General Biology 1004 Chapter 11 Lecture Handout, Summer 2005 Dr. Frisby

Transcription

1 Slide 1 CHAPTER 11 Gene Regulation PowerPoint Lecture Slides for Essential Biology, Second Edition & Essential Biology with Physiology Presentation prepared by Chris C. Romero Neil Campbell, Jane Reece, and Eric Simon Slide 2 BIOLOGY AND SOCIETY: BABY S FIRST BANK ACCOUNT In recent years umbilical cord and placental blood has been collected at birth Figure 11.1 Slide 3 Umbilical cord and placental blood is rich in stem cells Stem cells can develop into a wide variety of different body cells

2 Slide 4 FROM EGG TO ORGANISM: HOW AND WHY GENES ARE REGULATED Four of the many different types of human cells (a) Three muscle cells (partial) (b) A nerve cell (partial) (c) Sperm cells (d) Blood cells Figure 11.2 Slide 5 In cellular differentiation Certain genes are turned on and off Cells become specialized in structure and function Slide 6 Patterns of Gene Expression in Differentiated Cells In gene expression

3 Slide 7 The regulation of gene expression plays a central role in development from a zygote to a multicellular organism Slide 8 Patterns of gene expression in specialized human cells Glycolysis enzyme genes Pancreas cell Eye lens cell (in embryo) Nerve cell Crystallin gene Insulin gene Hemoglobin gene Key: Active gene Inactive gene Figure 11.3 Slide 9 DNA Microarrays: Visualizing Gene Expression A DNA microarray allows visualization of gene expression mrna isolated cdna made from mrna cdna applied to wells Reverse transcriptase and labeled DNA nucleotides DNA microarray (each well contains DNA from a particular gene) 4 Unbound cdna rinsed away Fluorescent spot cdna Nonfluorescent spot DNA of gene DNA of gene Figure 11.4a

4 Slide 10 The pattern of glowing spots on a microarray enables researchers to determine which genes are turned on or off Figure 11.4b Slide 11 The Genetic Potential of Cells Differentiated cells Slide 12 Differentiated plant cells

5 Slide 13 Root of carrot plant Cell division in culture Plantlet Single cell Root cells in growth medium Adult plant Figure 11.5 Slide 14 The somatic cells of a single plant can be placed in a growing medium to produce clones Slide 15 Regeneration

6 Slide 16 Reproductive Cloning of Animals Nuclear transplantation Slide 17 Scottish researchers cloned the first mammal in 1997 Slide 18 The procedure that produced Dolly is called reproductive cloning Reproductive cloning Donor cell Nucleus from donor cell Implant embryo in surrogate mother Clone of donor is born Therapeutic cloning Remove nucleus from egg cell Figure 11.6 Add somatic cell from adult donor Grow in culture to produce an early embryo Remove embryonic stem cells from embryo and grow in culture Induce stem cells to form specialized cells for therapeutic use

7 Slide 19 Other organisms have since been produced using this technique, some by the pharmaceutical industry (a) Piglets (b) Banteng Figure 11.7 Slide 20 Therapeutic Cloning and Stem Cells Therapeutic cloning Slide 21 Embryonic stem cells

8 Slide 22 Liver cells Cultured embryonic stem cells Nerve cells Heart muscle cells Different culture conditions Different types of differentiated cells Figure 11.8 Slide 23 Adult stem cells Slide 24 In 2001, a biotechnology company announced that it had cloned the first human embryo Figure 11.9

9 Slide 25 THE REGULATION OF GENE EXPRESSION How is gene expression regulated in a cell? Unpacking of DNA Chromosome Gene DNA Transcription of gene Intron E xon Processing of RNA RNA transcript Flow of mrna through nuclear Cap Tail envelope mrna i n nucleus Nucleus mrna in cytoplasm Cytoplasm Translation of mrna Various changes to polypeptide Polypeptide Breakdown of mrna Active protein Breakdown of protein Broken down protein Figure Slide 26 Gene Regulation in Bacteria Bacteria can alter gene expression for metabolism based on environmental factors Slide 27 Control sequences

10 Slide 28 An operon Slide 29 A promoter An operator Slide 30 The lac operon in off mode Lactose absent Operon Regulatory gene Promoter Operator Lactose-utilization genes DNA mrna Protein Active repressor RNA polymerase cannot attach to promoter (a) Operon turned off (default state when no lactose is present) Figure 11.11a

11 Slide 31 The lac operon in on mode Lactose present DNA mrna RNA polymerase bound to promoter Protein Inactive Lactose repressor (b) Operon turned on (repressor inactivated by lactose) Enzymes for lactose utilization Figure 11.11b Slide 32 Gene Regulation in the Nucleus of Eukaryotic Cells Eukaryotic cells Slide 33 The Regulation of DNA Packing Cells may use DNA packing for long-term inactivation of genes

12 Slide 34 X chromosome inactivation Slide 35 Early embryo: Two cell populations in adult cat: Cell division and X chromosome inactivation X chromosomes Inactive X Active X Orange fur Inactive X Active X Allele for Allele for orange fur black fur Black fur Figure Slide 36 The Initiation of Transcription Eukaryotic control mechanisms

13 Slide 37 Activator proteins Other proteins Transcription factors RNA polymerase Enhancers Promoter Gene DNA Bending of DNA Transcription Figure Slide 38 Each eukaryotic gene Repressors are less common than activators Slide 39 Transcription factors Enhancers Silencers

14 Slide 40 RNA Processing The eukaryotic cell Slide 41 RNA processing includes Slide 42 Exons DNA RNA transcript RNA splicing or mrna Figure 11.14

15 Slide 43 Regulation in the Cytoplasm After eukaryotic mrna is transported to the cytoplasm, there are additional opportunities for regulation Slide 44 The Breakdown of mrna Eukaryotic mrnas Slide 45 Macromolecules (mrna, for example) Synthesis Breakdown Monomers (nucleotides, for example) Figure 11.15

16 Slide 46 The Regulation of Translation The process of translation Slide 47 Protein Alterations Post-translation control mechanisms Slide 48 Cutting Initial polypeptide Insulin (active hormone) Figure 11.16

17 Slide 49 Protein Breakdown The selective breakdown of proteins is another control mechanism operating after translation Slide 50 Cell Signaling In a multicellularorganism Slide 51 Cell-to-cell signaling

18 Slide 52 Signal transduction Signaling cell Plasma membrane Reception 1 Secretion Signal molecule 2 3 Receptor protein 4 Signal-transduction pathway Transcription factor (activated) Nucleus Target cell 5 Transcription Response mrna New protein 6 Translation Figure Slide 53 THE GENETIC BASIS OF CANCER In recent years scientists have learned more about the genetics of cancer Slide 54 Genes That Cause Cancer As early as 1911 certain viruses were known to cause cancer Cancer-causing viruses often carry specific genes called oncogenes

19 Slide 55 Oncogenes and Tumor-Suppressor Genes Proto-oncogenes Slide 56 For a proto-oncogene to become an oncogene, a mutation must occur in the cell s DNA Slide 57 Proto-oncogene DNA (a) Mutation within the gene (b) Multiple copies of the gene (c) Gene moved to new DNA locus, under new controls Oncogene New promoter Hyperactive growth-stimulating protein Normal growth-stimulating protein in excess Normal growth-stimulating protein in excess Figure 11.18

20 Slide 58 Tumor-suppressor genes Slide 59 Tumor-suppressor gene Mutated tumor-suppressor gene Normal growthinhibiting protein Defective, non-functioning protein Cell division under control Cell division not under control Figure Slide 60 The Effects of Cancer Genes on Cell-Signaling Pathways Normal proto-oncogenes and tumor-suppressor genes The proto-oncogene ras

21 Slide 61 The Progression of a Cancer Colon cancer begins as an unusually frequent division of normal-looking cells in the colon lining Colon wall Cellular changes: DNA changes: Increased cell division Oncogene activated Growth of benign tumor Tumor-suppressor gene inactivated Growth of malignant tumor Second tumor-suppressor gene inactivated (a) Stepwise development of a typical colon cancer Figure 11.20a Slide 62 Genetic changes or mutations Chromosomes 1 mutation 2 mutations 3 mutations 4 mutations Normal cell Malignant cell (b) Accumulation of mutations in the development of a cancer cel l Figure 11.20b Slide 63 Inherited Cancer Cancer is always a genetic disease because it always results from changes in DNA

22 Slide 64 In some families, mutations in one or more genes predisposing the recipient to cancer can be passed on Slide 65 Breast cancer Slide 66 The Effects of Lifestyle on Cancer Risk Cancer

23 Slide 67 Examples of carcinogens include Slide 68 Table 11.1 Slide 69 Exposure to carcinogens

24 Slide 70 EVOLUTION CONNECTION: HOMEOTIC GENES Homeotic genes Figure Slide 71 Homeoboxes Slide 72 Fly chromosome Mouse chromosomes Fruit fly embryo (10 hours) Mouse embryo (12 days) Adult fruit fly Adult mouse Figure 11.22

25 Chapter 11 Study Objectives 1. Explain how and why parents pay to collect and store the umbilical cord blood of their newborn baby. 2. Explain what makes the many types of adult human cells different. 3. Explain how DNA microarrays help us visualize gene expression. 4. Explain how every cell has the potential to act like every other cell. Illustrate with examples. 5. Explain how plants are cloned, what this reveals about cell differentiation, and why growers clone plants. 6. Explain how nuclear transplantation can be used to clone animals. Describe four advantages of reproductive cloning of animals. 7. Compare the properties of embryonic and adult stem cells. Explain the advantages and disadvantages of using adult stem cells to produce replacement tissues. 8. Explain how the lac operon works. Compare the lac operon to operons that control amino acid synthesis. 9. Explain how DNA packing influences gene expression. 10. Explain how transcription is usually initiated in eukaryotes. 11. Describe how RNA is processed in eukaryotes before it leaves the nucleus. Explain how this processing can result in different proteins from the same gene. 12. Describe four mechanisms used to regulate gene expression after eukaryotic mrna is transported to the cytoplasm. 13. Explain how cell signaling influences development.