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Understanding Animal Development: The Genetic Basis and Processes Involved

This overview explores the fundamentals of animal development, focusing on the three core processes: cell division, differentiation, and morphogenesis. It delves into how cytoplasmic determinants and gene regulation guide early embryonic stages like gastrulation and neurulation. Highlighting the model organism Drosophila melanogaster, the discussion covers the roles of maternal genes, segmentation genes, and homeotic genes in establishing anatomical patterns. Watch informative videos to understand development dynamics and gene expression regulation critical in shaping organisms.

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Understanding Animal Development: The Genetic Basis and Processes Involved

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  1. Chapters 47 & 21 Animal Development & The Genetic Basis of Development

  2. DEVELOPMENT • An organism arises from a fertilized egg as the result of three related processes • Cell division • Cell differentiation • Morphogenesis

  3. How does the ball of cells know when and where to differentiate, fold etc.? Cytoplasmic Determinants !(usually maternal factors like mRNA, proteins, other chemicals) They are non-homogenous

  4. Early Morphogenesis: Gastrulation & Neurulation Neurulation video http://www.youtube.com/watch?v=ZeIyrInOnMc

  5. Fertilization • Gray crescent • Establishing the body axes • What is determination? • What is induction?

  6. REGULATION OF GENE EXPRESSION • Transcriptional regulation is directed by: TRANSCRIPTION FACTORSsuch as: • Maternal molecules in the cell’s cytoplasm (cytoplasmic determinants) • Signals from other cells (induction)

  7. Drosophila melanogaster • Each segment in the adult fly is anatomically distinct • And also has characteristic appendages… just like you? HEAD THORAX ABDOMEN

  8. Drosophila melanogaster • Maternal cytoplasmic determinants • GRADIENTS of chemicals are important • Segmentation genes • Gap genes • Pair rule genes • Segment polarity genes • http://www.youtube.com/watch?feature=endscreen&v=MefTPoeVQ3w&NR=1 • http://www.youtube.com/watch?v=uaedzlrnBGY • http://flymove.uni-muenster.de/Processes/Segmentation/SegPair/SegPairEst/SegPairEstGes.html

  9. HOMEOTIC GENES • Master regulatory genes • Specify the types of appendages and other structures that each segment will form • Mutations produce flies with structures in incorrect places

  10. Normal adult fly Antennapedia mutant Bithorax mutant Examples of Homeotic Mutations

  11. Wild-type Mutants Antennapedia Mutations

  12. HOMEOTIC GENES • are master genes that regulate the expression of numerous other genes • Some of the regulated genes are regulatory themselves

  13. Drosophila DEVELOPMENT REVIEW: Hierarchy of Gene Activity • Maternal genes in cytoplasm of the egg • Segmentation genes of embryo • Gap genes • Pair-rule genes • Segment polarity genes • Homeotic genes of the embryo • Other genes of the embryo

  14. HOMEOTIC GENES • all possess homologous segments • 180-nucleotide sequence = homeobox (HOX) • Which encodes 60-amino-acid homeodomain

  15. Homeodomain • Homeotic genes • encode for transcription factors that influence other developmental genes • all have a hox region (homeobox) • which folds into a protein called the homeodomain. • Homeodomain is the DNA Binding region of the transcription factor

  16. HOMEOTIC GENES • Vertebrate genes homologous to the homeotic genes of Drosophila have maintained their chromosomal arrangement

  17. Ultrabithorax • Other interesting gene names in Drosophila http://jpetrie.myweb.uga.edu/genes.html Regulatin’ Genes song for fun: http://www.youtube.com/watch?v=9k_oKK4Teco

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