2. Click on a lesson name to select. FROM DNA TO PROTEINS Section 1: DNA: The Genetic Material Section 2: Replication of DNA Section 3: DNA, RNA, and Protein Section 4: Gene Regulation and Mutation

3. DNA: The Genetic Material Section 1 Griffith  Performed the first major experiment that led to the discovery of DNA as the genetic material

4. Avery  Identified the molecule that transformed the R strain of bacteria into the S strain  Concluded that when the S cells were killed, DNA was released  R bacteria incorporated this DNA into their cells and changed into S cells. DNA: The Genetic Material Section 1

5. Hershey and Chase  Used radioactive labeling to trace the DNA and protein  Concluded that the viral DNA was injected into the cell and provided the genetic information needed to produce new viruses DNA: The Genetic Material Section 1

6. DNA Structure  Nucleotides  Consist of a five-carbon sugar, a phosphate group, and a nitrogenous base DNA: The Genetic Material Section 1

7. Chargaff  Chargaff’s rule: C = G and T = A DNA: The Genetic Material Section 1

8. X-ray Diffraction  X-ray diffraction data helped solve the structure of DNA  Indicated that DNA was a double helix DNA: The Genetic Material Section 1

9. Watson and Crick  Built a model of the double helix that conformed to the others’ research 1. two outside strands consist of alternating deoxyribose and phosphate 2. cytosine and guanine bases pair to each other by three hydrogen bonds 3. thymine and adenine bases pair to each other by two hydrogen bonds DNA: The Genetic Material Section 1

10. Molecular Genetics DNA Structure  DNA often is compared to a twisted ladder.  Rails of the ladder are represented by the alternating deoxyribose and phosphate.  The pairs of bases (cytosine–guanine or thymine–adenine) form the steps. DNA: The Genetic Material Section 1

11. Orientation  On the top rail, the strand is said to be oriented 5′ to 3′.  The strand on the bottom runs in the opposite direction and is oriented 3′ to 5′. DNA: The Genetic Material Section 1

12. DNA: The Genetic Material Chromosome Structure  DNA coils around histones to form nucleosomes, which coil to form chromatin fibers.  The chromatin fibers supercoil to form chromosomes that are visible in the metaphase stage of mitosis. Section 1

13. Replication of DNA Semiconservative Replication  Parental strands of DNA separate, serve as templates, and produce DNA molecules that have one strand of parental DNA and one strand of new DNA. Section 2

14. Unwinding  DNA helicase, an enzyme, is responsible for unwinding and unzipping the double helix.  RNA primase adds a short segment of RNA, called an RNA primer, on each DNA strand. Replication of DNA Section 2

15. Base pairing  DNA polymerase continues adding appropriate nucleotides to the chain by adding to the 3′ end of the new DNA strand. Replication of DNA Section 2

16.  One strand is called the leading strand and is elongated as the DNA unwinds.  The other strand of DNA, called the lagging strand, elongates away from the replication fork.  The lagging strand is synthesized discontinuously into small segments, called Okazaki fragments. Replication of DNA Section 2

17. Joining  DNA polymerase removes the RNA primer and fills in the place with DNA nucleotides.  DNA ligase links the two sections. Replication of DNA Section 2

18. Replication of DNA Comparing DNA Replication in Eukaryotes and Prokaryotes  Eukaryotic DNA unwinds in multiple areas as DNA is replicated.  In prokaryotes, the circular DNA strand is opened at one origin of replication. Section 2

19. DNA, RNA, and Protein Central Dogma – Information flows in one dirrection, from DNA to RNA(Francis Crick)  RNA  Contains the sugar ribose and the base uracil instead of thymine  Usually is single stranded Section 3

20. Messenger RNA (mRNA)  Long strands of RNA nucleotides that are formed complementary to one strand of DNA Ribosomal RNA (rRNA)  Associates with proteins to form ribosomes in the cytoplasm Transfer RNA (tRNA)  Smaller segments of RNA nucleotides that transport amino acids to the ribosome DNA, RNA, and Protein Section 3

21.  DNA is unzipped in the nucleus and RNA polymerase binds to a specific section where an mRNA will be synthesized. Transcription  Through transcription, the DNA code is transferred to mRNA in the nucleus. DNA, RNA, and Protein Section 3

22. RNA Processing  The code on the DNA is interrupted periodically by sequences that are not in the final mRNA.  Intervening sequences are called introns.  Remaining pieces of DNA that serve as the coding sequences are called exons. DNA, RNA, and Protein Section 3

23. The Code  Experiments during the 1960s demonstrated that the DNA code was a three-base code.  The three-base code in DNA or mRNA is called a codon. DNA, RNA, and Protein Section 3

24. Translation  In translation, tRNA molecules act as the interpreters of the mRNA codon sequence.  At the middle of the folded strand, there is a three-base coding sequence called the anticodon.  Each anticodon is complementary to a codon on the mRNA. DNA, RNA, and Protein Section 3

25. DNA, RNA, and Protein Section 3

26. DNA, RNA, and Protein One Gene— One Enzyme  The Beadle and Tatum experiment showed that one gene codes for one enzyme. We now know that one gene codes for one polypeptide. Section 3

27. Gene Regulation and Mutation Prokaryote Gene Regulation  Ability of an organism to control which genes are transcribed in response to the environment  An operon is a section of DNA that contains the genes for the proteins needed for a specific metabolic pathway.  Operator  Promoter  Regulatory gene  Genes coding for proteins Section 4

28. The Trp Operon Gene Regulation and Mutation Section 4

29. The Lac Operon Gene Regulation and Mutation Section 4

30. Eukaryote Gene Regulation  Controlling transcription  Transcription factors ensure that a gene is used at the right time and that proteins are made in the right amounts  The complex structure of eukaryotic DNA also regulates transcription. Gene Regulation and Mutation Section 4

31. RNA Interference  RNA interference can stop the mRNA from translating its message. Gene Regulation and Mutation Section 4

32. Mutations  A permanent change that occurs in a cell’s DNA is called a mutation.  Types of mutations  Point mutation  Insertion  Deletion Gene Regulation and Mutation Section 4

33. Gene Regulation and Mutation Section 4

34. Protein Folding and Stability  Substitutions also can lead to genetic disorders.  Can change both the folding and stability of the protein Gene Regulation and Mutation Section 4

35. Causes of Mutation  Can occur spontaneously  Chemicals and radiation also can damage DNA.  High-energy forms of radiation, such as X rays and gamma rays, are highly mutagenic. Gene Regulation and Mutation Section 4

36. Body-cell v. Sex-cell Mutation  Somatic cell mutations are not passed on to the next generation.  Mutations that occur in sex cells are passed on to the organism’s offspring and will be present in every cell of the offspring. Gene Regulation and Mutation Section 4

37. 1.A 2.B 3.C 4.D CDQ 1 A. Watson and Crick B. Mendel C. Hershey and Chase D. Avery Which scientist(s) definitively proved that DNA transfers genetic material? Molecular Genetics Chapter Diagnostic Questions Chapter

38. 1.A 2.B 3.C 4.D CDQ 2 Molecular Genetics Chapter Diagnostic Questions Chapter A. ligase B. Okazaki fragments C. micro RNA D. helicase Name the small segments of the lagging DNA strand.

39. 1.A 2.B 3.C 4.D CDQ 3 Molecular Genetics Chapter Diagnostic Questions Chapter A. It contains the sugar ribose. B. It contains the base uracil. C. It is single-stranded. D. It contains a phosphate. Which is not true of RNA?

40. 1.A 2.B 3.C 4.D FQ 1 Molecular Genetics Chapter A. carbohydrate B. DNA C. lipid D. protein The experiments of Avery, Hershey and Chase provided evidence that the carrier of genetic information is _______. Section 1 Formative Questions

41. 1.A 2.B 3.C 4.D FQ 2 Molecular Genetics Chapter A. A—G and C—T B. A—T and C—G C. C—A and G—T D. C—U and A—G What is the base-pairing rule for purines and pyrimidines in the DNA molecule? Section 1 Formative Questions

42. 1.A 2.B 3.C 4.D FQ 3 Molecular Genetics Chapter Section 1 Formative Questions A.chromatin and histones B. DNA and protein C. DNA and lipids D. protein and centromeres What are chromosomes composed of?

43. 1.A 2.B FQ 4 Molecular Genetics Chapter The work of Watson and Crick solved the mystery of how DNA works as a genetic code. A. True B. False Section 2 Formative Questions

44. 1.A 2.B 3.C 4.D FQ 5 Molecular Genetics Chapter Section 2 Formative Questions A. DNA ligase B. DNA polymerase C. hilicase D. RNA primer Which is not an enzyme involved in DNA replication?

45. 1.A 2.B 3.C 4.D FQ 6 Molecular Genetics Chapter Which shows the basic chain of events in all organisms for reading and expressing genes? A. DNA  RNA  protein B. RNA  DNA  protein C. mRNA  rRNA  tRNA D. RNA processing  transcription  translation Section 3 Formative Questions

46. 1.A 2.B 3.C 4.D FQ 7 Molecular Genetics Chapter Section 3 Formative Questions In the RNA molecule, uracil replaces _______. A. adenine B. cytosine C. purine D. thymine

47. 1.A 2.B 3.C 4.D FQ 8 Molecular Genetics Chapter Section 3 Formative Questions Which diagram shows messenger RNA (mRNA)? A. C. B. D.

48. 1.A 2.B 3.C 4.D FQ 9 Molecular Genetics Chapter Section 3 Formative Questions What characteristic of the mRNA molecule do scientists not yet understand? A.intervening sequences in the mRNA molecule called introns B.the original mRNA made in the nucleus called the pre-mRNA C.how the sequence of bases in the mRNA molecule codes for amino acids D.the function of many adenine nucleotides at the 5′ end called the poly-A tail

49. 1.A 2.B 3.C 4.D FQ 10 Molecular Genetics Chapter Why do eukaryotic cells need a complex control system to regulate the expression of genes? A.All of an organism’s cells transcribe the same genes. B.Expression of incorrect genes can lead to mutations. C.Certain genes are expressed more frequently than others are. D.Different genes are expressed at different times in an organism’s lifetime. Section 4 Formative Questions

50. 1.A 2.B 3.C 4.D FQ 11 Molecular Genetics Chapter Section 4 Formative Questions Which type of gene causes cells to become specialized in structure in function? A. exon B. Hox gene C. intron D. operon

51. 1.A 2.B 3.C 4.D FQ 12 Molecular Genetics Chapter Section 4 Formative Questions What is an immediate result of a mutation in a gene? A. cancer B. genetic disorder C. nonfunctional enzyme D. amino acid deficiency

52. 1.A 2.B 3.C 4.D FQ 13 Molecular Genetics Chapter Section 4 Formative Questions Which is the most highly mutagenic? A. chemicals in food B. cigarette smoke C. ultraviolet radiation D. X rays

53. 1.A 2.B 3.C 4.D CAQ 1 Molecular Genetics Chapter Look at the following figure. Identify the proteins that DNA first coils around. Chapter Assessment Questions A. chromatin fibers B. chromosomes C. histones D. nucleosome

54. Explain the difference between body-cell and sex-cell mutation. Molecular Genetics Chapter Assessment Questions Chapter Answer: A mutagen in a body cell becomes part of the of the genetic sequence in that cell and in future daughter cells. The cell may die or simply not perform its normal function. These mutations are not passed on to the next generation. When mutations occur in sex cells, they will be present in every cell of the offspring. CAQ 3

55. 1.A 2.B 3.C 4.D STP 1 Molecular Genetics Chapter What does this diagram show about the replication of DNA in eukaryotic cells? Standardized Test Practice A. DNA is replicated only at certain places along the chromosome. B. DNA replication is both semicontinuous and conservative. C. Multiple areas of replication occur along the chromosome at the same time. D. The leading DNA strand is synthesized discontinuously.

56. 1.A 2.B 3.C 4.D STP 2 Molecular Genetics Chapter Standardized Test Practice A. mRNA processing B. protein synthesis C. transcription D. translation What is this process called?

57. 1.A 2.B 3.C 4.D STP 3 Molecular Genetics Chapter Standardized Test Practice What type of mutation results in this change in the DNA sequence? A. deletion B. frameshift C. insertion D. substitution TTCAGG TTCTGG

58. 1.A 2.B 3.C 4.D STP 4 Molecular Genetics Chapter Standardized Test Practice How could RNA interference be used to treat diseases such as cancer and diabetes? A.by activating genes to produce proteins that can overcome the disease B.by interfering with DNA replication in cells affected by the disease C.by preventing the translation of mRNA into the genes associated with the disease D.by shutting down protein synthesis in the cells of diseased tissues

59. 1.A 2.B STP 5 Molecular Genetics Chapter Standardized Test Practice The structure of a protein can be altered dramatically by the exchange of a single amino acid for another. A. True B. False