1. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh Edition Solomon Berg Martin Chapter 16 Genes and Development

2. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 16 Genes and Development Development of an organism –Organisms contain many types of cells specialized both structurally and metabolically –All descend from a single zygote –Development is all changes that occur in life Cell determination –Groups of cells become committed –Leads to cell differentiation –Differences among cell types due to differential gene expression

3. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 16 Genes and Development Nuclear equivalence Nuclei of all differentiated cells are genetically identical Different cells express different subsets of genes –Somatic cells –Germ line cells Totipotency –Capability of cells to direct development of entire organism

4. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 16 Genes and Development Vertebrate cell lineages

5. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 16 Genes and Development Cell totipotency

6. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 16 Genes and Development Nuclear totipotency

7. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 16 Genes and Development Mouse models to study disease Ethically researchers often cannot use humans as test subjects Animal model is used instead –An example is cystic fibrosis, a genetic disease –Gene targeting is used to produce mice homozygous or heterozygous for cystic fibrosis

8. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 16 Genes and Development First cloned mammal 1997 Cloned sheep “Dolly” was born in Scotland Genetic material derived from –Cultured adult sheep’s mammary gland cell –Fused with enucleated sheep’s egg –Cultured in vitro and transferred to host mother

9. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 16 Genes and Development Mammalian cloning

10. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 16 Genes and Development Stem cells Undifferentiated cells Can produce differentiated descendants Also retain ability to reproduce themselves Totipotent stem cells –Give rise to all cell types Pluripotent stem cells –More specialized

11. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 16 Genes and Development Exceptions to nuclear equivalence Genomic rearrangements –Physical changes in gene structure Gene amplification –More copies of certain genes for transcription

12. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 16 Genes and Development Gene amplification

13. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 16 Genes and Development Choice of organisms for research in developmental genetics Fruit fly, Drosophila melanogaster –Abundance of mutant alleles and ease of mapping new mutations on the chromosomes Roundworm, Caenorhabditis elegans –Lineage of every somatic cell is known Laboratory mouse, Mus musculus –Used in studies of mammalian development

14. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 16 Genes and Development Life cycle of Drosophila

15. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 16 Genes and Development Location of imaginal discs in Drosophila

16. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 16 Genes and Development Maternal effect genes Genes that organize structure of egg cells Genes in maternal tissues transcribed to produce mRNA molecules that are transported in egg Analysis of mutant Drosophila revealed that these genes involved in polarity of embryo

17. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 16 Genes and Development Early development in Drosophila

18. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 16 Genes and Development Classes of genes involved in pattern formation of embryonic segments in Drosophila

19. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 16 Genes and Development Segmentation genes Genes that generate a repeating pattern of body segments within embryo –Gap genes –Pair-rule genes –Segment polarity genes –Homeotic genes

20. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 16 Genes and Development Comparison of mutations in Drosophila segmented genes

21. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 16 Genes and Development Antennapedia Locus

22. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 16 Genes and Development Hox gene clusters

23. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 16 Genes and Development Induction and apoptosis Induction in C. elegans –Developmental interactions with neighboring cells –Anchor cell induces surface cells to form vulva Apoptosis in humans –During development, hand forms a webbed structure –Fingers become individualized when cells between them die

24. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 16 Genes and Development Caenorhabditis elegans

25. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 16 Genes and Development Cell lineages of C. elegans

26. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 16 Genes and Development Induction in C. elegans

27. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 16 Genes and Development Mouse model for mammalian development Transgenic mice studied Early development of mice and other mammals similar Almost all research in stages leading to implantation Chimera –Organism containing two or more kinds of genetically dissimilar cells from two zygotes

28. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 16 Genes and Development Chimeric mice

29. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 16 Genes and Development Producing a transgenic mouse

30. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 16 Genes and Development Cancer and cell development Cancer-causing oncogenes –Proto-oncogenes –Code for various growth factors or growth factor receptors –Respond to stimulation by growth factors –Cell may misinterpret signal and grow and divide inappropriately Tumor suppressor gene mutation

31. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 16 Genes and Development Cell growth control cascade