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Unformatted text preview: BICD 100 Genetics Exam 1 January 26, 2009 Prof. Soowal Be sure to put all answers on your scantron. No electronics (calculators, phones, MP3 players, etc.) permitted during exam. BICD 100 Exam 1 2 1. Parts of genes called _________________ are transcribed into RNA but are later removed. a. Exons d. Promoters b. Prions e. None of the above. c. Introns 2. It was discovered that a new species of E. coli is unable to perform post‐
transcriptional modifications. Which process(es) could this particular species be defective in? a. Addition of 5’ poly‐A c. Addition of 3’ cap. tail. d. All of the above. b. Splicing of introns. e. None of the above. 3. A promoter is best described as a(n) a. substance which facilitates RNA transcription. b. sequence of bases at which RNA polymerase begins transcription. c. type of RNA which promotes cell division. d. environmental change which causes transcription to occur. e. None of the above. You are a toxicologist investigating the mechanisms of certain poisons that affect DNA replication. For questions 4 and 5, choose the most likely target of the poison, and the most accurate explanation. 4. A cell that has been treated with substance 190X2 is not able to keep the two parental strands of DNA separated, and so is not able to replicate its chromosomes. a. 190X2 affects single‐stranded binding proteins, which help keep DNA single‐stranded. b. 190X2 affects single‐stranded binding proteins, which help keep DNA nucleotides ligated together. c. 190X2 affects gyrase, which helps keep DNA double‐stranded. d. 190X2 affects gyrase, which helps keep DNA single‐stranded. e. 190X2 affects gyrase, which unwinds DNA. 5. A cell that has been treated with substance 2WX has some ribonucleotides that remain incorporated into the newly‐synthesized daughter strands. a. 2WX affects DNA Polymerase, which elongates the daughter strand. b. 2WX affects DNA Polymerase, which has exonuclease activity that removes RNA primers. c. 2WX affects Primase, which synthesizes RNA primers. d. 2WX affects Primase, which removes RNA primers from the daughter strand. e. 2WX does not affect DNA replication; newly‐synthesized daughter strands usually contain ribonucleotides. BICD 100 Exam 1 3 6. Which of the following is true of DNA replication? a. Bidirectional DNA replication away from an origin of replication is unique to eukaryotes. b. DNA replication requires only deoxyribonucleotides. c. DNA replication occurs in the nucleus. d. DNA replication cannot be bidirectional in organisms whose DNA Polymerases elongate in the 5’ to 3’ direction. e. More than one of the above is true. Match the following terms to the best definition. 7. Giant chromosomes in Drosophila salivary a. Histones glands b. Polytene 8. Beadlike structure consisting of DNA wrapped chromosomes around proteins c. Nucleosomes 9. Repetitive DNA found near the centromeres in d. Satellite DNA higher eukaryotes e. Heterochromatin 10. Small basic proteins that bind to DNA 11. Regions of chromosomes that tend to remain tightly coiled. Before starting work in a new lab, a student received an email asking him to familiarize himself with gnomes in order to prepare for his new project. The industrious student managed to capture a garden gnome, which only come out at midnight when there is a full moon, and draw some blood. Upon analyzing the gnome’s DNA, the student found that the gnome had 4 different bases, but they were different than the A, T, G, and C that most organisms use. He called the 4 bases W, X, Y, and Z. 12. If bases W and X had single rings, while Y and Z had double rings, then what type of bases are Y and Z, and which of the following are possible base pairs? a. Purines; Z‐Y, X‐W b. Purines; Z‐X, Y‐W c. Pyrimidines; Z‐X, Y‐W d. Pyrimidines; Z‐W, X‐Y e. Either C or D. 13. In his analysis of the gnome genome, the student found that the lab had made a mistake – the bases were really A, T, G, and C after all, not W, X, Y, and Z. If the double‐stranded gnome DNA was 16% A, what conclusions can we make about the composition of the other three bases? a. 34% T, 34% G, 16% C b. 32% T, 32% G, 16% C c. 8% T, 16% G, 8% C d. 16% T, 16% G, 16% C e. 16% T, 34% C, 34% C BICD 100 Exam 1 4 14. The genetic code is degenerate because a. mRNA is rapidly degraded. b. the code is not universal among organisms. c. frameshift mutations are tolerated. d. some amino acids have more than one codon. e. stop codons may have corresponding tRNAs. 15. Which of the following is/are characteristics of the genetic code? a. It is a triplet code. b. It is generally nonoverlapping. c. It is almost completely universal. d. (a) and (b) e. All of the above. True/False (A=True; B=False) 16. In eukaryotes, DNA is modified and may undergo splicing to make the mature messenger RNA. 17. The messenger RNA is translated on ribosomes in groups of three nucleotides. 18. Ribosomes are particles consisting of DNA, rRNA, and numerous proteins combined in small and large ribosomal subunits. 19. Nearly all organisms use the standard genetic code with 61 codons for 60 amino acids and 3 stop codons. 20. If a single cell undergoes n mitotic divisions, how many cells will there be once n divisions are complete? a. 1 + 2n b. 2n c. 2n d. 2(n+1) e. 1 + 2n 21. Which of the following statements is/are true about mitosis? I.
Each daughter cell contains approximately one‐half of the parental cell’s cytoplasm. II.
Each daughter cell contains approximately one‐half of the parental cell’s organelles. III.
There is a net increase in the chromosomal number of each cell when compared to the parent cell. a. I only b. II only c. I and II d. II and III e. I, II, and III BICD 100 Exam 1 Questions 22‐24 refer to the following diagram of a diploid cell: 22. How many chromosomes are present? a. 2 b. 4 c. 8 d. 16 e. Cannot determine from the information given. 23. How many chromatids are present? a. 2 b. 4 c. 8 d. 16 e. Cannot determine from the information given. 24. What stage of cell division does the diagram represent? a. Prophase b. Metaphase c. Anaphase d. Telophase e. Cannot determine from the information given. 25. At which phase of the cell cycle are the cells quiescent (inactive)? a. G0 b. G1 c. G2 d. (b) and (c) e. All of the above. 26. What is the major difference between prophase I of meiosis and mitotic prophase? a. Formation of spindle fibers b. Pairing of homologous chromosomes c. Dissolution of nuclear membrane d. Migration of centrioles e. None of the above 5 BICD 100 Exam 1 6 The following table shows the effect of growing mutant strains (I – V)of Neurospora on minimal media supplemented with factors A through F. – represents no growth; + represents growth. Mutant I II III IV V Normal A B C D E F ‐ ‐
‐ ‐ ‐ + ‐ + ‐ ‐ ‐ + ‐ + + + ‐ + ‐ + + ‐ ‐ + + + + + + + ‐ + + + + + 27. What is the most likely order of the biochemical pathway based on the information in the above table? a. A B C D E F b. F E D C B A c. A B D C F E d. B D C F E A e. Cannot determine from the information given. For questions 28‐30, refer to the following diagrams: (a) (b) (c) (d) (e) 28. Which of diagrams shows a phase that is unique to meiosis? 29. Which diagram could be metaphase of mitosis? 30. How many chromosomes are there in diagram (a)? a. 1 b. 2 c. 4 d. 8 e. 12 ...
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