC content. B. high AT content. C. melting of double stranded DNA. D. cooling of double stranded DNA. E. none of the above 27. All of the following statements concerning the Watson-Crick Model of DNA structure are true EXCEPT A. the two strands of DNA are complementary. B. the hydrogen bonding between guanine and cytosine is stronger than between adenine and thymine. C. the two DNA strands are anti-parallel. D. The helical structure of the DNA is right handed E. the stacked nitrogenous bases form the backbone of each DNA strand 28. The H1 histone A. is one of the four histones in the nucleosome core. B. helps form the octamer nucleosome complex. C. contain high content of acidic amino acids D. is present at 1:1 weight ratio with DNA. E. helps fold the bead-on-a-string structure into higher order structures. 29. Which of the following forms structural histones octamer? A. H1 B. H2A and H2B C. H3 and H4 D. All histones E. All histones except H1 5|P a g e Dr.Tareq Jibril ……0790979188  Infinity Academy ‫البوابة الشمالية لجامعة اليرموك‬-‫ اربد‬/‫ضاجية الرشيد‬-‫عمان‬ 0795350650 ‫للتسجيل واالستفسار مدير االكاديمية المهندس محمد الحجي‬ 30. Which of the following statements describing DNA structure is False? A. The double helical structure has two grooves running regularly along its length one is larger than the other B. The two chains in the double helix have antiparallel direction C. The classical hydrogen bonding between A/T and G/C is found in the Z-form of DNA D. Helical structure is stabilized only by hydrogen bonds 31. Forces normally contributing to the stability of the double helix in native DNA include all of the following EXCEPT: A. Hydrogen bonding B. Hydrophobic interaction C. Interstrand cross-links D. Stacking forces E. None of the choices 32. Which of the following forms of eukaryotic DNA structure is the most common? A. A-DNA B. B-DNA C. Z-DNA D. Bent DNA E. Rosalind franklin DNA 33. Which of the following about structural forms of DNA is False? A. B-DNA is the predominant form of DNA in living systems B. Z-DNA has higher number of bases pairs per turn than A-DNA C. A-DNA is obtained by moderately dehydrating B-DNA D. Z-DNA is commonly encountered in areas of alternating poly dG-dC E. Structural forms can never change from one another 34. Which of the following components are found in DNA? Choose the most complete answer. A. A phosphate group, adenine, and ribose B. A phosphate group, guanine, and deoxyribose C. Cytosine and ribose D. Thymine and deoxyribose E. A phosphate group and adenine 35. Which of the following is the interconnecting bond that connects the nucleotides of RNA and DNA? A. N-glycosidic bonds B. 3’-5’ phosphodiester linkages C. Phosphomonoesters D. 2’-3’phosphodiester linkages E. Peptide nucleic acid bonds 6|P a g e Dr.Tareq Jibril ……0790979188  Infinity Academy ‫البوابة الشمالية لجامعة اليرموك‬-‫ اربد‬/‫ضاجية الرشيد‬-‫عمان‬ 0795350650 ‫للتسجيل واالستفسار مدير االكاديمية المهندس محمد الحجي‬ 36. Which component of the DNA duplex causes the molecule to have a net negative charge at physiologic pH? A. Deoxyribose B. Ribose C. Phosphate groups D. Chlorine ion E. Adenine 37. In DNA double helix: A. The individual strand is not helical B. Hydrogen bonds form between a purine and pyrimidine base on the same strand C. Adenine on one strand is hydrogen bonded to thymine on the opposite strand D. Phosphodiester bonds are oriented toward the interior of the helix E. The outside of the helix is neutral 38. The A-helix of DNA differs from the B-helix in all of the following EXCEPT: A. Number of base pairs per turn B. Helix rise of the base pairs relative to helix axis C. Thickness of the helix D. Tilt of the base E. Polarity of the strands 39. A nucleic acid was analyzed and found to contain 37% A, 16% G, 22% C, and 25% T. the nucleic acid must be: A. Single stranded RNA B. Single stranded DNA C. Double stranded RNA D. Double stranded DNA E. RNA-DNA hybrid 40. Which of the following is not a feature of B-DNA? A. The strands of DNA run in an antiparallel fashion B. B-DNA has a major and minor groove extending along the entire helix C. There are approximately 13 base pairs per turn D. The helix rise of each base pair is 0.34 nm E. The diameter is approximately 2 nm 41. Which of the following amino acids are essential for histone binding to DNA? A. Lysine and Arginine B. Glutamate and Asparate C. Glutamin and Asparagine D. Glycine and Valine E. Serine and Threonine 7|P a g e Dr.Tareq Jibril ……0790979188  Infinity Academy ‫البوابة الشمالية لجامعة اليرموك‬-‫ اربد‬/‫ضاجية الرشيد‬-‫عمان‬ 0795350650 ‫للتسجيل واالستفسار مدير االكاديمية المهندس محمد الحجي‬ 42. Which of the following DNA molecules with the melting points as given, has the highest AT content? A. 35C° B. 52C° C. 77C° D. 63C° E. Melting point has nothing to do with AT content 43. Suppose that RNA is the genetic material which of the following would be unable to transform R- strain to S-strain streptococcus pneumonia when added to living R-cells? A. Heat-killed S-cells extracts B. Heat-killed S-cells extract treated with deoxyribonuclease (DNAases) C. Heat-killed S-cells extract treated with ribonuclease (RNAases) D. Heat-killed S-cells extract treated with proteases ‫غير مطلوب‬ E. Heat-killed S-cells extract treated with phospholipases 44. Name the mechanism through which RNAs are synthesized from DNA? A. RNA replication B. Translation C. Reverse transcription D. Reverse translation E. Transcription 45. which of the following would inactivate the transformation of R streptococcus pneumonia to S-cells when added to S-cells extract? A. DNase ‫غير مطلوب‬ B. RNase C. proteolytic enzymes D. polysaccharide E. Topoisomerase 46. What structure is this?? A. Purine nucleotide B. Purine C. Purine nucleoside D. Pyrimidine nucleoside E. Deoxyadenosine 47. In DNA, the bond between the deoxyribose sugar and the phosphate is which of the following? A. A glycosidic bond B. A hydrogen bond C. A covalent bond D. An ionic bond E. A van der Waals bond 8|P a g e Dr.Tareq Jibril ……0790979188  Infinity Academy ‫البوابة الشمالية لجامعة اليرموك‬-‫ اربد‬/‫ضاجية الرشيد‬-‫عمان‬ 0795350650 ‫للتسجيل واالستفسار مدير االكاديمية المهندس محمد الحجي‬ The following structure is the primary structure of DNA, based on this structure please answer the following 6 question 48. The end of DNA labelled A is: A. N-terminus. B. C-terminus. C. 5’-end. D. 3’-end E. Cannot be determined. 49. The bond labelled C is: A. N1-C5’ N-β-glycosidic bond. B. N1-C9’ N-β-glycosidic bond. C. N9-C1’ N-β-glycosidic bond. D. 3’-5’ phosphodiester bond. E. Hydrogen bond. 50. The number of the atom labelled D is: A. 1' B. 3 C. 3' D. 5 E. 5' 51. The base labelled B is: A. Adenine. B. Thymidine. C. Guanine D. Thymine E. Thiamine 52. In Z-form of DNA the bond labeled C would have? A. Anti configuration B. Syn configuration ‫غير مطلوب‬ C. C2’ endo D. C3’ endo E. C8 hydrogen atom above the pentose sugar Oxygen 53. In B-form of DNA the deoxyribose involved in the bond C would have? A. Anti configuration B. Syn configuration ‫غير مطلوب‬ C. C2’ endo D. C3’ endo E. C3’ oriented to the same side of the nitrogenous base 9|P a g e Dr.Tareq Jibril ……0790979188  Infinity Academy ‫البوابة الشمالية لجامعة اليرموك‬-‫ اربد‬/‫ضاجية الرشيد‬-‫عمان‬ 0795350650 ‫للتسجيل واالستفسار مدير االكاديمية المهندس محمد الحجي‬ 54. Which of the DNA's, with the melting points as given, has the highest percent of G-C pairs? A. 84 C° B. 73 C° C. 69 C° D. 78 C° E. 92 C° 55. the approximate number of helical turns in a 1K bp B-DNA molecule is A. 100 B. 1000 C. 1 D. 10 E. 340 56. the figure below shows melting curve of the same DNA sample in aqueous solution at different ionic strength, what is the Tm for the DNA sample in a solution that has the highest ionic strength? A. 50 °C B. 68 °C C. 88 °C D. 110 °C E. 120 °C 57. which of the following statement about the melting curve shown in the figure is incorrect? A. the DNA at point A is double stranded helical molecule B. CG rich regions start to melt at point B C. more than 50% of the DNA sample is denaturated at point D D. the double stranded DNA molecule is fully denaturated into randomly coiled single stranded DNA at point E E. point C represent the Tm for the DNA sample 58. which point on the graph represent the temperature at which half of the maximal absorbance increase is attained? A. A B. B C. C D. D E. E 59. which of the following DNA structures has the largest number of base pairs per turn A. A-DNA B. B-DNA C. Z-DNA D. both A-DNA and B-DNA E. all types of DNA have the same numbers of base pairs per turn 10 | P a g e Dr.Tareq Jibril ……0790979188  Infinity Academy ‫البوابة الشمالية لجامعة اليرموك‬-‫ اربد‬/‫ضاجية الرشيد‬-‫عمان‬ 0795350650 ‫للتسجيل واالستفسار مدير االكاديمية المهندس محمد الحجي‬ 60. Hypochromic shift is caused by A. high GC content. B. high AT content. C. melting of double stranded DNA. D. reannealing of the ssDNA molecules to form dsDNA E. none of the above 61. a double stranded DNA molecule composed of 200 nucleotides is analyzed and found to have 25A, the complete composition of this DNA molecule is: A. 25A, 25T, 25G, 25C B. 50A, 50T, 50G, 50C C. 25A, 25T, 50G, 50C D. 25A, 25T, 75G, 75C E. 50A, 50T, 25G, 25C 62. The most abundant type of RNA in living cells is? A. tRNA B. rRNA C. mRNA D. snRNA E. siRNA 63. the amino acid attachment site of tRNA is? A. 5’ACC3’ B. 5’CCA3’ C. 5’UCC3’ D. 5’CCU3’ E. Differ from one tRNA to another 64. Which of the following contain methy-guanosine Cap at the 5’end? A. tRNA B. polycistronic mRNA C. eukaryotic mature mRNA D. rRNA E. all eukaryotic RNA molecules 65. which of the following RNA molecules act as an adaptor during the synthesis of polypeptides? A. rRNA B. tRNA ‫غير مطلوب‬ C. mRNA D. snRNA E. rRNA, tRNA, and mRNA 11 | P a g e Dr.Tareq Jibril ……0790979188  Infinity Academy ‫البوابة الشمالية لجامعة اليرموك‬-‫ اربد‬/‫ضاجية الرشيد‬-‫عمان‬ 0795350650 ‫للتسجيل واالستفسار مدير االكاديمية المهندس محمد الحجي‬ Question Answer Question Answer Question Answer 1 B 23 C 45 A 2 A 24 A 46 C 3 A 25 E 47 C 4 B 26 C 48 C 5 B 27 E 49 C 6 E 28 E 50 C 7 A 29 E 51 D 8 D 30 D 52 B 9 C 31 C 53 C 10 A 32 B 54 E 11 B 33 E 55 A 12 D 34 B 56 D 13 D 35 B 57 B 14 C 36 C 58 C 15 B 37 C 59 C 16 C 38 E 60 D 17 B 39 B 61 D 18 C 40 C 62 B 19 B 41 A 63 B 20 B 42 A 64 C 21 D 43 C 65 B 22 C 44 E 12 | P a g e Dr.Tareq Jibril ……0790979188