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Rediscovering Biology: Molecular to Global Perspectives

Genetics of Development

Organisms as different as flies, fish, and humans share genes with remarkable similarity that guide development. This unit explores new understanding of these molecules and processes, and examines how they work to coordinate– or misdirect– the formation of an entire organism.

ONLINE TEXTBOOK
The online textbook chapters support and extend the content of each video. The Web version can be viewed as a full chapter or as individual sub-sections, and includes links to glossary terms and other related material.

ANIMATIONS & IMAGES
Explore the archive of animations, images and figures from the videos and online textbook. All of the images can be viewed online or downloaded as jpg files.

EXPERT INTERVIEW TRANSCRIPTS
Read profiles of the expert scientists featured in the video and find the complete transcripts of the interviews conducted for this unit.
Judith Eisen, Ph.D.
Markus Grompe, M.D.
John Incardona, Ph.D.
Nipam Patel, Ph.D.
John Postlethwait, Ph.D.

Chapter Contents

Genes and Development
Differentiation and Genetic Cascades
The Details of Gene Expression
Establishing the Gradient and Coordinate Genes
Responses to the Concentration Gradient
Homeotic Genes
Cell Lineage Mapping and C. Elegans
Fate Maps
Cell-Cell Communication and Signal Transduction
Conservation of the Homeobox
Conservation of the “Control Switch” Gene for Eyes
A Brief Look at Plant Development
Stem Cells
Coda

Unit Glossary

Coordinate Genes
Genes that set the coordinate system, the primary anterior-posterior and dorsal-ventral axes, of the early embryo.

Developmental Pathway
A sequence of genes that underlie a developmental process.

Differentiation
The process by which cells specialize during development.

Ectopic expression
Expression (transcription and translation) of a gene at a time or place where it is normally not expressed.

Fate Map
The diagrammatic representation of the cells in the embryo and the eventual type of tissue they will become in the adult.

Homeobox
A 180 nucleotide section of DNA that codes for a specific class of DNA-binding proteins. First found in the homeotic genes of Drosophila melanogaster.

Homeotic genes
Early developmental genes that specify segment identity.

Maternal effect
The condition where the phenotype is determined not by the individual’s own genotype but by its mother’s genotype.

Motifs
A short region in a protein sequence, which is conserved in many proteins.

Multipotent
Cells that can produce a defined set of cell types.

Pluripotent
Cells that can produce most, but not all, types of cells of the adult organism.

Programmed Cell Death
Death of cells that is part of the normal process of development of an organism.

Regulatory element
Sequences near the coding regions of genes to which transcription factors can bind, thus influencing transcription.

Transgenic organismAn organism that contains hereditary information from two different species of organisms.

Transcription factor
A protein that influences transcription of another gene by binding to DNA.

Unit Animations

  • Hedgehog Gradient
    The level of Hedgehog protein a cell binds during development can influence its fate.
    View Quicktime Movie
  • Hedgehog Signaling
    The Hedgehog signaling pathway triggers expression of other developmentally important genes.
    View Quicktime Movie
  • Homeobox
    The color-shaded regions represent homeotic genes called Hox genes. The dark band within each gene represents a 180-base-pair region called the homeodomain.
    View Animation Still
  • Homeodomain
    A 3-D model of a protein with a homeodomain, a “helix-turn-helix” motif that acts as a transcription factor by binding directly to DNA to turn on other genes.
    View Quicktime Movie
  • Retinoic Acid
    A retinoic acid gradient controls the activation of many developmentally important genes. Disruptions in the embryo’s retinoic acid levels can lead to malformation of the embryo.
    View Quicktime Movie
  • Spatial and Temporal Colinearity
    Hox genes display spatial colinearity — genes at one end of the chromosome are expressed at the head end of an embryo while genes at the other end are expressed toward the tail end. Vertebrate Hox genes also show temporal colinearity — genes at the head end are expressed before those at the tail end.
    View Quicktime Movie

Related Resources

Books
Hartl, D. L., and E. W. Jones. 2001. Genetics: Analysis of genes and genomes. 5th ed. Sudbury, MA: Jones and Bartlett.
A college-level textbook on the principles of genetics; includes an overview of the genetic control of development.

Griffiths, A. J. F., J. H. Miller, D. T. Suzuki, R. C. Lewontin, and W. M. Gelbart. 2000. An Introduction to genetic analysis. 7th ed. New York: W. H. Freeman and Company.
A textbook that provides more in-depth, but somewhat more difficult coverage, of developmental genetics.

Raff, R. C. 1996. The shape of life: Genes, development, and the evolution of animal form. Chicago: University of Chicago Press.
A look at the evolution of development.

Series Directory

Rediscovering Biology: Molecular to Global Perspectives

Credits

Produced by Oregon Public Broadcasting. 2003.
  • ISBN: 1-57680-733-9