ZOOHCC - 601: Developmental Biology (Theory)
Unit 1: Introduction
Historical perspective and basic concepts
Developmental biology is the study of the processes by which organisms grow and develop from a single cell to a complex multicellular organism. It is a field that has been studied for centuries, and its history can be traced back to ancient Greek philosophers.
The Greek philosopher Aristotle is credited with being one of the first people to study embryology. He observed the development of chicks inside eggs and proposed a theory of epigenesis, which suggested that the development of an organism is the result of a series of progressive changes in a pre-existing structure.
In the 17th century, the Dutch scientist Antonie van Leeuwenhoek was the first person to observe the fertilization of an egg by a sperm, using a primitive microscope. This discovery laid the foundation for the study of embryonic development.
In the 18th and 19th centuries, many scientists made significant contributions to the field of developmental biology. The French naturalist Georges Cuvier was the first to suggest that there were distinct stages in the development of an embryo. The German scientist Carl Ernst von Baer observed that embryos of different species share common features during development, a concept known as von Baer's law.
In the 20th century, the field of developmental biology underwent a revolution with the discovery of DNA and the development of molecular biology techniques. In the 1950s, the American scientist James Watson and the British scientist Francis Crick proposed the double helix structure of DNA, which provided a mechanism for the transmission of genetic information from one generation to the next.
Today, developmental biology is a thriving field with many sub-disciplines, including embryology, genetics, cell biology, and evolutionary biology. It has led to significant advances in our understanding of how organisms develop, and has practical applications in fields such as regenerative medicine and biotechnology.
Basic concepts of development biology
In developmental biology include cell differentiation, morphogenesis, embryogenesis, gene expression, signaling pathways, homeostasis, and evolution. Cell differentiation is the process by which cells become specialized in structure and function, while morphogenesis is the process by which cells organize into tissues and organs, forming the shape and structure of an organism. Embryogenesis is the process by which a single cell, the zygote, divides and differentiates into all the cells and tissues that make up an embryo. Gene expression is the process by which genetic information encoded in DNA is converted into proteins or RNA molecules that perform specific functions in cells. Signaling pathways are the networks of molecules and biochemical reactions that transmit information between cells, regulating their behavior and controlling the development and function of tissues and organs. Homeostasis is the maintenance of a stable internal environment within an organism, while evolution is the process by which genetic changes accumulate over time, leading to the emergence of new species and the diversification of life on Earth.
