BIOL 111 Lecture Notes - Lecture 12: Monogenea, Sexual Reproduction, Diploblasty

• School: McGill University
• Department: Biology (Sci)
• Course: BIOL 111
• Professor: Rudiger Krahe

Document Summary

Biol 111 lecture 12 embryonic development and symmetry; cnidarians and. Embryonic development: zygote: diploid cell resulting from union of 2 haploid gametes; 1st cell of next generation, embryo: young animal or plant while in a protective structure. 2 major processes occur in during embryonic: cleavage = first cell divisions in the embryo, forming many cells from one cell, gastrulation = in-folding, invagination, process embryonic tissue layers (2-3) from the 1st layer. Types of symmetry: asymmetrical, no axis divides body into equal halves ex. Sponges: radially symmetrical, along 1 axis as long as one cuts through centre, body can be divided in equal halves from many angles, ex. Sea anemone: bilaterally symmetrical, single axis divides body into equal halves, midsagittal plane (between eyes) 11 000 species: diploblastic, nervous and muscular. Body forms: polyp (sessile, medusa (motile) tissue. Cnidarians have a simple nervous system: sensory information can come in from any direction.