2. Chapter 12 Molecular Genetics
Section 1: DNA: The Genetic Material
Section 2: Replication of DNA
Section 3: DNA, RNA, and Protein
Section 4: Gene Regulation and Mutation

3. Chapter 12
Molecular Genetics
12.1 DNA: The Genetic Material
Griffith
Performed the first major experiment that led to the discovery of DNA as the genetic material

4. Concluded that when the S cells were killed, DNA was released
Chapter 12
Molecular Genetics
12.1 DNA: The Genetic Material
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.

5. Used radioactive labeling to trace the DNA and protein
Chapter 12
Molecular Genetics
12.1 DNA: The Genetic Material
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

6. Chapter 12
Molecular Genetics

7. 12.1 DNA: The Genetic Material
Chapter 12
Molecular Genetics
12.1 DNA: The Genetic Material
DNA Structure
Nucleotides
Consist of a five-carbon sugar, a phosphate group, and a nitrogenous base

8. Chapter 12
Molecular Genetics

9. Chargaff’s rule: C = G and T = A
Chapter 12
Molecular Genetics
12.1 DNA: The Genetic Material
Chargaff
Chargaff’s rule: C = G and T = A

10. X-ray diffraction data helped solve the structure of DNA
Chapter 12
Molecular Genetics
12.1 DNA: The Genetic Material
X-ray Diffraction
X-ray diffraction data helped solve the structure of DNA
Indicated that DNA was a double helix

11. two outside strands consist of alternating deoxyribose and phosphate
Chapter 12
Molecular Genetics
12.1 DNA: The Genetic Material
Watson and Crick
Built a model of the double helix that conformed to the others’ research
two outside strands consist of alternating
deoxyribose and phosphate
cytosine and guanine bases pair to each
other by three hydrogen bonds
thymine and adenine bases pair to each
other by two hydrogen bonds

12. DNA often is compared to a twisted ladder.
Chapter 12
Molecular Genetics
12.1 DNA: The Genetic Material
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.

13. 12.1 DNA: The Genetic Material
Chapter 12
Molecular Genetics
12.1 DNA: The Genetic Material
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′.

14. 12.1 DNA: The Genetic Material
Chapter 12
Molecular Genetics
12.1 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.

15. Semiconservative Replication
Chapter 12
Molecular Genetics
12.2 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.

16. Chapter 12
Molecular Genetics
12.2 Replication of DNA
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.

17. Chapter 12
Molecular Genetics
12.2 Replication of DNA
Base pairing
DNA polymerase continues adding appropriate nucleotides to the chain by adding to the 3′ end of the new DNA strand.

18. Chapter 12
Molecular Genetics

19. Chapter 12
Molecular Genetics
12.2 Replication of DNA
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.

20. DNA ligase links the two sections.
Chapter 12
Molecular Genetics
12.2 Replication of DNA
Joining
DNA polymerase removes the RNA primer and fills in the place with DNA nucleotides.
DNA ligase links the two sections.

21. Comparing DNA Replication in Eukaryotes and Prokaryotes
Chapter 12
Molecular Genetics
12.2 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.

22. Contains the sugar ribose and the base uracil
Chapter 12
Molecular Genetics
12.3 DNA, RNA, and Protein
Central Dogma
RNA
Contains the sugar ribose and the base uracil
Usually is single stranded

23. Associates with proteins to form ribosomes in the cytoplasm
Chapter 12
Molecular Genetics
12.3 DNA, RNA, and Protein
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

24. Chapter 12
Molecular Genetics
12.3 DNA, RNA, and Protein

25. Chapter 12
Molecular Genetics

26. DNA is unzipped in the nucleus and RNA
Chapter 12
Molecular Genetics
12.3 DNA, RNA, and Protein
Transcription
Through transcription, the DNA code is transferred to mRNA in the nucleus.
DNA is unzipped in the nucleus and RNA
polymerase binds to a specific section where an
mRNA will be synthesized.

27. Chapter 12
Molecular Genetics

28. Intervening sequences are called introns.
Chapter 12
Molecular Genetics
12.3 DNA, RNA, and Protein
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 and Genes

29. The three-base code in DNA or mRNA is called a codon.
Chapter 12
Molecular Genetics
12.3 DNA, RNA, and Protein
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.

30. Each anticodon is complementary to a codon on the mRNA.
Chapter 12
Molecular Genetics
12.3 DNA, RNA, and Protein
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.

31. Chapter 12
Molecular Genetics
12.3 DNA, RNA, and Protein

32. Chapter 12
Molecular Genetics

33. Chapter 12
Molecular Genetics
12.3 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.

34. Prokaryote Gene Regulation
Chapter 12
Molecular Genetics
12.4 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

35. The Trp Operon 12.4 Gene Regulation and Mutation Chapter 12
Molecular Genetics
12.4 Gene Regulation and Mutation
The Trp Operon

36. The Lac Operon 12.4 Gene Regulation and Mutation Chapter 12
Molecular Genetics
12.4 Gene Regulation and Mutation
The Lac Operon
Lac-Trp Operon

37. Chapter 12
Molecular Genetics

38. Eukaryote Gene Regulation
Chapter 12
Molecular Genetics
12.4 Gene Regulation and Mutation
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.

39. Chapter 12
Molecular Genetics
12.4 Gene Regulation and Mutation
Hox Genes
Hox genes are responsible for the general body pattern of most animals.

40. RNA interference can stop the mRNA from translating its message.
Chapter 12
Molecular Genetics
12.4 Gene Regulation and Mutation
RNA Interference
RNA interference can stop the mRNA from translating its message.

41. A permanent change that occurs in a cell’s DNA is called a mutation.
Chapter 12
Molecular Genetics
12.4 Gene Regulation and Mutation
Mutations
A permanent change that occurs in a cell’s DNA is called a mutation.
Types of mutations
Point mutation
Insertion
Deletion

42. 12.4 Gene Regulation and Mutation
Chapter 12
Molecular Genetics
12.4 Gene Regulation and Mutation

43. Chapter 12
Molecular Genetics

44. Protein Folding and Stability
Chapter 12
Molecular Genetics
12.4 Gene Regulation and Mutation
Protein Folding and Stability
Substitutions also can lead to genetic disorders.
Can change both the folding and stability of the protein

45. Can occur spontaneously
Chapter 12
Molecular Genetics
12.4 Gene Regulation and Mutation
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.

46. Body-cell v. Sex-cell Mutation
Chapter 12
Molecular Genetics
12.4 Gene Regulation and Mutation
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.

47. Chapter Resource Menu Chapter Diagnostic Questions
Molecular Genetics
Chapter Resource Menu
Chapter Diagnostic Questions
Formative Test Questions
Chapter Assessment Questions
Standardized Test Practice
biologygmh.com
Glencoe Biology Transparencies
Image Bank
Vocabulary
Animation
Click on a hyperlink to view the corresponding feature.

48. Which scientist(s) definitively proved
Chapter 12
Molecular Genetics
Chapter Diagnostic Questions
Which scientist(s) definitively proved
that DNA transfers genetic material?
Watson and Crick
Mendel
Hershey and Chase
Avery A B C D
CDQ 1

49. Name the small segments of the lagging DNA strand.
Chapter 12
Molecular Genetics
Chapter Diagnostic Questions
Name the small segments of the lagging
DNA strand.
ligase
Okazaki fragments
polymerase
helicase A B C D
CDQ 2

50. Which is not true of RNA? It contains the sugar ribose.
Chapter 12
Molecular Genetics
Chapter Diagnostic Questions
Which is not true of RNA?
It contains the sugar ribose.
It contains the base uracil.
It is single-stranded.
It contains a phosphate. A B C D
CDQ 3

51. The experiments of Avery, Hershey and
Chapter 12
Molecular Genetics
12.1 Formative Questions
The experiments of Avery, Hershey and
Chase provided evidence that the carrier
of genetic information is _______.
carbohydrate
DNA
lipid
protein A B C D
FQ 1

52. What is the base-pairing rule for purines
Chapter 12
Molecular Genetics
12.1 Formative Questions
What is the base-pairing rule for purines
and pyrimidines in the DNA molecule?
A—G and C—T
A—T and C—G
C—A and G—T
C—U and A—G A B C D
FQ 2

53. What are chromosomes composed of?
Chapter 12
Molecular Genetics
12.1 Formative Questions
What are chromosomes composed of?
chromatin and histones
DNA and protein
DNA and lipids
protein and centromeres A B C D
FQ 3

54. The work of Watson and Crick solved the mystery of how DNA works as a
Chapter 12
Molecular Genetics
12.2 Formative Questions
The work of Watson and Crick solved the mystery of how DNA works as a
genetic code.
True
False A B
FQ 4

55. Which is not an enzyme involved in DNA replication?
Chapter 12
Molecular Genetics
12.2 Formative Questions
Which is not an enzyme involved in DNA
replication?
DNA ligase
DNA polymerase
hilicase
RNA primer A B C D
FQ 5

56. Which shows the basic chain of events
Chapter 12
Molecular Genetics
12.3 Formative Questions
Which shows the basic chain of events
in all organisms for reading and expressing
genes?
DNA  RNA  protein
RNA  DNA  protein
mRNA  rRNA  tRNA
RNA processing  transcription  translation A B C D
FQ 6

57. In the RNA molecule, uracil replaces _______.
Chapter 12
Molecular Genetics
12.3 Formative Questions
In the RNA molecule, uracil replaces
_______.
adenine
cytosine
purine
thymine A B C D
FQ 7

58. Which diagram shows messenger RNA (mRNA)?
Chapter 12
Molecular Genetics
12.3 Formative Questions
Which diagram shows messenger
RNA (mRNA)? A. C. B. D. A B C D
FQ 8

59. Chapter 12
Molecular Genetics
12.3 Formative Questions
What characteristic of the mRNA molecule do scientists not yet understand?
intervening sequences in the mRNA molecule called introns
the original mRNA made in the nucleus called the pre-mRNA
how the sequence of bases in the mRNA molecule codes for amino acids
the function of many adenine nucleotides at the 5′ end called the poly-A tail A B C D
FQ 9

60. Chapter 12
Molecular Genetics
12.4 Formative Questions
Why do eukaryotic cells need a complex control system to regulate the expression of genes?
All of an organism’s cells transcribe the same genes.
Expression of incorrect genes can lead to mutations.
Certain genes are expressed more frequently than others are.
Different genes are expressed at different times in an organism’s lifetime. A B C D
FQ 10

61. Which type of gene causes cells to become specialized in structure in
Chapter 12
Molecular Genetics
12.4 Formative Questions
Which type of gene causes cells to
become specialized in structure in
function?
exon
Hox gene
intron
operon A B C D
FQ 11

62. What is an immediate result of a mutation in a gene?
Chapter 12
Molecular Genetics
12.4 Formative Questions
What is an immediate result of a mutation
in a gene?
cancer
genetic disorder
nonfunctional enzyme
amino acid deficiency A B C D
FQ 12

63. Which is the most highly mutagenic?
Chapter 12
Molecular Genetics
12.4 Formative Questions
Which is the most highly mutagenic?
chemicals in food
cigarette smoke
ultraviolet radiation
X rays A B C D
FQ 13

64. chromatin fibers chromosomes histones nucleosome
Chapter 12
Molecular Genetics
Chapter Assessment Questions
Look at the following figure. Identify the proteins that DNA first coils around.
chromatin fibers
chromosomes
histones
nucleosome A B C D
CAQ 1

65. Explain how Hox genes affect an organism.
Chapter 12
Molecular Genetics
Chapter Assessment Questions
Explain how Hox genes affect an organism.
They determine size.
They determine body plan.
They determine sex.
They determine number of body segments. A B C D
CAQ 2

66. Explain the difference between body-cell and sex-cell mutation.
Chapter 12
Molecular Genetics
Chapter Assessment Questions
Explain the difference between body-cell and sex-cell mutation.
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

67. Standardized Test Practice
Chapter 12
Molecular Genetics
Standardized Test Practice
What does this diagram show about the replication of DNA in eukaryotic cells?
DNA is replicated only at certain places along the chromosome.
DNA replication is both semicontinuous and conservative.
Multiple areas of replication occur along the chromosome at the same time.
The leading DNA strand is synthesized discontinuously. A B C D
STP 1

68. What is this process called?
Chapter 12
Molecular Genetics
Standardized Test Practice
What is this process called?
mRNA processing
protein synthesis
transcription
translation A B C D
STP 2

69. TTCAGG TTCTGG What type of mutation results in this change
Chapter 12
Molecular Genetics
Standardized Test Practice
What type of mutation results in this change
in the DNA sequence?
TTCAGG TTCTGG
deletion
frameshift
insertion
substitution A B C D
STP 3

70. Standardized Test Practice
Chapter 12
Molecular Genetics
Standardized Test Practice
How could RNA interference be used to treat diseases such as cancer and diabetes?
by activating genes to produce proteins that can overcome the disease
by interfering with DNA replication in cells affected by the disease
by preventing the translation of mRNA into the genes associated with the disease
by shutting down protein synthesis in the cells of diseased tissues A B C D
STP 4

71. Chapter 12
Molecular Genetics
Standardized Test Practice
The structure of a protein can be altered dramatically by the exchange of a single
amino acid for another.
True
False A B
STP 5

72. Glencoe Biology Transparencies
Chapter 12
Molecular Genetics
Glencoe Biology Transparencies

73. Chapter 12
Molecular Genetics
Image Bank

74. Chapter 12
Molecular Genetics
Image Bank

75. Section 1 Vocabulary double helix nucleosome Chapter 12
Molecular Genetics
Vocabulary
Section 1
double helix
nucleosome

76. Section 2 Vocabulary semiconservative replication DNA polymerase
Chapter 12
Molecular Genetics
Vocabulary
Section 2
semiconservative replication
DNA polymerase
Okazaki fragment

77. Section 3 Vocabulary RNA messenger RNA ribosomal RNA transfer RNA
Chapter 12
Molecular Genetics
Vocabulary
Section 3
RNA
messenger RNA
ribosomal RNA
transfer RNA
transcription
RNA polymerase
codon
intron
exon
translation

78. Section 4 Vocabulary gene regulation operon mutation mutagen
Chapter 12
Molecular Genetics
Vocabulary
Section 4
gene regulation
operon
mutation
mutagen

79. Visualizing Transcription and Translation
Chapter 12
Molecular Genetics
Animation
Structure of DNA
DNA Polymerase
Transcription
Visualizing Transcription and Translation
Lac-Trp Operon

80. Chapter 12
Molecular Genetics

81. Chapter 12
Molecular Genetics

82. Chapter 12
Molecular Genetics

83. Chapter 12
Molecular Genetics

84. Chapter 12
Molecular Genetics