1. Interest Grabber Order! Genes are made of DNA, a large, complex molecule. DNA is composed of individual units called nucleotides. Three of these units form a code. The order, or sequence, of a code and the type of code determine the meaning of the message. Section 12-1 1. On a sheet of paper, write the word cats. List the letters or units that make up the word cats. 2. Try rearranging the units to form other words. Remember that each new word can have only three units. Write each word on your paper, and then add a definition for each word. 3. Did any of the codes you formed have the same meaning? 4. How do you think changing the order of the nucleotides in the DNA codon changes the codon’s message? Go to Section:

2. Section Outline 12–1DNA A.Griffith and Transformation 1.Griffith’s Experiments 2.Transformation B.Avery and DNA C.The Hershey-Chase Experiment 1.Bacteriophages 2.Radioactive Markers D.The Structure of DNA 1.Chargaff’s Rules 2.X-Ray Evidence 3.The Double Helix Section 12-1 Go to Section:

3. Objectives 1.Be able to define transformation, bacteriophage, nucleotide, and base pairing. 2.Be able to describe the Griffith, Avery, and Hershey-Chase experiments. 3.Be able to explain what scientists discovered about the relationship between genes and DNA. 4.Be able to explain the overall structure of the DNA molecule.

4. Vocabulary Words Transformation – process in which one strain of bacteria is changed by a gene or genes from another strain of bacteria Bacteriophage – a kind of virus that infects and kills bacteria Nucleotide – monomer of nucleic acids made up of a 5-carbon sugar, a phosphate group, and a nitrogenous base Base pairing – principle that bonds in DNA can form only between adenine and thymine and between guanine and cytosine

5. Griffith and Transformation Griffith (mice injected with bacteria) – genetic information could be transformed from one bacterium to another

6. Disease-causing bacteria (smooth colonies) Harmless bacteria (rough colonies) Heat-killed, disease- causing bacteria (smooth colonies) Control (no growth) Heat-killed, disease-causing bacteria (smooth colonies) Harmless bacteria (rough colonies) Dies of pneumoniaLives Live, disease-causing bacteria (smooth colonies) Dies of pneumonia Section 12-1 Figure 12–2 Griffith’s Experiment Go to Section:

7. Disease-causing bacteria (smooth colonies) Harmless bacteria (rough colonies) Heat-killed, disease- causing bacteria (smooth colonies) Control (no growth) Heat-killed, disease-causing bacteria (smooth colonies) Harmless bacteria (rough colonies) Dies of pneumoniaLives Live, disease-causing bacteria (smooth colonies) Dies of pneumonia Section 12-1 Figure 12–2 Griffith’s Experiment Go to Section:

9. Avery and DNA Avery (“juice” from heat-killed bacteria and enzymes) – DNA is the nucleic acid that stores and transmits the genetic information from one generation of an organism to the next

11. Alfred Hershey- Martha Chase Hershey-Chase – genetic material of the bacteriophage is DNA, not protein

12. Bacteriophage with phosphorus-32 in DNA Phage infects bacterium Radioactivity inside bacterium Bacteriophage with sulfur-35 in protein coat Phage infects bacterium No radioactivity inside bacterium Figure 12–4 Hershey-Chase Experiment Section 12-1 Go to Section:

13. Bacteriophage with phosphorus-32 in DNA Phage infects bacterium Radioactivity inside bacterium Bacteriophage with sulfur-35 in protein coat Phage infects bacterium No radioactivity inside bacterium Figure 12–4 Hershey-Chase Experiment Section 12-1 Go to Section:

14. Bacteriophage with phosphorus-32 in DNA Phage infects bacterium Radioactivity inside bacterium Bacteriophage with sulfur-35 in protein coat Phage infects bacterium No radioactivity inside bacterium Figure 12–4 Hershey-Chase Experiment Section 12-1 Go to Section:

15. PurinesPyrimidines AdenineGuanine CytosineThymine Phosphate group Deoxyribose Figure 12–5 DNA Nucleotides Section 12-1 Go to Section:

16. Percentage of Bases in Four Organisms Section 12-1 Source of DNAATGC Streptococcus29.831.620.518.0 Yeast31.332.918.717.1 Herring27.827.522.222.6 Human30.929.419.919.8 Streptococcus29.831.620.518.0 Yeast31.332.918.717.1 Herring27.827.522.222.6 Human30.929.419.919.8 Go to Section:

17. Sugar-Phosphate Backbone and Chargaff’s Rule Chargaff’s Rules: If there are a certain number of cytosines, there will be about the same number of guanines. Same with A’s and T’s.

18. Rosalind Franklin 1950 X-Ray Diffraction Clues from the X-Ray –Coiled (forming Helix) –Double-stranded –Nitrogeneous bases are in the center

19. Watson & Crick Francis Crick – British physicist James Watson – American Biologist –Building a 3D model of DNA –Franklin’s X-Ray opened their eyes to the Double Helix Watson and Crick’s model of DNA was a double helix, in which two strands were wound around each other.

20. Double Helix

21. Hydrogen bonds Nucleotide Sugar-phosphate backbone Key Adenine (A) Thymine (T) Cytosine (C) Guanine (G) Figure 12–7 Structure of DNA Section 12-1 Go to Section:

22. Questions List the conclusions and explain how each of these scientists derived the conclusions: –Griffith –Avery –Hershey and Chase Why did Hershey and Chase grow viruses in cultures that contained both radioactive phosphorus and radioactive sulfur? What might have happened if they only used one? How did Watson and Crick’s model explain why there are equal amounts of thymine and adenine in DNA?

23. Interest Grabber A Perfect Copy When a cell divides, each daughter cell receives a complete set of chromosomes. This means that each new cell has a complete set of the DNA code. Before a cell can divide, the DNA must be copied so that there are two sets ready to be distributed to the new cells. Section 12-2 Go to Section:

24. Interest Grabber continued Section 12-2 1.On a sheet of paper, draw a curving or zig-zagging line that divides the paper into two halves. Vary the bends in the line as you draw it. Without tracing, copy the line on a second sheet of paper. 2.Hold the papers side by side, and compare the lines. Do they look the same? 3.Now, stack the papers, one on top of the other, and hold the papers up to the light. Are the lines the same? 4.How could you use the original paper to draw exact copies of the line without tracing it? 5.Why is it important that the copies of DNA that are given to new daughter cells be exact copies of the original? Go to Section:

25. 12–2Chromosomes and DNA Replication A.DNA and Chromosomes 1.DNA Length 2.Chromosome Structure B.DNA Replication 1.Duplicating DNA 2.How Replication Occurs Section 12-2 Section Outline Go to Section:

26. Chromosome E. coli bacterium Bases on the chromosome Prokaryotic Chromosome Structure Section 12-2 Go to Section: No Nucleus

27. Prokaryote DNA one circular chromosome Most have one circular chromosome located in the cytoplasm with some plasmids (circular DNA molecule found in bacteria) as well –E.Coli (1.6μm diameter) –4,639,221 base pairs 1.6mm long –Like packing 300m of rope in your backpack

28. Eukaryotes and DNA 1000 times more base pairs than bacterial DNA Smallest human chromosome has 30 million base pairs of DNA How do eukaryotes fit all that DNA in its nucleus?

29. Figure 12-10 Chromosome Structure of Eukaryotes Chromosome Supercoils Coils Nucleosome Histones DNA double helix Section 12-2 Go to Section:

30. DNA to Chromosomes Vocabulary –Chromatin - granular material (uncondensed) within the nucleus; consists of DNA tightly coiled around proteins –Chromosomes – condensed chromatin –Histone - globular protein molecule around which DNA is tightly coiled in chromatin

32. DNA Replication During DNA replication, the DNA molecule separates into two strands, then produces two new complementary strands following the rules of base pairing. Each strand of the double helix of DNA serves as a template, or model, for the new strand.

33. Enzymes unwind DNA Enzymes split “unzip” double helix DNA polymerase, The enzyme, DNA polymerase, finds and attaches the corresponding N-base Each “old” stand serves as a template and is matched up with a new stand of DNA New helixes wind back up.

34. Figure 12–11 DNA Replication Section 12-2 Go to Section: Growth Replication fork DNA polymerase New strand Original strand DNA polymerase Nitrogenous bases Replication fork Original strand New strand

35. DNA Replication A – C – T – T – G – G – A – C T – G – A – A – C – C – T - G

36. Interest Grabber Information, Please DNA contains the information that a cell needs to carry out all of its functions. In a way, DNA is like the cell’s encyclopedia. Suppose that you go to the library to do research for a science project. You find the information in an encyclopedia. You go to the desk to sign out the book, but the librarian informs you that this book is for reference only and may not be taken out. Section 12-3 1. Why do you think the library holds some books for reference only? 2. If you can’t borrow a book, how can you take home the information in it? 3. All of the parts of a cell are controlled by the information in DNA, yet DNA does not leave the nucleus. How do you think the information in DNA might get from the nucleus to the rest of the cell? Go to Section:

37. 12–3RNA and Protein Synthesis A.The Structure of RNA B.Types of RNA C.Transcription D.RNA Editing E.The Genetic Code F.Translation G.The Roles of RNA and DNA H.Genes and Proteins Section 12-3 Section Outline Go to Section:

38. fromtoto make up Concept Map Section 12-3 also calledwhich functions toalso called which functions to can be RNA Messenger RNA Ribosomal RNA Transfer RNA mRNACarry instructions rRNA Combine with proteins tRNA Bring amino acids to ribosome DNARibosomeRibosomes Go to Section:

39. RNA and Protein Synthesis Codon - three-nucleotide sequence on messenger RNA that codes for a single amino acid Anticodon - group of three bases on a tRNA molecule that are complementary to an mRNA codon

40. Protein Synthesis: Two Parts Transcription Occurs in the nucleus Formation of a single strand of messenger RNA from DNA Translation Occurs on ribosomes Cell uses the information on mRNA to assemble amino acids in the proper order to form specific proteins

41. Transcription Occurs in nucleus Enzymes unwind DNA Enzymes split “unzip” double helix RNA polymerase binds to promoter sequence (signal) on DNA RNA polymerase transcribes a single strand of mRNA

42. RNA DNA RNA polymerase Figure 12–14 Transcription Section 12-3 Adenine (DNA and RNA) Cystosine (DNA and RNA) Guanine(DNA and RNA) Thymine (DNA only) Uracil (RNA only) Go to Section:

43. Figure 12–17 The Genetic Code Section 12-3 Proteins are made by joining amino acids into long chains called polypeptides. Each polypeptide contains a combination of any or all of the 20 different amino acids. The genetic code shows the amino acid to which each of the 64 possible codons corresponds. There is one codon, AUG, that can either specify methionine, or serve as the initiation, or “start”, for protein synthesis. There are three “stop” codons that do not code for any amino acid.

44. Messenger RNA Messenger RNA is transcribed in the nucleus. Transfer RNA The mRNA then enters the cytoplasm and attaches to a ribosome. Translation begins at AUG, the start codon. Each transfer RNA has an anticodon whose bases are complementary to a codon on the mRNA strand. The ribosome positions the start codon to attract its anticodon, which is part of the tRNA that binds methionine. The ribosome also binds the next codon and its anticodon. mRNA Start codon Ribosome Methionine Phenylalanine tRNA Lysine Nucleus Figure 12–18 Translation Section 12-3 mRNA Go to Section:

45. The Polypeptide “Assembly Line” The ribosome joins the two amino acids— methionine and phenylalanine—and breaks the bond between methionine and its tRNA. The tRNA floats away, allowing the ribosome to bind to another tRNA. The ribosome moves along the mRNA, binding new tRNA molecules and amino acids. mRNA Ribosome Translation direction Lysine tRNA Ribosome Growing polypeptide chain mRNA Completing the Polypeptide The process continues until the ribosome reaches one of the three stop codons. The result is a growing polypeptide chain. Figure 12–18 Translation (continued) Section 12-3 Go to Section:

47. Questions 1. What happens during DNA replication? 2. List and describe the three main types of RNA. 3.Describe the interactions between DNA, RNA, and proteins during each part of protein synthesis? 4. Describe the main difference between RNA and DNA.

48. Interest Grabber Determining the Sequence of a Gene DNA contains the code of instructions for cells. Sometimes, an error occurs when the code is copied. Such errors are called mutations. Section 12-4 Go to Section:

49. Interest Grabber continued Section 12-4 1.Copy the following information about Protein X: Methionine— Phenylalanine—Tryptophan—Asparagine—Isoleucine—STOP. 2.Use Figure 12–17 on page 303 in your textbook to determine one possible sequence of RNA to code for this information. Write this code below the description of Protein X. Below this, write the DNA code that would produce this RNA sequence. 3.Now, cause a mutation in the gene sequence that you just determined by deleting the fourth base in the DNA sequence. Write this new sequence. 4.Write the new RNA sequence that would be produced. Below that, write the amino acid sequence that would result from this mutation in your gene. Call this Protein Y. 5.Did this single deletion cause much change in your protein? Explain your answer. Go to Section:

50. 12–4Mutations A.Gene Mutations B.Chromosomal Mutations Section 12-4 Section Outline Go to Section:

51. Mutations Mutation - change in a DNA sequence that affects genetic information Two Main Types: –Gene Mutation Mutation that causes a change in a single gene –Chromosomal Mutation Mutation that causes a change in an entire chromosome

52. Substitution Insertion Deletion Gene Mutations: Substitution, Insertion, and Deletion Section 12-4 Go to Section:

53. Gene Mutations Point Mutation (substitution) –mutation that affects a single nucleotide, usually by substituting one nucleotide for another Frameshift Mutation (insertion or deletion) –mutation that shifts the “reading” frame of the genetic message by inserting or deleting a nucleotide

54. Deletion Duplication Inversion Translocation Figure 12–20 Chromosomal Mutations Section 12-4 Go to Section: Chromosomal mutations involve changes in whole chromosomes.

55. 12–5Gene Regulation A.Gene Regulation: An Example B.Eukaryotic Gene Regulation C.Regulation and Development Section 12-5 Section Outline Go to Section:

56. Interest Grabber Regulation of Protein Synthesis Every cell in your body, with the exception of gametes, or sex cells, contains a complete copy of your DNA. Why, then, are some cells nerve cells with dendrites and axons, while others are red blood cells that have lost their nuclei and are packed with hemoglobin? Why are cells so different in structure and function? If the characteristics of a cell depend upon the proteins that are synthesized, what does this tell you about protein synthesis? Work with a partner to discuss and answer the questions that follow. Section 12-5 Go to Section:

57. Interest Grabber continued Section 12-5 1.Do you think that cells produce all the proteins for which the DNA (genes) code? Why or why not? How do the proteins made affect the type and function of cells? 2.Consider what you now know about genes and protein synthesis. What might be some ways that a cell has control over the proteins it produces? 3.What type(s) of organic compounds are most likely the ones that help to regulate protein synthesis? Justify your answer. Go to Section:

58. Regulatory sites Promoter (RNA polymerase binding site) Start transcription DNA strand Stop transcription Typical Gene Structure Section 12-5 Go to Section: Regulatory site – places where other proteins, binding directly to the DNA sequences at those sites, can regulate transcription. The actions of these proteins help to determine whether a gene is turned on or turned off. Promoter - region of DNA that indicates to RNA polymerase where to bind to make RNA

59. Lac Operon (E. coli) Operon – a group of genes that act together Operator bound – RNA polymerase can’t transcribe genetic information (not expressed) Operator free – gene(s) expressed Operator - region of chromosome in an operon to which the repressor binds when the operon is “turned off”

60. Eukaryotic Gene Regulation mRNA editing before going to transcription Intron - intervening sequence of DNA; does not code for a protein (not used) Exon - expressed sequence of DNA; codes for a protein (used) TATA box – a short region of DNA about 30 base pairs long; seems to help position RNA polymerase by marking a point just before the point at which transcription begins

61. Eukaryote Gene Regulation DNA region about 30bp long TATATAAA: help to align RNA Polymerase Genes are regulated in a variety of ways by enhancer sequences

62. Gene Regulation Prokaryote Gene Regulation –Will often have one OPERATOR (regulatory site) controlling the expression of more than one gene OPERON Eukaryote Gene Regulation –Most eukaryotic genes are controlled individually and have regulatory sequences that are much more complex than those of the lac operon

63. Gene Reg. and Development hox genes - series of genes that controls the organs and tissues that develop in various parts of an embryo Mutations affecting the hox genes in the fruit fly, Drosophila, for example, can replace the fly’s antennae with a pair of legs growing right out of its head!