Fertilization
See also cell development. Asexual Reproduction Organisms can reproduce without sex. For example, there are species of lizards that consist only of females and reproduce without matting. Such asexual reproduction…
Nervous system
One of the major features of vertebrates which do not have any counterpart in say Drosophila is the formation of a notochord. A picture of this formation is illustrated with the frog, zenopus laevis. Here,…
Fruit fly
Principles of Development as Learned through the Fly Much of the basic principles of has been learned through the fruit fly, Drosophila melanogaster. Some of these basic principles are illustrated here: Importance…
Embryogenesis
Embryogenesis starts out with the fertilized egg which divides or cleaves to form many smaller cells (blastomeres) without any change in total mass. The determinants distributed asymmetrically in the egg…
Cytoskeleton
The cytoplasm of all eukaryotic cells is crisscrossed by a network of protein fibers that supports the shape of the cell and anchors organelles to fixed locations. This network, called…
Chromosomes
Mendelian Inheritance in Man (OMIM): (database of human genetic diseases and genetic variants) See also DNA Introduction/Definitions: When defining the number of chromosomes necessary to define a species, geneticits count…
Voltage gated channels
The plasma membrane of all electrically excitable cells such as neurons contain voltage gated cation channels which are responsible for generating an action potential which is a traveling wave of electrical excitation. An action…
Transmembrane transport proteins
Introduction: Cell membranes are not permeable to all molecules. Small molecules like oxygen and carbon dioxide diffuse rapidly across membranes. Small uncharged polar molecules like water or urea diffuse more…
Cell membranes
Cell membranes consist of a continuous double layer of lipid molecules in which membrane proteins are embedded. Lipids constitute about 50% of the mass of most animal cell membranes with…
Cell cycle control
See also the Cell Cycle See also Cancer Disease Mechanisms See also signal transduction Controling the process of cell division is critical. Loss of this control can lead to cancer. The…