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AGR 3303 (3 credits) University of Florida - Fort Lauderdale  |
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| Below is exam #2 for 1994, Molecular genetics |
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AGR 3303 - Genetics 14 Nov 1994 University of Florida - Fort Lauderdale Exam #1: MOLECULAR GENETICS
Multiple choice. (69 pts.) Please read these carefully. Only one response correctly answers the question, or completes the statement. Circle the corresponding letter (a, b, c, d, or e). 1. Based on the idea of bacterial transformation, what might happen if you mixed avirulent bacteria with heat-killed virulent bacteria and injected this mixture into a mouse? a. the same as injecting just heat-killed virulent bacteria b. the same as injecting just virulent bacteria c. the same as injecting just heat-killed avirulent bacteria d. the same as injecting just avirulent bacteria e. none of the above 2. A gene can be defined as: a a chemical factor of inheritance b a polypeptide c the product of transcription d the product of translation e all of the above 3. A single piece of single-stranded DNA reads 5' CGGCATTAC 3'. Which of the following pieces of single-stranded DNA could form a normal, complimentary double helix with the original piece? a. 5' GTAATCGGC 3' b. 5' GTAATGCCG 3' c. 5' CGGCTAATG 3' d. 5' GCCGTAATG 3' e. 5' GTATACGGC 3' 4. A large molecule made up of amino acids is: a. DNA b. tRNA c. starch d. polypeptide e. all of the above 5. A class of molecules that recognizes codons: a. ribosome b. mRNA c. restriction endonuclease d. tRNA e. amino acid 6. DNA forensics does not use: a. restriction fragment length polymorphisms b. repetitive DNA c. probability d. hemoglobin e. semen 7. Which is always true? a. polypeptides are enzymes b. proteins are polypeptides c. proteins are enzymes d. proteins are histones e. histones are enzymes 8. A cell-free synthesizing system was used to translate the genetic code, using artificial RNA templates. RNA sequences in these templates were matched to amino acid(s), based on the retention of radioactively labelled amino acid. Which concept(s) would be reasonably help the deciphering effort. a. RNA homopolymers should code for only one amino acid b. RNA heteropolymers could code for more than one amino acid c. the ratio of nucleotides predicts the ratio of amino acids d. all of the above e. none of the above 9. The Central Dogma examines which characteristic of the genetic material? a. mutation b. expression c. replication d. all of the above e. none of the above 10. The actual method of DNA synthesis leads to Okazaki fragments because: a. new DNA synthesis occurs in the 5'-3' direction on one strand, and 3'-5' on the other strand b. DNA synthesis is continuous on both strands c. new DNA synthesis occurs in the 5'-3' direction on both strands d. DNA synthesis takes place in the nucleus, while protein synthesis occurs in the cytoplasm e. DNA synthesis is conservative 11. DNA polymerase is active in: a. replication b. transcription c. translation d. all of the above e. none of the above 12. In replication, each double-stranded daughter DNA is composed of one strand which is old and one which is newly synthesized, thus replication: a. has fidelity b. is collinear c. is semiconservative d. is bidirectional e. involves complementarity 13. Translation normally requires: a. ribosomes b. ribosomes and tRNA c. ribosomes, tRNA, and mRNA d. ribosomes, tRNA, mRNA, and amino acids e. ribosomes, tRNA, mRNA, amino acids, and polymerase 14. A mutant allele can be recessive because: a. oligomeric proteins can be inactivated by only one of their components b. the mutation is masked by another gene c. it produces a defective enzyme, while the normal allele on the homologous chromosome produces functional enzyme d. all of the above e. none of the above 15. The basic unit of double-stranded DNA is a(n): a. amino acid b. nitrogenous base c. nucleotide d. ribosome e. nucleosome 16. Complementarity is important in: a. replication b. transcription c. translation d. all of the above e. none of the above 17. Watson and Crick (1953) discovered: a. the genetic code b. that DNA is the hereditary molecule c. the Central Dogma d. the structure of DNA e. genetic engineering 18. Heterochromatin: a. constitutes genetically inactivated chromosome regions b. contains mostly single copy DNA c. stains darkly during interphase d. all of the above e. none of the above 19. DNA is recovered from alien passengers on a UFO. The DNA contains the following composition of bases: adenine 22%, guanine 16%, thymine 10%, cytosine 52%. The aliens most likely have: a. single-stranded DNA b. single-stranded RNA c. double-stranded DNA d. double-stranded DNA e. jet lag 20. In the lac operon, a. lactose binds with the DNA, preventing transcription b. lactose binds with a protein, preventing translation c. a protein binds with the DNA, preventing transcription d. there are three regulatory genes and one structural gene e. translation results in lactose 21. Human insulin can be produced by bacteria, using human DNA. This proves that: a bacteria and humans have repetitive DNA b the genetic material is DNA c bacteria have the same genes as humans d bacteria are endosymbionts e genetic engineering is free of risks 22. The bacteria of Avery et al. (1944) were transformed by a substance which remained active: a after spontaneous creation b when radioactive 32P was detected c after treatment by RNase d after treatment by DNase e all of the above 23. Enzymes: a. raise the activation energy b. assist in chemical reactions c. occur in the cytoplasm, not the nucleus d. occur in the nucleus, not the cytoplasm e. were first invented by soap manufacturers to boost the ratings of daytime television
Matching (20 pts.) In each of the following twenty-one blank spaces, insert the correct word or phrase from the list at the bottom of the page. 24. The form of the DNA molecule, as proposed by Watson and Crick
__________________________________. 25. The three-nucleotide "word" in mRNA, which specifies a single amino acid
__________________________________. 26. An oligomeric protein which is important in connective tissue
__________________________________. 27. A method for amplifying DNA segments to large number of copies
__________________________________. 28. A type of mutation involving a deletion or an insertion of one or more nucleotides, resulting in a garbled message
__________________________________.
29. A type of organism which has considerable noncoding, repetitive DNA
__________________________________. 30. A cutter enzyme used in genetic engineering
__________________________________. 31. An organelle which is believed to have been an ancient cellular invader; a possible endosymbiont
__________________________________. 32. The regulatory gene which binds with a repressor protein, preventing RNA polymerase from binding with the promoter, thus preventing transcription
__________________________________. 33. "Wobble" in the third nucleotide of tRNA's anticodon is believed to result in inexact complementarity. This permits what key characteristic of the genetic code?
__________________________________. 34. The correspondence between the sequence of nucleotides and the sequence of amino acids resulting from translation
__________________________________. 35. A nitrogenous base present in RNA, but not in DNA
__________________________________. 36. A labelled macromolecule, such as DNA, which is used to detect target molecules, such as genetic sequences; can be used for early disease diagnosis
__________________________________. 37. A type of protein made of two or more polypeptides
__________________________________. 38. A short-lived molecule produced in the nucleus which moves to the ribosomes
__________________________________. 39. A discredited model for the structure of DNA, based on erroneous data suggesting equal composition of bases A, T, G, and C
__________________________________. 40. Virus which attacks bacteria; often used in genetic studies
__________________________________.
41. An organism lacking a nucleus
__________________________________. 42. A process of sudden genetic change, the source of most alleles
__________________________________. 43. The place in a protein where structural integrity is required for function; mutations which disrupt the protein here usually result in defective protein
__________________________________.
Short answer 44. What is the advantage to an organism in having regulatory genes (25 words or less)? (3 pts.)
45. Mutations occur with varying effects on the organism; here are some examples. Imagine that point mutations (nucleotide changes) occur in a structural gene (one which contains the message for a protein). Please explain how the different effects might arise. (Hint, the mechanisms are: Is the mutation a frameshift? Is the protein oligomeric or monomeric (in a diploid with two homologous chromosomes)? Is the protein active site affected? Does the nucleotide substitution result in a redundant codon? You can explain the effect by stating the corresponding mechanism and describing why the effect would occur. ) (8 pts.)
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