a. transcription b. duplication c. transformation d. replication a. viruses b. enzymes c. coils of DNA d. form of bacteria

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1 PRTIE TEST HPTER 12 KEY Name Period ate Seat 1. The process by which one strain of bacterium is apparently changed into another strain is called a. transcription b. duplication c. transformation d. replication 2. Bacteriophages are B a. viruses b. enzymes c. coils of N d. form of bacteria 3. Before N could be shown to be the genetic material in cells, scientists had to show that it could a. tolerate high temperatures b. carry and make copies of information c. be modified in response to environmental conditions d. be broken down into small subunits 4. nucleotide does NOT contain a a. 5-carbon sugar c. phosphate group b. nitrogenous base d. protein 5. ccording to hargaff s rule of base pairing, which of the following is true about N? a. = T, and = G c. = G, and T = b. =, and T = G d. = T = = G 6. The bonds that hold the two strands of N together come from a. the attraction of phosphate groups for each other. b. strong bonds between nitrogenous bases and the sugar-phosphate backbone. c. hydrogen bonds between nitrogenous bases. d. carbon-to-carbon bonds in the sugar portion of the nucleotides. 7. In prokaryotes, N molecules are located in the a. nucleus b. ribosomes c. cytoplasm d. histones 8. In eukaryotes, nearly all the N is found in the a. nucleus b. ribosomes c. cytoplasm d. histones 9. The main enzyme involved in linking individual nucleotides into N molecules is a. N protease c. carbohydrase b. Ribose d. N polymerase 1

2 PRTIE TEST HPTER 12 Use figure 12.1 to answer questions The diagram below shows the process of N a. replication. b. digestion. c. transformation. d. transpiration. 11. The molecule labeled X is a a. histone. c. N polymerase b. ribosome d. nucleotide 12. The molecule labeled Y is a a. histone c. N polymerase b. ribosome d. nucleotide Figure 12.1 scientist studied the effect of exposing N to various wavelengths of ultraviolet light. The scientist determined the number of copying errors made after exposure to ultraviolet rays. The graph shows the results. Use the graph to answer questions 13and 14. 2

3 PRTIE TEST HPTER 12 B 13. The most damaging effects of ultraviolet light on N replication occur closest to what wavelength? a. 200 b. 250 c. 300 d What conclusion would you draw from the graph about the effect of ultraviolet light on living organisms? Ultraviolet light, particularly between 250 and 270 nm wavelengths, is harmful to living organisms. The following table shows the results of measuring the percentages of the four bases in the N of several different organisms. Some of the values are missing from the table. 15. omplete the table by calculating the missing values. Nitrogenous Bases (%) Organism G T Human hicken Bacterium (S. Lutea) uring replication, which sequence of nucleotides would bond with the N sequence TTG? The sequence would be TT 17. The scientist(s) responsible for the discovery of bacterial transformation is (are) a. Watson and rick c. Griffith b. very d. Franklin 18. Which of the following does NOT describe the structure of N? a. double helix b. nucleotide polymer c. contains adenine-guanine pairs d. sugar-phosphate backbone 3

4 PRTIE TEST HPTER What did Hershey and hase s work show? B a. Genes are probably made of protein. b. Viruses contain N but not protein. c. Bacteria contain N but not protein. d. Genes are probably made of N. 20. The two backbones of the N molecule consist of a. adenines and sugars. c. adenines and thymines. b. phosphates and sugars d. thymines and sugars. 21. In eukaryotic chromosomes, N is tightly coiled around proteins called a. N polymerase. c. histones. b. nucleotides.. chromatin. 22. When prokaryotic cells copy their N, replication begins at a. one point on the N molecule. b. two points on opposite ends of the N molecule. c. dozens to hundreds of points along the molecule. d. opposite ends of the molecule. 23. ompared to eukaryotic cells, prokaryotic cells contain Questions a. about 1000 times more N b. twice as much N c. the same amount of N d. about one thousandth as much N Under ideal conditions, a single bacterial cell can reproduce every 20 minutes. The graph shows how the total number of cells under ideal conditions can change over time. 4

PRTIE TEST HPTER 12 24. How many cells are present after 80 minutes? a. 1 b. 2 c. 16. d. 32 25.

5 PRTIE TEST HPTER How many cells are present after 80 minutes? a. 1 b. 2 c. 16. d If the N of this bacterium is 4 million base pairs in length, how many total molecules of, T,, and G are required for replication to be successful? a. 2 million b. 4 million c. 8 million d. 32 million 26. escribe how eukaryotic cells are able to keep such large amounts of N in the small volume of the cell nucleus. In eukaryotic cells, N is tightly wound and coiled around proteins and coiled again and again to form chromosomes. This means that a very large amount of N can be stored in a small space. 27. very and his team identified N as the molecule responsible for the transformation seen in Griffith s experiment. How did they control variables in their experiment to make sure that only N caused the effect? In eukaryotic cells, N is tightly wound and coiled around proteins and coiled again and again to form chromosomes. This means that a very large amount of N can be stored in a small space. 28. escribe the components and structure of a N nucleotide. nucleotide has three parts: a 5-carbon sugar called deoxyribose, a phosphate group, and a nitrogenous base. 29. Explain how hargaff s observations helped Watson and rick model N. hargaff s observations gave Watson and rick confidence that the base pairing in their model was correct, because their model agreed with hargaff s observations of the relative percentages of, T, G, and in N. 5

6 PRTIE TEST HPTER What important clue from Rosalind Franklin s work helped Watson and rick develop their model of N? The scattering pattern of X-rays sent through a sample of N showed that the molecule was helical and consisted of two strands. 31. Why is it significant that the two strands of N are antiparallel? The two strands are antiparallel, which means that the bases can line up in the two strands and form hydrogen bonds between the T and G pairs. 32. How did Watson and rick s model of the N molecule explain base pairing? The model showed that hydrogen bonds could create a nearly perfect fit between nitrogenous bases along the center of the molecule. Buy the bonds could only form between adenine and thymine, and guanine and cytosine. 33. Rosalind Franklin s X-ray pattern showed that the distance between the two phosphate-sugar backbones of a N molecule is the same throughout the length of the molecule. How did this information help Watson and rick determine how the bases are paired? denine and guanine are larger than cytosine and thymine. The equal distance between the backbones suggested that a small base must always be paired with a large base. 34. What is meant by the term base pairing? How is base pairing involved in N replication? Base pairing is the principle that hydrogen bonds form only between certain base pairs: adenine and thymine, cytosine and guanine. In replication, base pairing ensures that the new complementary strands are identical to the original strands. 6

7 PRTIE TEST HPTER escribe the appearance of N in a typical prokaryotic cell. In a typical prokaryotic cell, N is found in the cytoplasm in a single circular chromosome. 36. Explain the process of replication. When a N molecule is replicated, how do the new molecules compare to the original molecule? N separates into two strands, and then two new complementary strands are generated following the rules of base pairing. Each new N molecule has one strand from the original molecule and one newly synthesized strand, making each new N molecule an exact duplicate of the original. 37. Is photocopying a document similar to N replication? Think of the original materials, the copying process, and the final products. Explain how the two processes are alike. Identify major differences. Photocopying a document is similar in some ways to N replication. In both processes, you start with one copy and end up with two identical copies. However, the copying process is different. In photocopying, the original is copied, so you end up with one completely new copy. In N replication, the original molecule splits in half, so you end up with two copies that are half original and half new. 38. escribe the similarities and differences between N replication in prokaryotic cells and in eukaryotic cells Similarities: N replication in both eukaryotes and prokaryotes proceeds in both directions and results in two identical strands of N. ifferences: prokaryotic N replication occurs in the cytoplasm and begins at a single point on the chromosome; eukaryotic N replication occurs in the nucleus and begins in many places on a chromosome. 39. In their original paper describing the structure of N, Watson and rick noted in a famous sentence that the structure they were proposing immediately suggested how N could make a copy of itself. Explain what Watson and rick meant when they said this. Sample answer: Two stands with paired bases held together by weak hydrogen bonds can be easily pulled apart. new bases lined up on the two strands by base-pairing rules would generate two molecules with the same base sequence. 7

Chapter 11: Molecular Structure of DNA and RNA

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