BIOL 443 Lecture Notes - Lecture 1: Symmetry In Biology, Cell Growth, Zygote
Document Summary
Fertilization: the fusion of gametes which are the mature (normally haploid) sex cells. Cleavage: series of extremely rapid mitotic divisions that immediately follow fertilization. Is not accompanied by cell growth or change in size of the embryo. It stays the same size there are just more cells inside it: blastomeres- cells of cleavage stage, morula- a solid ball of cells created by cleavage, blastula- the final product of cleavage, the embryo in a spherical structure. Gastrulation (gastrula stage: cell division slows down and cells undergo lots of movement and rearrangements, these movements determine symmetry, orientation, and location of axes, they also form the 3 major germ layers. Ectoderm (outside), mesoderm (middle), and endoderm (inside) Organogenesis: the formation of major organs and tissues from the 3 germ layers. Metamorphosis (in some organisms: the change from a sexually immature form (larva) to an adult form, often times the larva bears little or no resemblance to the adult.
