Developmental Biology

What is the process called by which a single fertilized egg develops into a multicellular organism with specialized tissues and organs? Embryogenesis What role does the notochord play in early vertebrate development? It induces the formation of the neural tube by signaling to the overlying ectoderm. How does gastrulation contribute to the development of the three germ layers? Gastrulation reorganizes the blastula into a three-layered structure, forming the ectoderm, mesoderm, and endoderm. What are the key molecular signals involved in the formation of the dorsal-ventral axis in vertebrates? Signals like BMP (Bone Morphogenetic Proteins) and their antagonists (e.g., Noggin, Chordin) are essential for establishing the dorsal-ventral axis. How do Hox genes contribute to the patterning of body segments in an embryo? Hox genes encode transcription factors that regulate the identity and development of specific body segments along the anterior-posterior axis. What is the significance of the organizer region in amphibian embryos? The organizer region, such as Spemann's organizer, directs the development of surrounding cells and helps establish the body plan, including the dorsal axis. What are somites, and how do they contribute to vertebrate development? Somites are segmented blocks of mesoderm that give rise to structures such as vertebrae, ribs, and associated muscles. How does lateral inhibition contribute to the formation of specialized cells in a developing tissue? Lateral inhibition ensures that neighboring cells adopt different fates by using signaling pathways like Notch-Delta to suppress similar differentiation. What is the role of the extracellular matrix (ECM) during cell migration in embryonic development? The ECM provides structural support and biochemical signals that guide migrating cells to their target locations. How does the process of neurulation lead to the formation of the central nervous system? Neurulation involves the folding of the neural plate into the neural tube, which later differentiates into the brain and spinal cord. What is the function of morphogens in establishing positional information in a developing embryo? Morphogens are signaling molecules that form concentration gradients, instructing cells to adopt specific fates based on their position within the gradient. What is the significance of apoptosis during limb development? Apoptosis removes cells in specific regions, such as the interdigital areas, to sculpt the final shape of the limb. How does the process of induction influence the fate of embryonic cells? Induction occurs when one group of cells influences the development of another through signaling molecules or direct contact. What mechanisms underlie the asymmetry of the left-right axis in vertebrates? Nodal signaling and cilia-driven fluid flow at the node help establish left-right asymmetry during development. What is the role of epiboly during zebrafish development? Epiboly is the spreading and thinning of the blastoderm over the yolk to enclose it completely. How do germline cells become specified during development? Germline cells are specified by cytoplasmic determinants or signaling pathways that segregate them from somatic lineages. What is the role of Wnt signaling in embryonic development? Wnt signaling regulates processes such as axis formation, cell proliferation, and differentiation during embryogenesis. What is the process of somitogenesis, and how is it regulated? Somitogenesis is the periodic formation of somites from the presomitic mesoderm, regulated by the segmentation clock and gradients of FGF and Wnt signaling. How does the neural crest contribute to the development of diverse structures in vertebrates? Neural crest cells migrate to various parts of the embryo, differentiating into structures such as peripheral nerves, melanocytes, and craniofacial cartilage. What is the role of planar cell polarity (PCP) in tissue organization? PCP ensures the coordinated orientation of cells within the plane of a tissue, crucial for processes like convergent extension and ciliogenesis. What is developmental Biology? the biological discipline aimed at understanding how a single-celled zygote (fertilized egg) becomes a new multicellular organism Developmental biology is concerned with... how genotype is manifested as phenotype What does the question of differentiation ask in Developmental Biology? How does a single celled zygote give rise a multicellular organism? What does the question of Morphogensis ask in developmental biology? How do cells form their correct shapes and organize into tissues, organs, organisms... What does the question of Growth ask in Developmental Biology? How do cells "know" when to stop dividing? What does the question of Environmental Integration ask in Developmental Biology? How does an organism's environment affect its development? What does the question of Evolution ask in Developmental Biology? How does changes in developmental patterns over time give rise to new body forms/species? There is no what during cleavage? growth What is cell fate? The characteristics of cell type (or types) that an early embryonic cell will normally give rise to What is a fate map? the summation of the cell fates for many of the cells of an embryo at a particular stage of development What are the three methods of fate mapping? 1. Transplantations 2. Ablations (of the cells) 3. Labels and Dyes (laser activated florescent dye) What did Hans Driesch do? used sea urchins to study development, discovered that cells under pressure during cleavage develop the same as normal cells (regulative development) What did William Roux do? used mosaic development by deadening one cell What is differentiation? involves overt changes in cellular biochemistry and function What is specification? the ability of cells to adopt their normal fate when isolated from the embryo (it is labile so it can be reversed) What is determination? the ability of a cell to develop according to its original fate when placed into another region in the embryo (it is stable and can not be reversed) What is autonomous specification? differential acquisition of cytoplasmic molecules (cell fate determinants) determined in the egg (says lineage/ inheritance matters) What is conditional specification? it says that position/neighborhood matters What are maternally synthesized mRNAs? are made and stored in the oocyte so they can be present in the egg at fertilization What are zygotically synthesized mRNAs? are expressed in the developing embryos What is induction? an interaction between one cell or tissue (inducer) and another cell or tissue (responder) which results in the responding tissue changing properties What are the three mechanisms of induction? Juxtacine signal (physical interaction), paracrine factors (diffusion), and paracrine signal (mix of two) What is the relationship between regulative vs mosaic development? First take home assignment Who came up with the preformation theory and what was it? Malpighi. Stated that "all structures are present in the embryo" (ancient times to 1760s) Who came up with the homonculus?