Test 2 Fall 2007

Test 2 Fall 2007 - Bil 255 Test #2 Dr. Glaser Fall 2007...

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Bil 255 Fall 2007 Test #2 – Dr. Glaser FORM 1 Tuesday, Nov 13, 2007 Directions: Choose the BEST answer from among the choices given. 1. Topoisomerases? a. Rewind DNA after the replication fork has passed by b. Open the DNA helix so that replication can start c. Remove the strain on the helix that results from DNA replication 2. When DNA fragments are separated by gel electrophoresis, separation of fragments depends primarily on? a. Size of fragment b. The nucleotide sequence of fragment c. Both a and b apply 3. Ubiquitin is? a. A modified base in RNA b. A protease c. A small protein which when linked to other proteins targets them for degradation in lysosomes d. A small protein that stabilizes other proteins e. A small protein that when linked to cellular proteins target them for degradation in proteosomes 4. When you compare the exon sequences present in an initial gene transcript with the sequences in the mature message? a. All the exon sequences are present in the mature message b. The mature message may only contain some of the exon sequences 5. In order for mRNA to exit from the nucleus it most have? a. A methyl G at the 3’ end b. A methyl G at the 5’ end c. A poly A tail d. a and c apply e. b and c apply 6. Aminoacyl tRNA synthetase? (think carefully) a. Recognizes the anticodon of the tRNA and this is sufficient for the reaction to proceed (i.e. link an amino acid to the tRNA. b. The enzymes also recognize other sequences in the tRNA 7. Amino acids are linked to tRNA at? a. At its 5’ end b. At its 3’ end c. The terminal nucleotide which is Adenine d. a and c apply e. b and c apply 8. After completing protein synthesis the ribosomal subunits? a. Remain bound to each other b. Are separated 9. In eukaryotes the ribosome identifies a mRNA by the presence of a methyl G cap. In prokaryotes? a. The same applies b. Each coding sequence is preceded by a unique sequence in a polycistronic message The next two questions are related 10. All proteins in a given cell type are degraded? a. Randomly b. Different protein are degraded at different rates 11. Proteins are normally degraded in a pathway that requires: a. The nucleus b. In proteosomes c. Marked by ubiquitin d. ATP e. only b, c, and d apply
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Bil 255 fall 2007 – test #2 = FORM 1 – page 2 The next two questions are related 12. Ultraviolet light results in the formation of? a. A cross linked A-A base pair b. A cross linked T-T base pair 13. For the answer to question above, the cross linked bases are? a. On opposite strands b. On the same strand c. Both can occur 14. Human females have two X chromosomes while males have one, therefore they: (think carefully) a. Synthesize twice as many gene products coded by the X chromosome b. They randomly inactivate half the genes on each X chromosome c. They inactivate a specific set of genes in each X chromosome, so that each chromosome only expresses a different half of the X chromosome genes d. None of the above is correct 15. When DNA is chemically damaged, DNA repair requires?
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Test 2 Fall 2007 - Bil 255 Test #2 Dr. Glaser Fall 2007...

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