1. Molecular Basis of Inheritance
Chapter 16
Molecular Basis of Inheritance

2. The Structure of the Genetic Material DNA Replication
Figure 10.0_1
Chapter 16: Big Ideas
The Structure of the Genetic Material
DNA Replication
Figure 10.0_1 Chapter 10: Big Ideas
The Flow of Genetic Information from DNA to RNA to Protein
The Genetics of Viruses and Bacteria 2

3. THE STRUCTURE OF THE GENETIC MATERIAL
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4. SCIENTIFIC DISCOVERY: Experiments that showed that DNA is the genetic material
In 1928, Frederick Griffith discovered that a “transforming factor” could be transferred into a bacterial cell. He found that
when he exposed heat-killed pathogenic bacteria to harmless bacteria, some harmless bacteria were converted to disease-causing bacteria and
the disease-causing characteristic was inherited by descendants of the transformed cells.
Used two strains of Strepcoccus pneumoniae Rough (R) coat = harmless and Smooth (S) coat = harmful
Student Misconceptions and Concerns
1. Understanding bacteriophage replication can be difficult for students with limited knowledge of cell biology or genetics. Therefore, understanding the methods, results, and significance of the Hershey and Chase experiments is even more problematic. Considerable time and attention to these details will be required for many of your students.
2. If your class has not yet studied Chapter 3, consider assigning module 3.15 on “Nucleic Acids” before addressing the contents of Chapter 10.
Teaching Tips
1. A phage functions like a needle and syringe, injecting a drug. The needle and syringe are analogous to the protein components of the phage. The drug to be injected is analogous to the phage DNA.
2. The descriptions of the discovery of DNA’s structure are a good time to point out that science is a collaborative effort. Watson, Crick, and Wilkins earned Nobel prizes due to their historic conclusions based upon the work of many others (including Franklin, Griffith, Hershey, Chase, and Chargaff).
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5. SCIENTIFIC DISCOVERY: Experiments that showed that DNA is the genetic material
Conclusion: The rough strain was transformed to smooth strain in the mouse body. How??

6. SCIENTIFIC DISCOVERY: Experiments that showed that DNA is the genetic material
Avery, McCarty and MacLeod
Separated and purified the S cell contents
Mixed with live R cells and injected into mice
Only the mice with DNA extract died

7. SCIENTIFIC DISCOVERY: Experiments that showed that DNA is the genetic material
Until the 1940s, the case for proteins serving as the genetic material was stronger than the case for DNA.
Proteins are made from 20 different amino acids.
DNA was known to be made from just four kinds of nucleotides.
Scientists were still skeptical about these results
Student Misconceptions and Concerns
1. Understanding bacteriophage replication can be difficult for students with limited knowledge of cell biology or genetics. Therefore, understanding the methods, results, and significance of the Hershey and Chase experiments is even more problematic. Considerable time and attention to these details will be required for many of your students.
2. If your class has not yet studied Chapter 3, consider assigning module 3.15 on “Nucleic Acids” before addressing the contents of Chapter 10.
Teaching Tips
1. A phage functions like a needle and syringe, injecting a drug. The needle and syringe are analogous to the protein components of the phage. The drug to be injected is analogous to the phage DNA.
2. The descriptions of the discovery of DNA’s structure are a good time to point out that science is a collaborative effort. Watson, Crick, and Wilkins earned Nobel prizes due to their historic conclusions based upon the work of many others (including Franklin, Griffith, Hershey, Chase, and Chargaff).
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8. SCIENTIFIC DISCOVERY: Experiments showed that DNA is the genetic material
In 1952, Alfred Hershey and Martha Chase used bacteriophages to show that DNA is the genetic material of T2, a virus that infects the bacterium Escherichia coli (E. coli).
Bacteriophages (or phages for short) are viruses that infect bacterial cells.
Phages were labeled with radioactive sulfur to detect proteins or radioactive phosphorus to detect DNA.
Bacteria were infected with either type of labeled phage to determine which substance was injected into cells and which remained outside the infected cell.
Student Misconceptions and Concerns
1. Understanding bacteriophage replication can be difficult for students with limited knowledge of cell biology or genetics. Therefore, understanding the methods, results, and significance of the Hershey and Chase experiments is even more problematic. Considerable time and attention to these details will be required for many of your students.
2. If your class has not yet studied Chapter 3, consider assigning module 3.15 on “Nucleic Acids” before addressing the contents of Chapter 10.
Teaching Tips
1. A phage functions like a needle and syringe, injecting a drug. The needle and syringe are analogous to the protein components of the phage. The drug to be injected is analogous to the phage DNA.
2. The descriptions of the discovery of DNA’s structure are a good time to point out that science is a collaborative effort. Watson, Crick, and Wilkins earned Nobel prizes due to their historic conclusions based upon the work of many others (including Franklin, Griffith, Hershey, Chase, and Chargaff).
© 2012 Pearson Education, Inc. 8

9. Life cycle of the bacteriophage
Figure 10.1A
Life cycle of the bacteriophage
Head
DNA
Tail
Tail fiber
Figure 10.1A Phage T2 9

10. A phage attaches itself to a bacterial cell.
Figure 10.1C 1
A phage attaches itself to a bacterial cell. 2
The phage injects its DNA into the bacterium. 3
The phage DNA directs the host cell to make more phage DNA and proteins; new phages assemble. 4
The cell lyses and releases the new phages.
Figure 10.1C A phage replication cycle 10

11. 10.1 SCIENTIFIC DISCOVERY: Experiments showed that DNA is the genetic material
The sulfur-labeled protein stayed with the phages outside the bacterial cell, while the phosphorus-labeled DNA was detected inside cells.
Cells with phosphorus-labeled DNA produced new bacteriophages with radioactivity in DNA but not in protein.
Student Misconceptions and Concerns
1. Understanding bacteriophage replication can be difficult for students with limited knowledge of cell biology or genetics. Therefore, understanding the methods, results, and significance of the Hershey and Chase experiments is even more problematic. Considerable time and attention to these details will be required for many of your students.
2. If your class has not yet studied Chapter 3, consider assigning module 3.15 on “Nucleic Acids” before addressing the contents of Chapter 10.
Teaching Tips
1. A phage functions like a needle and syringe, injecting a drug. The needle and syringe are analogous to the protein components of the phage. The drug to be injected is analogous to the phage DNA.
2. The descriptions of the discovery of DNA’s structure are a good time to point out that science is a collaborative effort. Watson, Crick, and Wilkins earned Nobel prizes due to their historic conclusions based upon the work of many others (including Franklin, Griffith, Hershey, Chase, and Chargaff).
Animation: Hershey-Chase Experiment
Animation: Phage T2 Reproductive Cycle
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12. Batch 1: Radioactive protein labeled in yellow
Figure 10.1B_1
Empty protein shell
Radioactive protein
Phage
Bacterium
Phage DNA
DNA
Batch 1: Radioactive protein labeled in yellow 1 2
Figure 10.1B_1 The Hershey-Chase experiment (part 1)
Batch 2: Radioactive DNA labeled in green
Radioactive DNA 12

13. The radioactivity is in the liquid.
Figure 10.1B_2
Empty protein shell
The radioactivity is in the liquid.
Phage DNA
Centrifuge
Pellet 3 4
Figure 10.1B_2 The Hershey-Chase experiment (part 2)
Centrifuge
The radioactivity is in the pellet.
Pellet 13

14. The radioactivity is in the liquid.
Figure 10.1B
Radioactive protein
Empty protein shell
Phage
The radioactivity is in the liquid.
Bacterium
Phage DNA
Batch 1: Radioactive protein labeled in yellow
DNA
Centrifuge
Pellet 1 2 3 4
Figure 10.1B The Hershey-Chase experiment
Batch 2: Radioactive DNA labeled in green
Radioactive DNA
Centrifuge
The radioactivity is in the pellet.
Pellet 14

15. Figure 10.0_2
Figure 10.0_2 Herpesvirus 15

16. DNA is the genetic material
What does DNA look like and how does it work as genetics material?
DNA and RNA are nucleic acids.
One of the two strands of DNA is a DNA polynucleotide, a nucleotide polymer (chain).
A nucleotide is composed of a
nitrogenous base,
five-carbon sugar, and
phosphate group.
Student Misconceptions and Concerns
1. If your class has not yet studied Chapter 3, consider assigning module 3.15 on “Nucleic Acids” before addressing the contents of Chapter 10.
2. Students often confuse the terms nucleic acids, nucleotides, and bases. It helps to note the hierarchy of relationships: nucleic acids consist of long chains of nucleotides (polynucleotides), while nucleotides include nitrogenous bases.
Teaching Tips
1. The descriptions of the discovery of DNA’s structure are a good time to point out that science is a collaborative effort. Watson, Crick, and Wilkins earned Nobel prizes due to their historic conclusions based upon the work of many others (including Franklin, Griffith, Hershey, Chase, and Chargaff).
2. Consider comparing DNA, RNA, and proteins to a train (polymer). DNA and RNA are like a train of various lengths and combinations of four types of train cars (monomers). Proteins are also “trains” of various lengths but made of a combination of 20 types of train cars.
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17. Thymine (T) Phosphate group
Figure 10.2A_3
Nitrogenous base (can be A, G, C, or T)
Thymine (T)
Phosphate group
Figure 10.2A_3 The structure of a DNA polynucleotide (part 3)
Sugar (deoxyribose)
DNA nucleotide 17

18. Thymine (T) Cytosine (C) Adenine (A) Guanine (G) Pyrimidines Purines
Figure 10.2B
Thymine (T)
Cytosine (C)
Adenine (A)
Guanine (G)
Pyrimidines
Purines
Figure 10.2B The nitrogenous bases of DNA 18

19. DNA are polymers of nucleotides Animation: DNA and RNA Structure
Each type of DNA nucleotide has a different nitrogen-containing base:
adenine (A),
cytosine (C),
thymine (T), and
guanine (G).
Chargaff isolated and quantified the amount of A, T, G, C from cells and found
Quantity of A=T
Quantity of G=C
Known as Chargaff’s rules
Student Misconceptions and Concerns
1. If your class has not yet studied Chapter 3, consider assigning module 3.15 on “Nucleic Acids” before addressing the contents of Chapter 10.
2. Students often confuse the terms nucleic acids, nucleotides, and bases. It helps to note the hierarchy of relationships: nucleic acids consist of long chains of nucleotides (polynucleotides), while nucleotides include nitrogenous bases.
Teaching Tips
1. The descriptions of the discovery of DNA’s structure are a good time to point out that science is a collaborative effort. Watson, Crick, and Wilkins earned Nobel prizes due to their historic conclusions based upon the work of many others (including Franklin, Griffith, Hershey, Chase, and Chargaff).
2. Consider comparing DNA, RNA, and proteins to a train (polymer). DNA and RNA are like a train of various lengths and combinations of four types of train cars (monomers). Proteins are also “trains” of various lengths but made of a combination of 20 types of train cars.
Animation: DNA and RNA Structure
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20. DNA are polymers of nucleotides
More evidence for DNA as the genetic material
DNA doubles in cells getting ready for cell division
A haploid cell has half as much DNA as a diploid cell
Race to discover the DNA structure was on!
Contenders:
Wilkins and Franklin of England
Linus Pauling of USA
Watson and Crick of ……

21. Discovery of DNA Structure
World renowned X- ray crystallography expert
X-rays of DNA
Information can be used to find out the width of molecule
Spacing between bases
Figure 10.3A Rosalind Franklin and her X-ray image of DNA 21

22. 10.3 SCIENTIFIC DISCOVERY: DNA is a double-stranded helix
In 1953, James D. Watson and Francis Crick deduced the secondary structure of DNA, using
X-ray crystallography data of DNA from the work of Rosalind Franklin and Maurice Wilkins and
Chargaff’s observation that in DNA,
the amount of adenine was equal to the amount of thymine and
the amount of guanine was equal to that of cytosine.
Student Misconceptions and Concerns
Students often confuse the terms nucleic acids, nucleotides, and bases. It helps to note the hierarchy of relationships: nucleic acids consist of long chains of nucleotides (polynucleotides), while nucleotides include nitrogenous bases.
Teaching Tips
1. The descriptions of the discovery of DNA’s structure are a good time to point out that science is a collaborative effort. Watson, Crick, and Wilkins earned Nobel prizes due to their historic conclusions based upon the work of many others (including Franklin, Griffith, Hershey, Chase, and Chargaff).
2. The authors note that the structure of DNA is analogous to a twisted rope ladder. In class, challenge your students to explain what the parts of the ladder represent. The wooden rungs represent pairs of nitrogenous bases joined by hydrogen bonds. Each rope represents a sugar-phosphate backbone.
© 2012 Pearson Education, Inc. 22

23. 10.3 SCIENTIFIC DISCOVERY: DNA is a double-stranded helix
Watson and Crick reported that DNA consisted of two polynucleotide strands wrapped into a double helix.
The sugar-phosphate backbone is on the outside.
The nitrogenous bases are perpendicular to the backbone in the interior.
Specific pairs of bases give the helix a uniform shape.
A pairs with T, forming two hydrogen bonds, and
G pairs with C, forming three hydrogen bonds.
The two strands are anti-parallel
Student Misconceptions and Concerns
Students often confuse the terms nucleic acids, nucleotides, and bases. It helps to note the hierarchy of relationships: nucleic acids consist of long chains of nucleotides (polynucleotides), while nucleotides include nitrogenous bases.
Teaching Tips
1. The descriptions of the discovery of DNA’s structure are a good time to point out that science is a collaborative effort. Watson, Crick, and Wilkins earned Nobel prizes due to their historic conclusions based upon the work of many others (including Franklin, Griffith, Hershey, Chase, and Chargaff).
2. The authors note that the structure of DNA is analogous to a twisted rope ladder. In class, challenge your students to explain what the parts of the ladder represent. The wooden rungs represent pairs of nitrogenous bases joined by hydrogen bonds. Each rope represents a sugar-phosphate backbone.
© 2012 Pearson Education, Inc. 23

24. Figure 10.3B
Figure 10.3B Watson and Crick in 1953 with their model of the DNA double helix 24

25. Watson and ….. Circa 2004

26. Sugar-phosphate backbone
Figure 10.2A A T C G T A
Sugar-phosphate backbone C G
Phosphate group A T G C A G A
Nitrogenous base
Nitrogenous base (can be A, G, C, or T)
Covalent bond joining nucleotides A T G C
Sugar T A T A C C C C C G T A
DNA nucleotide
Thymine (T)
A DNA double helix T T T
Phosphate group
Figure 10.2A The structure of a DNA polynucleotide G G
Sugar (deoxyribose)
DNA nucleotide G G
Two representations of a DNA polynucleotide 26

27. Sugar-phosphate backbone
Figure 10.2A_2
Sugar-phosphate backbone
Phosphate group A A
Nitrogenous base
Covalent bond joining nucleotides
Sugar C C
DNA nucleotide T T G G
Figure 10.2A_2 The structure of a DNA polynucleotide (part 2) G G
Two representations of a DNA polynucleotide 27

28. Partial chemical structure
Figure 10.3D_2
Hydrogen bond
G C
T A
A T
Figure 10.3D_2 Three representations of DNA (part 2)
C G
Partial chemical structure 28

29. Figure 10.3C
Figure 10.3C A rope ladder model for the double helix
Twist 29

30. 10.3 SCIENTIFIC DISCOVERY: DNA is a double-stranded helix
In 1962, the Nobel Prize was awarded to
James D. Watson, Francis Crick, and Maurice Wilkins.
Rosalind Franklin probably would have received the prize as well but for her death from cancer in Nobel Prizes are never awarded posthumously.
The Watson-Crick model gave new meaning to the words genes and chromosomes. The genetic information in a chromosome is encoded in the nucleotide sequence of DNA.
Student Misconceptions and Concerns
Students often confuse the terms nucleic acids, nucleotides, and bases. It helps to note the hierarchy of relationships: nucleic acids consist of long chains of nucleotides (polynucleotides), while nucleotides include nitrogenous bases.
Teaching Tips
1. The descriptions of the discovery of DNA’s structure are a good time to point out that science is a collaborative effort. Watson, Crick, and Wilkins earned Nobel prizes due to their historic conclusions based upon the work of many others (including Franklin, Griffith, Hershey, Chase, and Chargaff).
2. The authors note that the structure of DNA is analogous to a twisted rope ladder. In class, challenge your students to explain what the parts of the ladder represent. The wooden rungs represent pairs of nitrogenous bases joined by hydrogen bonds. Each rope represents a sugar-phosphate backbone.
© 2012 Pearson Education, Inc. 30

31. DNA REPLICATION
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32. 10.4 DNA replication depends on specific base pairing
In their description of the structure of DNA, Watson and Crick noted that the structure of DNA suggests a possible copying mechanism.
DNA replication follows a semiconservative model.
The two DNA strands separate.
Each strand is used as a pattern to produce a complementary strand, using specific base pairing.
Each new DNA helix has one old strand with one new strand.
Student Misconceptions and Concerns
The authors note that although the general process of semiconservative DNA replication is relatively simple, it involves complex biochemical gymnastics. The DNA molecule is unwound, each strand is copied simultaneously, the correct bases are inserted, and the product is proofread and corrected. Before discussing these details, be sure that your students understand the overall process, what is accomplished, and why each step is important.
Teaching Tips
1. Demonstrate the complementary base pairing within DNA. Present students with the base sequence to one side of a DNA molecule and have them work quickly at their seats to determine the sequence of the complimentary strand. For some students, these sorts of quick practice are necessary to reinforce a concept and break up a lecture.
2. The semiconservative model of DNA replication is like making a photo from a negative and then a new negative from the photo. In each new negative and photo pair, the new item was made from an old item.
Animation: DNA Replication Overview
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33. How does the DNA make a copy of itself - Replication
Conservative: The parent DNA strands remain together after replication and the daughter DNA consists of new strands
Semi-conservative: Each new DNA consists of a parent and a new strand
Dispersive: Each daughter DNA consists of a mixture of parent and daughter DNA

34. Meselson and Stahl Experiment with Light and Heavy Nitrogen
Grew E. coli in heavy nitrogen N15 till all DNA showed as a heavy band when centrifuged
Transferred to N14 and grew for one generation
Prediction for each type of replication?
Grew for second generation in N14
Prediction?
Grew for the third generation in N14

35. Meselson and Stahl Experiment with Light and Heavy Nitrogen

36. A parental molecule of DNA
Figure 10.4A_s1
A T
C G
G C
A T
T A
A parental molecule of DNA
Figure 10.4A_s1 A template model for DNA replication (step 1) 36

37. A parental molecule of DNA
Figure 10.4A_s2
A T T A A T
C G C G G C
G C G C C A
A T A T
Free nucleotides
T A T A
A parental molecule of DNA
The parental strands separate and serve as templates
Figure 10.4A_s2 A template model for DNA replication (step 2) 37

38. A parental molecule of DNA
Figure 10.4A_s3
A T T A A T
A T
A T
C G C G G
C G
C G C
G C G C C
G C
G C A
A T A T
A T
A T
Free nucleotides
T A T A
T A
T A
A parental molecule of DNA
The parental strands separate and serve as templates
Two identical daughter molecules of DNA are formed
Figure 10.4A-s3 A template model for DNA replication (step 3) 38

39. Daughter DNA molecules
Figure 10.4B
A T
G C
A T
Parental DNA molecule
A T
T A C G C G T
Daughter strand A
C G
C G
C G
Parental strand T
C G A
Figure 10.4B The untwisting and replication of DNA
C G
A T
T A
A T
C G
G C
A T T
A T A
A T
G C
Daughter DNA molecules 39

40. 10.5 DNA replication proceeds in two directions at many sites simultaneously
DNA replication begins at the origins of replication where
DNA unwinds at the origin to produce a “bubble,”
replication proceeds in both directions from the origin, and
replication ends when products from the bubbles merge with each other.
Student Misconceptions and Concerns
The authors note that although the general process of semiconservative DNA replication is relatively simple, it involves complex biochemical gymnastics. The DNA molecule is unwound, each strand is copied simultaneously, the correct bases are inserted, and the product is proofread and corrected. Before discussing these details, be sure that your students understand the overall process, what is accomplished, and why each step is important.
Teaching Tips
1. To explain the adaptive advantage of multiple replication sites over a single site of replication, ask the students to imagine copying, by hand, the first ten chapters of your biology textbook. The task would certainly go faster if ten students each copied a different chapter.
2. There are about 500,000 words in the Biology: Concepts & Connections textbook. The accuracy of DNA replication would be like copying every word in this textbook by hand 2,000 times and writing just one word incorrectly, making one error in every 1 billion words.
© 2012 Pearson Education, Inc. 40

41. Two daughter DNA molecules
Figure 10.5A
Parental DNA molecule
Origin of replication
Parental strand
Daughter strand
“Bubble”
Figure 10.5A Multiple bubbles in replicating DNA
Two daughter DNA molecules 41

42. 10.5 DNA replication proceeds in two directions at many sites simultaneously
DNA replication occurs in the 5 to 3 direction.
Replication is continuous on the 3 to 5 template.
Replication is discontinuous on the 5 to 3 template, forming short segments.
Student Misconceptions and Concerns
The authors note that although the general process of semiconservative DNA replication is relatively simple, it involves complex biochemical gymnastics. The DNA molecule is unwound, each strand is copied simultaneously, the correct bases are inserted, and the product is proofread and corrected. Before discussing these details, be sure that your students understand the overall process, what is accomplished, and why each step is important.
Teaching Tips
1. To explain the adaptive advantage of multiple replication sites over a single site of replication, ask the students to imagine copying, by hand, the first ten chapters of your biology textbook. The task would certainly go faster if ten students each copied a different chapter.
2. There are about 500,000 words in the Biology: Concepts & Connections textbook. The accuracy of DNA replication would be like copying every word in this textbook by hand 2,000 times and writing just one word incorrectly, making one error in every 1 billion words.
© 2012 Pearson Education, Inc. 42

43. 5 end 3 end P HO A T P P C G P P G C P P T A OH P 3 end 5 end 5
Figure 10.5B
5 end
3 end P HO 5 2 4 A T 3 3 1 1 2 4 P 5 P C G P P G C
Figure 10.5B The opposite orientations of DNA strands P P T A OH P
3 end
5 end 43

44. 10.5 DNA replication proceeds in two directions at many sites simultaneously
Proteins are involved in DNA replication.
DNA ligase joins small fragments into a continuous chain.
DNA polymerase I and III
adds nucleotides to a growing chain and
proofreads and corrects improper base pairings.
Helicase – unwinds DNA at replication fork
Single stranded binding protein – stabilizes unwound DNA
Topoisomerase – corrects overwinding ahead of DNA fork by breaking and joining DNA
Student Misconceptions and Concerns
The authors note that although the general process of semiconservative DNA replication is relatively simple, it involves complex biochemical gymnastics. The DNA molecule is unwound, each strand is copied simultaneously, the correct bases are inserted, and the product is proofread and corrected. Before discussing these details, be sure that your students understand the overall process, what is accomplished, and why each step is important.
Teaching Tips
1. To explain the adaptive advantage of multiple replication sites over a single site of replication, ask the students to imagine copying, by hand, the first ten chapters of your biology textbook. The task would certainly go faster if ten students each copied a different chapter.
2. There are about 500,000 words in the Biology: Concepts & Connections textbook. The accuracy of DNA replication would be like copying every word in this textbook by hand 2,000 times and writing just one word incorrectly, making one error in every 1 billion words.
© 2012 Pearson Education, Inc. 44

45. 10.5 DNA replication proceeds in two directions at many sites simultaneously
DNA polymerases and DNA ligase also repair DNA damaged by harmful radiation and toxic chemicals.
DNA replication ensures that all the somatic cells in a multicellular organism carry the same genetic information.
Student Misconceptions and Concerns
The authors note that although the general process of semiconservative DNA replication is relatively simple, it involves complex biochemical gymnastics. The DNA molecule is unwound, each strand is copied simultaneously, the correct bases are inserted, and the product is proofread and corrected. Before discussing these details, be sure that your students understand the overall process, what is accomplished, and why each step is important.
Teaching Tips
1. To explain the adaptive advantage of multiple replication sites over a single site of replication, ask the students to imagine copying, by hand, the first ten chapters of your biology textbook. The task would certainly go faster if ten students each copied a different chapter.
2. There are about 500,000 words in the Biology: Concepts & Connections textbook. The accuracy of DNA replication would be like copying every word in this textbook by hand 2,000 times and writing just one word incorrectly, making one error in every 1 billion words.
© 2012 Pearson Education, Inc. 45

46. DNA Replication Process
Helicase unwinds the DNA double helix
Single stranded binding proteins stabilize the unwound DNA

47. DNA Replication
Primase synthesizes a small section of RNA on each 5’ end
Nucleotides pair up
DNA Pol III joins the backbone together

48. DNA Replication

49. DNA polymerase molecule
Figure 10.5C 3
DNA polymerase molecule
This daughter strand is synthesized continuously 5
Parental DNA 5 3
Replication fork
This daughter strand is synthesized in pieces 3 5
Figure 10.5C How daughter DNA strands are synthesized 5 3
DNA ligase
Overall direction of replication 49

50. DNA Replication
DNA Pol I removes the primer and replaces with DNA nucleotides
A gap formed is sealed with DNA Ligase

51. Molecular process of DNA replication

52. You should now be able to
Describe the experiments of Griffith, Hershey, and Chase, which supported the idea that DNA was life’s genetic material.
Explain the structure of DNA.
Explain how the structure of DNA facilitates its replication.
Describe the process of DNA replication.
© 2012 Pearson Education, Inc. 52