2. Table of Contents Section 1 Control of Gene Expression
Chapter 11
Gene Expression
Table of Contents
Section 1 Control of Gene Expression
Section 2 Gene Expression in Development and Cell Division

3. Objectives Chapter 11 Section 1 Control of Gene Expression
Explain why cells regulate gene expression.
Discuss the role of operons in prokaryotic gene expression.
Determine how repressor proteins and inducers affect transcription in prokaryotes.
Describe the structure of a eukaryotic gene.
Compare the two ways gene expression is controlled in eukaryotes.

4. Role of Gene Expression
Section 1 Control of Gene Expression
Chapter 11
Role of Gene Expression
Gene expression is the activation of a gene that results in transcription and the production of mRNA.
Only a fraction of any cell’s genes are expressed at any one time.

5. Gene Expression in Prokaryotes
Section 1 Control of Gene Expression
Chapter 11
Gene Expression in Prokaryotes
An operon is a series of genes that code for specific products and the regulatory elements that control these genes. In prokaryotes, the structural genes, the promoter, and the operator collectively form an operon.

6. Chapter 11 Operon Section 1 Control of Gene Expression
Click below to watch the Visual Concept.
Visual Concept

7. Gene Expression in Prokaryotes, continued
Section 1 Control of Gene Expression
Chapter 11
Gene Expression in Prokaryotes, continued
A promoter is the segment of DNA that is recognized by the enzyme RNA polymerase, which then initiates transcription.
An operator is the segment of DNA that acts as a “switch” by controlling the access of RNA polymerase to the promoter.

8. Gene Expression in Prokaryotes, continued
Section 1 Control of Gene Expression
Chapter 11
Gene Expression in Prokaryotes, continued
Operon “Turned Off”
Repressor proteins are coded for by regulator genes and these proteins inhibit genes from being expressed.
A repressor protein attaches to the operator, physically blocking the advancement of RNA polymerase.

9. Repression of Transcription in the lac Operon
Section 1 Control of Gene Expression
Chapter 11
Repression of Transcription in the lac Operon
Click below to watch the Visual Concept.
Visual Concept

10. Gene Expression in Prokaryotes, continued
Section 1 Control of Gene Expression
Chapter 11
Gene Expression in Prokaryotes, continued
Operon “Turned On”
An inducer is a molecule that initiates gene expression. In E. coli, lactose serves as an inducer.
An inducer binds to the repressor protein and the repressor protein detaches from the operator. RNA polymerase can then advance to the structural genes.

11. Activation of Transcription in the lac Operon
Section 1 Control of Gene Expression
Chapter 11
Activation of Transcription in the lac Operon
Click below to watch the Visual Concept.
Visual Concept

12. Mechanism of lac Operon
Section 1 Control of Gene Expression
Chapter 11
Mechanism of lac Operon

17. How are these skin cells different? Do they have the same DNA?

18. Gene Expression in Eukaryotes
Structure of a Eukaryotic Gene
Eukaryotes do not have operons.
The genomes of eukaryotes are larger and more complex than those of prokaryotes.
Eukaryotic genes are organized into noncoding sections, called introns, and coding sections, called exons.

19. Control After Transcription
In eukaryotes, gene expression can be controlled after transcription—through the removal of introns from pre-mRNA.

21. Control at the Onset of Transcription In eukaryotes, gene expression can be controlled at the onset of transcription—through the action of regulatory proteins known as transcription factors.

22. CANCER- (Malignant Neoplasms)
ANIMATED INTRODUCTION TO CANCER BIOLOGY (FULL DOCUMENTARY) 12:07

23. Section 2 Gene Expression in Development and Cell Division
Chapter 11
Objectives
Summarize the role of gene expression in an organism’s development.
Describe the influence of homeotic genes in eukaryotic development.
State the role of the homeobox in eukaryotic development.
Summarize the effects of mutations in causing cancer.
Compare the characteristics of cancer cells with those of normal cells.

24. Gene Expression in Development
Section 2 Gene Expression in Development and Cell Division
Chapter 11
Gene Expression in Development
The development of cells with specialized functions is called cell differentiation.
The development of form in an organism is called morphogenesis.
Both cell differentiation and morphogenesis are governed by gene expression.

25. The development of cells with specialized functions is called cell differentiation.
The development of form in an organism is called morphogenesis.
Both cell differentiation and morphogenesis are governed by gene expression.

26. Homeotic Genes
Homeotic genes are regulatory genes that determine where anatomical structures will be placed during development.

27. Homeobox Sequences
Within each homeotic gene, a specific DNA sequence known as the homeobox regulates patterns of development.
The homeoboxes of many eukaryotic organisms appear to be very similar.

28. Tracking Changes in Gene Expression
In the 1990s, researchers developed a tool for tracking gene expression called a DNA chip.

29. Gene Expression, Cell Division, and Cancer
Mutations of proto-oncogenes, which regulate cell growth, or tumor-suppressor genes, which prevent cell division from occurring too often, may lead to cancer.
Cancer is the uncontrolled growth of abnormal cells.

30. Types of Cancer
Carcinomas- Skin and tissues that line the organs
Sarcomas- bone and muscle tissue
Lymphomas- lymphatic system
Leukemia- blood

33. Effect of Mutation on Gene Expression

34. Gene Expression in Cancer
Unlike normal cells, cancer cells continue to divide indefinitely, even if they become densely packed.
Cancer cells will also continue dividing even if they are no longer attached to other cells.

35. Causes of Cancer
A carcinogen is any substance that can induce or promote cancer.
Most carcinogens are mutagens, substances that cause mutations.

36. Chapter 11
Standardized Test Prep
Multiple Choice
1. Which of the following codes for a repressor protein?
A. enhancer
B. promoter
C. regulator gene
D. structural gene

37. Multiple Choice, continued
Chapter 11
Standardized Test Prep
Multiple Choice, continued
1. Which of the following codes for a repressor protein?
A. enhancer
B. promoter
C. regulator gene
D. structural gene

38. Multiple Choice, continued
Chapter 11
Standardized Test Prep
Multiple Choice, continued
2. Which component of an operon controls the advancement of RNA polymerase?
F. exon
G. operator
H. promoter
J. structural gene

39. Multiple Choice, continued
Chapter 11
Standardized Test Prep
Multiple Choice, continued
2. Which component of an operon controls the advancement of RNA polymerase?
F. exon
G. operator
H. promoter
J. structural gene

40. Multiple Choice, continued
Chapter 11
Standardized Test Prep
Multiple Choice, continued
3. Pre-mRNA contains which of the following?
A. exons only
B. introns only
C. both introns and exons
D. neither introns nor exons

41. Multiple Choice, continued
Chapter 11
Standardized Test Prep
Multiple Choice, continued
3. Pre-mRNA contains which of the following?
A. exons only
B. introns only
C. both introns and exons
D. neither introns nor exons

42. Multiple Choice, continued
Chapter 11
Standardized Test Prep
Multiple Choice, continued
The graph below shows the number of cigarettes smoked per capita per year between 1920 and 2000 and the annual incidence of lung cancer among women. Use the graph to answer the question that follows.
4. What was the relationship between number of cigarettes smoked and incidence of lung cancer?
F. There was no relationship between cigarette smoking and lung cancer.
G. As the number of cigarettes smoked decreased, the incidence of lung cancer increased.
H. As the number of cigarettes smoked increased, the incidence of lung cancer increased.
J. As the number of cigarettes smoked increased, the incidence of lung cancer decreased.

43. Multiple Choice, continued
Chapter 11
Standardized Test Prep
Multiple Choice, continued
The graph below shows the number of cigarettes smoked per capita per year between 1920 and 2000 and the annual incidence of lung cancer among women. Use the graph to answer the question that follows.
4. What was the relationship between number of cigarettes smoked and incidence of lung cancer?
F. There was no relationship between cigarette smoking and lung cancer.
G. As the number of cigarettes smoked decreased, the incidence of lung cancer increased.
H. As the number of cigarettes smoked increased, the incidence of lung cancer increased.
J. As the number of cigarettes smoked increased, the incidence of lung cancer decreased.

44. Multiple Choice, continued
Chapter 11
Standardized Test Prep
Multiple Choice, continued
5. skin : carcinoma :: blood-forming tissue :
A. sarcoma
B. leukemia
C. lymphoma
D. carcinogen

45. Multiple Choice, continued
Chapter 11
Standardized Test Prep
Multiple Choice, continued
5. skin : carcinoma :: blood-forming tissue :
A. sarcoma
B. leukemia
C. lymphoma
D. carcinogen

46. Multiple Choice, continued
Chapter 11
Standardized Test Prep
Multiple Choice, continued
The diagram below shows how mutations in certain genes can lead to cancer. Use the diagram to answer the questions that follow.
6. What does X represent?
F. mutagens
G. carcinogens
H. proto-oncogenes
J. tumor-suppressor genes

47. Multiple Choice, continued
Chapter 11
Standardized Test Prep
Multiple Choice, continued
The diagram below shows how mutations in certain genes can lead to cancer. Use the diagram to answer the questions that follow.
6. What does X represent?
F. mutagens
G. carcinogens
H. proto-oncogenes
J. tumor-suppressor genes

48. Multiple Choice, continued
Chapter 11
Standardized Test Prep
Multiple Choice, continued
The diagram below shows how mutations in certain genes can lead to cancer. Use the diagram to answer the questions that follow.
7. What does Y represent?
A. mutagens
B. carcinogens
C. proto-oncogenes
D. tumor-suppressor genes

49. Multiple Choice, continued
Chapter 11
Standardized Test Prep
Multiple Choice, continued
The diagram below shows how mutations in certain genes can lead to cancer. Use the diagram to answer the questions that follow.
7. What does Y represent?
A. mutagens
B. carcinogens
C. proto-oncogenes
D. tumor-suppressor genes