Developmental Biology
  1. Consider an experiment in which Agrobacterium is the mode of DNA transfer into the plant cell. Plant leaves are cut into pieces of 10.2x10.2mm and soaked in a liquid containing suspended Agrobacterium for 11 minutes. This will result into a development of new cells due to the induction of DNA into the cells by the bacterium. Placing the plants on a media that allows root development and shooting, the plants grows again.
  2. When yeast cells, subject to induction, are exposed to basic cations such as lithium cations, the cells begin to absorb DNA.   
  3. The factors are:
  • Presence of receptor is mandatory
  • Presence of signal transduction pathway is mandatory
  • For the cell to respond some inhibitors may be removed
  • The responding tissue may be active during a particular developmental period.

The growth of the leaf at the tip of the plant is under influence of hormones rather than the genes. The hormone auxin accumulates at the leaf tip to initiate a continuous growth.

  1. Mitochondria- are part of the cell that aids in respiration. Its competence is measured by the ability to provide adequate amount of ATP. Cell Membrane is the covering layer of the cell that protects the inner components of the cell. Chloroplasts help in photosynthesis while nucleus comprises the nucleus. Competence occurs with transformation of integrated DNA at the ectopic sites in the chromosome.
  2. Signal transduction occurs when a cell surface receptor is activated by extracellular signaling molecules.
  3. The tissues involved in the induction of chick epidermal structure are the optic vesicle that develops to give rise to retina tissues.  In drosophila the major tissue involved in induction are the visual and olfactory cells. Both the tissues are involved in the development of lens that aids visibility.
  4. Mouse with a RAF protein is likely to suffer defects in the development of placenta, skin and lung. They also experience defects in the survival and differentiation of vascular epithelial cell resulting into embryonic death of the mouse.
  5. Mutation in the MEK proteins results into a reduced level of crystallin proteins leading to defects in the formation of the lens.
  6. The Notch Pathway: it occurs when a single cell binds to its receptor on the adjacent sell. The binding causes a change in the intracellular domain of the Notch leading to the activation of the protease. The protease then cleaves the notch leading to the entry of the intracellular region of the Notch protein into the nucleus. This activates activities of the nucleus by transcribing the target genes.   The extracellular matrix: aids on the developmental events since the adhesion and migration of the cell depends on the capability of the cell to form links with the extracellular matrices.
  7. The interaction between cells starts with the synthesis of the signaling molecule by the signaling cell, which then releases the signaling molecule. The molecule is then transported to the cell of target, which is detected by a receptor protein initiating cellular metabolism in the target cell. The process ends with the termination of the cellular response.
  8.  RGD is an abbreviation of Arginine-Glycine-Aspartic acid. It aids in the development of the lung by binding integrins in the branching morphogenesis of the mammalian lung.
  9. Connexins are trans-membrane proteins that converge to form gap junction in vertebrate. It helps in the development and functioning abilities of Cerebellum.
  10. Receptor Tyrosine Kinase (RTK) is a receptor found on the surface of a cell and whose affinity towards the polypeptides such as hormones is very high. RTKS catalyses cell proliferation, differentiation, and cell migration. It undergoes auto-phosphorylation on specific tyrosine residues and interacts with adaptor proteins to make the intracellular transduction pathways active in the kidney development.
  11. Smad are proteins responsible for transducing nodal signals into the nucleus. They form a path by which the nodal signals enters the nucleus thereby activating the genes targeted by the nodal signals and facilitate the development of cardiac embryo through the cardiovascular differentiation.  
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