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12 1 DNA Griffith and Transformation Griffith and Transformation In 1928, Fredrick Griffith was trying to learn how certain types of bacteria caused

2 12 1 DNA Griffith and Transformation Griffith and Transformation In 1928, Fredrick Griffith was trying to learn how certain types of bacteria caused pneumonia. He isolated two different strains of pneumonia bacteria from mice and grew them in his lab. 2 of 37

3 12 1 DNA Griffith and Transformation Griffith made two observations: (1) The disease-causing strain of bacteria grew into smooth colonies on culture plates. (2) The harmless strain grew into colonies with rough edges. 3 of 37

4 12 1 DNA Griffith's Experiments Griffith set up four individual experiments. Experiment 1: Griffith and Transformation Mice were injected with the disease-causing strain of bacteria. The mice developed pneumonia and died. 4 of 37

5 12 1 DNA Griffith and Transformation Experiment 2: Mice were injected with the harmless strain of bacteria. These mice didn t get sick. Harmless bacteria (rough colonies) Lives 5 of 37

6 12 1 DNA Griffith and Transformation Experiment 3: Griffith heated the disease-causing bacteria. He then injected the heat-killed bacteria into the mice. The mice survived. Heat-killed diseasecausing bacteria (smooth colonies) Lives 6 of 37

7 12 1 DNA Griffith and Transformation Experiment 4: Griffith mixed his heatkilled, disease-causing bacteria with live, harmless bacteria and injected the mixture into the mice. The mice developed pneumonia and died. Live diseasecausing bacteria (smooth colonies) Heat-killed diseasecausing bacteria (smooth colonies) Harmless bacteria (rough colonies) Dies of pneumonia 7 of 37

8 12 1 DNA Griffith and Transformation Griffith concluded the heat-killed bacteria passed their disease-causing ability to the harmless strain. Heat-killed diseasecausing bacteria (smooth colonies) Harmless bacteria (rough colonies) Live diseasecausing bacteria (smooth colonies) Dies of pneumonia 8 of 37

9 12 1 DNA Griffith and Transformation Transformation Griffith called this process transformation because one strain of bacteria (the harmless strain) had changed permanently into another (the disease-causing strain). Griffith hypothesized that a factor must contain information that could change harmless bacteria into disease-causing ones. 9 of 37

Avery and his colleagues made an extract from the heat-killed bacteria that

10 12 1 DNA Avery and DNA Avery and DNA Oswald Avery repeated Griffith s work to determine which molecule was most important for transformation. Avery and his colleagues made an extract from the heat-killed bacteria that they treated with enzymes. 10 of 37

11 12 1 DNA Avery and DNA The enzymes destroyed proteins, lipids, carbohydrates, and other molecules, including the nucleic acid RNA. Transformation still occurred. 11 of 37

12 12 1 DNA Avery and DNA Avery and other scientists repeated the experiment using enzymes that would break down DNA. When DNA was destroyed, transformation did not occur. Therefore, they concluded that DNA was the transforming factor. 12 of 37

13 12 1 DNA Avery and DNA Avery and other scientists discovered that the nucleic acid DNA stores and transmits the genetic information from one generation of an organism to the next. 13 of 37

14 12 1 DNA The Hershey-Chase Experiment The Hershey-Chase Experiment Alfred Hershey and Martha Chase studied viruses nonliving particles smaller than a cell that can infect living organisms. 14 of 37

15 12 1 DNA The Hershey-Chase Experiment Bacteriophages A virus that infects bacteria is known as a bacteriophage. Bacteriophages are composed of a DNA or RNA core and a protein coat. 15 of 37

16 12 1 DNA The Hershey-Chase Experiment They grew viruses in cultures containing radioactive isotopes of phosphorus-32 ( 32 P) and sulfur-35 ( 35 S) of 37

17 12 1 DNA The Hershey-Chase Experiment If 35 S was found in the bacteria, it would mean that the viruses protein had been injected into the bacteria. 17 of 37

18 12 1 DNA The Hershey-Chase Experiment If 32 P was found in the bacteria, then it was the DNA that had been injected. Bacteriophage with phosphorus-32 in DNA Phage infects bacterium Radioactivity inside bacterium 18 of 37

19 12 1 DNA The Hershey-Chase Experiment Nearly all the radioactivity in the bacteria was from phosphorus ( 32 P). Hershey and Chase concluded that the genetic material of the bacteriophage was DNA, not protein. 19 of 37

20 12 1 DNA The Components and Structure of DNA The Components and Structure of DNA DNA is made up of nucleotides. A nucleotide is a monomer of nucleic acids made up of: Deoxyribose 5-carbon Sugar Phosphate Group Nitrogenous Base 20 of 37

21 12 1 DNA The Components and Structure of DNA There are four kinds of bases in in DNA: adenine guanine cytosine thymine 21 of 37

22 12 1 DNA The Components and Structure of DNA Chargaff's Rules Erwin Chargaff discovered that: The percentages of guanine [G] and cytosine [C] bases are almost equal in any sample of DNA. The percentages of adenine [A] and thymine [T] bases are almost equal in any sample of DNA of 37

$used X-ray diffraction to get information about the structure of DNA.$ She aimed an X-ray beam at concentrated DNA samples and recorded the scattering

She aimed an X-ray beam at concentrated DNA samples and recorded the scattering

23 12 1 DNA The Components and Structure of DNA X-Ray Evidence Rosalind Franklin used X-ray diffraction to get information about the structure of DNA. She aimed an X-ray beam at concentrated DNA samples and recorded the scattering pattern of the X-rays on film. 23 of 37

24 12 1 DNA The Components and Structure of DNA The Double Helix Using clues from Franklin s pattern, James Watson and Francis Crick built a model that explained how DNA carried information and could be copied. Watson and Crick's model of DNA was a double helix, in which two strands were wound around each other. 24 of 37

25 12 1 DNA DNA Double Helix The Components and Structure of DNA 25 of 37

26 12 1 DNA The Components and Structure of DNA Watson and Crick discovered that hydrogen bonds can form only between certain base pairs adenine and thymine, and guanine and cytosine. This principle is called base pairing. 26 of 37

27 12 1 DNA REVIEW CONTENT 27 of 37

28 12 1 Avery and other scientists discovered that a. DNA is found in a protein coat. b. DNA stores and transmits genetic information from one generation to the next. c. transformation does not affect bacteria. d. proteins transmit genetic information from one generation to the next. 28 of 37

29 12 1 The Hershey-Chase experiment was based on the fact that a. DNA has both sulfur and phosphorus in its structure. b. protein has both sulfur and phosphorus in its structure. c. both DNA and protein have no phosphorus or sulfur in their structure. d. DNA has only phosphorus, while protein has only sulfur in its structure. 29 of 37

30 12 1 DNA is a long molecule made of monomers called a. nucleotides. b. purines. c. pyrimidines. d. sugars. 30 of 37

31 12 1 Chargaff's rules state that the number of guanine nucleotides must equal the number of a. cytosine nucleotides. b. adenine nucleotides. c. thymine nucleotides. d. thymine plus adenine nucleotides. 31 of 37

32 12 1 In DNA, the following base pairs occur: a. A with C, and G with T. b. A with T, and C with G. c. A with G, and C with T. d. A with T, and C with T. 32 of 37

33 12 2 Chromosomes and DNA Replication 12-2 Chromosomes and DNA Replication 33 of 37

34 DNA and Chromosomes DNA and Chromosomes In prokaryotic cells, DNA is located in the cytoplasm. Most prokaryotes have a single DNA molecule containing nearly all of the cell s genetic information. 34 of 37

35 DNA and Chromosomes Chromosome E. Coli Bacterium Bases on the Chromosomes 35 of 37

36 DNA and Chromosomes Many eukaryotes have 1000 times the amount of DNA as prokaryotes. Eukaryotic DNA is located in the cell nucleus inside chromosomes. The number of chromosomes varies widely from one species to the next. 36 of 37

37 DNA and Chromosomes Chromosome Structure Eukaryotic chromosomes contain DNA and protein, tightly packed together to form chromatin. Chromatin consists of DNA tightly coiled around proteins called histones. DNA and histone molecules form nucleosomes. Nucleosomes pack together, forming a thick fiber. 37 of 37

38 DNA and Chromo somes Eukaryotic Chromosome Structure Chromosome Nucleosome DNA double helix Supercoils Coils Histones 38 of 37

39 DNA Replication DNA Replication Each strand of the DNA double helix has all the information needed to reconstruct the other half by the mechanism of base pairing. In most prokaryotes, DNA replication begins at a single point and continues in two directions. 39 of 37

40 DNA Replication In eukaryotic chromosomes, DNA replication occurs at hundreds of places. Replication proceeds in both directions until each chromosome is completely copied. The sites where separation and replication occur are called replication forks. 40 of 37

41 DNA Replication Duplicating DNA Before a cell divides, it duplicates its DNA in a process called replication. Replication ensures that each resulting cell will have a complete set of DNA. 41 of 37

42 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 for the new strand. 42 of 37

43 DNA Replication New Strand Original strand Nitrogen Bases Growth Growth Replication Fork Replication Fork DNA Polymerase 43 of 37

44 DNA Replication How Replication Occurs DNA replication is carried out by enzymes that unzip a molecule of DNA. Hydrogen bonds between base pairs are broken and the two strands of DNA unwind. 44 of 37

45 DNA Replication The principal enzyme involved in DNA replication is DNA polymerase. DNA polymerase joins individual nucleotides to produce a DNA molecule and then proofreads each new DNA strand. 45 of 37

46 12 2 In prokaryotic cells, DNA is found in the a. cytoplasm. b. nucleus. c. ribosome. d. cell membrane. 46 of 37

47 12 2 The first step in DNA replication is a. producing two new strands. b. separating the strands. c. producing DNA polymerase. d. correctly pairing bases. 47 of 37

48 12 2 A DNA molecule separates, and the sequence GCGAATTCG occurs in one strand. What is the base sequence on the other strand? a. GCGAATTCG b. CGCTTAAGC c. TATCCGGAT d. GATGGCCAG 48 of 37

49 12 2 In addition to carrying out the replication of DNA, the enzyme DNA polymerase also functions to a. unzip the DNA molecule. b. regulate the time copying occurs in the cell cycle. c. proofread the new copies to minimize the number of mistakes. d. wrap the new strands onto histone proteins. 49 of 37

50 12 2 The structure that may play a role in regulating how genes are read to make a protein is the a. coil. b. histone. c. nucleosome. d. chromatin. 50 of 37

51 12-3 RNA and Protein Synthesi 12 3 RNA and Protein Synthesis 51 of 37

52 12 3 RNA and Protein Synthesis Genes are coded DNA instructions that control the production of proteins. Genetic messages can be decoded by copying part of the nucleotide sequence from DNA into RNA. RNA contains coded information for making proteins of 37

53 The Structure of RNA The Structure of RNA There are three main differences between RNA and DNA: a. The sugar in RNA is ribose instead of deoxyribose. b. RNA is generally single-stranded. c. RNA contains uracil in place of thymine. 53 of 37

54 Types of RNA Types of RNA There are three main types of RNA: a. messenger RNA b. ribosomal RNA c. transfer RNA 54 of 37

55 Types of RNA Messenger RNA (mrna) carries copies of instructions for assembling amino acids into proteins. 55 of 37

56 Types of RNA Ribosomes are made up of proteins and ribosomal RNA (rrna). 56 of 37

57 Amino acid Types of RNA Transfer RNA During protein construction, transfer RNA (trna) transfers each amino acid to the ribosome. 57 of 37

58 DNA molecule DNA strand (template) 3 5 TRANSCRIPTION mrna 5 3 Codon TRANSLATION Protein 58 of 37 Amino acid

59 Transcription DNA is copied in the form of RNA This first process is called transcription. The process begins at a section of DNA called a promoter. 59 of 37

60 Transcription RNA RNA polymerase DNA 60 of 37

61 RNA Editing RNA Editing Some DNA within a gene is not needed to produce a protein. These areas are called introns. The DNA sequences that code for proteins are called exons. 61 of 37

62 RNA Editing The introns are cut out of RNA molecules. The exons are the spliced together to form mrna. Exon Intron DNA Pre-mRNA mrna Cap Tail 62 of 37

63 The Genetic Code The Genetic Code The genetic code is the language of mrna instructions. The code is written using four letters (the bases: A, U, C, and G). 63 of 37

64 A codon consists of three consecutive nucleotides on mrna that specify a particular amino acid. The Genetic Code 64 of 37

65 The Genetic Code 65 of 37

66 Translation Translation Translation is the decoding of an mrna message into a polypeptide chain (protein). Translation takes place on ribosomes. During translation, the cell uses information from messenger RNA to produce proteins. Nucleus mrna 66 of 37

67 The ribosome binds new trna molecules and amino acids as it moves along the mrna. Phenylalanine Lysine trna Methionine Translation Ribosome mrna Start codon 67 of 37

68 Translation Protein Synthesis Lysine trna mrna Ribosome Translation direction 68 of 37

69 The process continues until the ribosome reaches a stop codon. Polypeptide Translation trna Ribosome mrna 69 of 37

70 GENES AND PROTIEN DNA Codon Codon Codon Single strand of DNA Codon Codon Codon mrna mrna Protein Alanine Arginine Leucine Amino acids within a polypeptide 70 of 37

71 12 3 The role of a master plan in a building is similar to the role of which molecule? a. messenger RNA b. DNA c. transfer RNA d. ribosomal RNA 71 of 37

72 12 3 A base that is present in RNA but NOT in DNA is a. thymine. b. uracil. c. cytosine. d. adenine. 72 of 37

73 12 3 The nucleic acid responsible for bringing individual amino acids to the ribosome is a. transfer RNA. b. DNA. c. messenger RNA. d. ribosomal RNA. 73 of 37

74 12 3 A region of a DNA molecule that indicates to an enzyme where to bind to make RNA is the a. intron. b. exon. c. promoter. d. codon. 74 of 37

75 12 3 A codon typically carries sufficient information to specify a(an) a. single base pair in RNA. b. single amino acid. c. entire protein. d. single base pair in DNA. 75 of 37

76 12 4 Mutations 12-4 Mutations 76 of 37

77 Kinds of Mutations Mutations are changes in the genetic material. Kinds of Mutations Mutations that produce changes in a single gene are known as gene mutations. Mutations that produce changes in whole chromosomes are known as chromosomal mutations. 77 of 37

78 Kinds of Mutations Gene Mutations Gene mutations involving a change in one or a few nucleotides are known as point mutations because they occur at a single point in the DNA sequence. Point mutations include substitutions, insertions, and deletions. 78 of 37

79 Kinds of Mutations Substitutions usually affect no more than a single amino acid. 79 of 37

80 Kinds of Mutations The effects of insertions or deletions are more dramatic. The addition or deletion of a nucleotide causes a shift in the grouping of codons. Changes like these are called frameshift mutations. 80 of 37

81 Kinds of Mutations In an insertion, an extra base is inserted into a base sequence. 81 of 37

82 Kinds of Mutations In a deletion, the loss of a single base is deleted and the reading frame is shifted. 82 of 37

83 Kinds of Mutations Chromosomal Mutations Chromosomal mutations involve changes in the number or structure of chromosomes. Chromosomal mutations include deletions, duplications, inversions, and translocations. 83 of 37

84 Kinds of Mutations Deletions involve the loss of all or part of a chromosome. 84 of 37

85 Kinds of Mutations Duplications produce extra copies of parts of a chromosome. 85 of 37

86 Kinds of Mutations Inversions reverse the direction of parts of chromosomes. 86 of 37

87 Kinds of Mutations Translocations occurs when part of one chromosome breaks off and attaches to another. 87 of 37

88 Significance of Mutations Significance of Mutations Many mutations have little or no effect on gene expression. Some mutations are the cause of genetic disorders. Polyploidy is the condition in which an organism has extra sets of chromosomes. 88 of 37

89 12 4 A mutation in which all or part of a chromosome is lost is called a(an) a. duplication. b. deletion. c. inversion. d. point mutation. 89 of 37

90 12 4 A mutation that affects every amino acid following an insertion or deletion is called a(an) a. frameshift mutation. b. point mutation. c. chromosomal mutation. d. inversion. 90 of 37

91 12 4 A mutation in which a segment of a chromosome is repeated is called a(an) a. deletion. b. inversion. c. duplication. d. point mutation. 91 of 37

92 12 4 The type of point mutation that usually affects only a single amino acid is called a. a deletion. b. a frameshift mutation. c. an insertion. d. a substitution. 92 of 37

93 12 4 When two different chromosomes exchange some of their material, the mutation is called a(an) a. inversion. b. deletion. c. substitution. d. translocation. 93 of 37

94 12-5 Gene Regulation Fruit fly chromosome Mouse chromosomes 12-5 Gene Regulation Fruit fly embryo Mouse embryo Adult fruit fly Adult mouse 94 of 37

95 Gene Regulation: An Example Gene Regulation: An Example a. E. coli provides an example of how gene expression can be regulated. b. An operon is a group of genes that operate together. c. In E. coli, these genes must be turned on so the bacterium can use lactose as food. d. Therefore, they are called the lac operon. 95 of 37

96 Gene Regulation: An Example How are lac genes turned off and on? 96 of 37

97 Gene Regulation: An Example The lac genes are turned off by repressors and turned on by the presence of lactose. 97 of 37

98 Gene Regulation: An Example On one side of the operon's three genes are two regulatory regions. a. In the promoter (P) region, RNA polymerase binds and then begins transcription. 98 of 37

99 Gene Regulation: An Example a. The other region is the operator (O). 99 of 37

100 Gene Regulation: An Example When the lac repressor binds to the O region, transcription is not possible. 100 of 37

101 Gene Regulation: An Example When lactose is added, sugar binds to the repressor proteins. 101 of 37

102 Gene Regulation: An Example The repressor protein changes shape and falls off the operator and transcription is made possible. 102 of 37

103 Gene Regulation: An Example Many genes are regulated by repressor proteins. Some genes use proteins that speed transcription. Sometimes regulation occurs at the level of protein synthesis. 103 of 37

104 Eukaryotic Gene Regulation How are most eukaryotic genes controlled? 104 of 37

105 Eukaryotic Gene Regulation Eukaryotic Gene Regulation Operons are generally not found in eukaryotes. Most eukaryotic genes are controlled individually and have regulatory sequences that are much more complex than those of the lac operon. 105 of 37

106 Eukaryotic Gene Regulation Many eukaryotic genes have a sequence called the TATA box. Upstream enhancer TATA box Introns Promoter sequences Exons Direction of transcription 106 of 37

107 Eukaryotic Gene Regulation The TATA box seems to help position RNA polymerase. Upstream enhancer TATA box Introns Promoter sequences Exons Direction of transcription 107 of 37

108 Eukaryotic Gene Regulation Eukaryotic promoters are usually found just before the TATA box, and consist of short DNA sequences. Upstream enhancer TATA box Introns Promoter sequences Exons Direction of transcription 108 of 37

109 Eukaryotic Gene Regulation Genes are regulated in a variety of ways by enhancer sequences. Many proteins can bind to different enhancer sequences. Some DNA-binding proteins enhance transcription by: a. opening up tightly packed chromatin b. helping to attract RNA polymerase c. blocking access to genes. 109 of 37

110 Development and Differentiation Development and Differentiation a. As cells grow and divide, they undergo differentiation, meaning they become specialized in structure and function. b. Hox genes control the differentiation of cells and tissues in the embryo. 110 of 37

111 Development and Differentiation Careful control of expression in hox genes is essential for normal development. All hox genes are descended from the genes of common ancestors. 111 of 37

112 Development and Differentiation Hox Genes Fruit fly chromosome Mouse chromosomes Fruit fly embryo Mouse embryo Adult fruit fly Adult mouse 112 of 37

113 12 5 Which sequence shows the typical organization of a single gene site on a DNA strand? a. start codon, regulatory site, promoter, stop codon b. regulatory site, promoter, start codon, stop codon c. start codon, promoter, regulatory site, stop codon d. promoter, regulatory site, start codon, stop codon 113 of 37

114 12 5 A group of genes that operates together is a(an) a. promoter. b. operon. c. operator. d. intron. 114 of 37

115 12 5 Repressors function to a. turn genes off. b. produce lactose. c. turn genes on. d. slow cell division. 115 of 37

116 12 5 Which of the following is unique to the regulation of eukaryotic genes? a. promoter sequences b. TATA box c. different start codons d. regulatory proteins 116 of 37

117 12 5 Organs and tissues that develop in various parts of embryos are controlled by a. regulation sites. b. RNA polymerase. c. hox genes. d. DNA polymerase. 117 of 37

Summary 12 1 DNA RNA and Protein Synthesis Chromosomes and DNA Replication. Name Class Date

Summary 12 1 DNA RNA and Protein Synthesis Chromosomes and DNA Replication. Name Class Date Chapter 12 Summary DNA and RNA 12 1 DNA To understand genetics, biologists had to learn the chemical structure of the gene. Frederick Griffith first learned that some factor from dead, disease-causing