Metazoan Development exam 4

Question Answer
What is ontogeny? the series of developmental phenomena that occurs as the organism progresses toward sexual maturity
What are 2 main processes of gametogenesis? 1. spermatogenesis which produces 4 spermatozoa and 2. oogenesis which produces 1 ovum and 2-3 polar bodies
During spermatogenesis, the ____________ which is _________ undergoes mitosis and produces ________ which then under meiosis spermatogonium. diploid. spermatocytes.
During Oogenesis, the _______ undergoes mitosis and produces ______ which undergo meiosis to make egg cells oogonium. oocytes.
What 3 parts make up a single sperm? 1. head which contains the haploid genome and acrosome with digestive enzymes, 2. neck/midpiece with mitochondria, and 3. tail
What 2 parts make up an egg cell? 1. The cell itself, which has a haploid genome, nutrition and energy reserves for embryo, and the egg itself has polarity. 2. Outer membranes and layers
What are model organisms? They are advantageous for studying aspects of development, usable as external fertilizers and produce many progeny and large eggs.
What 2 membranes make up the ECM of yolk? 1. vitelline membrane and 2. jelly coat
What happens during fertilization? A zygote is produced and diploid state is restored and development is activated
What polarity do humans have? What about other animals? Humans have D-V polarity and other animals have A-V polarity
What is embryogenesis and what 3 phases does it consist of? the process in which the metazoan forms, 3 phases are cleavage, gastrulation, and organogenesis
What is cleavage? A phase of rapid cell division and zygotes that divides to form cells called blastmeres
What are 2 main types of cleavages? Meroblastic cleavage- partial furrow and high yolk content and holoblastic cleavage- entire furrow with moderate yolk content
Cleavage results in the formation of the ______ blastula
What is a blastula? A hollow ball of cells that contains the blastocoel
What is gastrulation? The global reorganization of the embryo
What are the outcomes of gastrulation? The formation of the germ layers and the proper spatial arrangement of germ layers, and establish the body plan
Organisms with 3 germ layers are known as? Organisms with 2 germ layers are known as? Triploblasts and diploblasts
What are the 3 main layers that is formed from the blastoma called? Ectoderm, endoderm and mesoderm
What does the ectoderm form? Epidermal ectoderm and central nervous system
What does the mesoderm form? Muscle connective tissues and coelomic linings
What does the endoderm form? the digestive system epithelium
Organization of germ layers during gastrulation produces what 2 things? 1. the archenteron and 2. the blastopore
In triploblasts, protostomes form what first? the blastopore forms the mouth first and then the anus second
In triploblasts, deuterostomes form what first? the blastopore forms the anus first and then the mouth
How are organs formed? Formed locally within the embryo and each layer is divided into germ layer regions associated with organ contributions
What are indirect developers? A reproductively immature organism that appears dissimilar from mature adult that exists as a larva and undergoes metamorphosis before becoming an adult
What are direct developers? A reproductively immature organism that appears similar to the adult and growth is mainly involved without dramatic changes
What 4 main mechanisms direct the process of embryogenesis? 1. Polarity, 2. morphogenesis, 3. inductive interactions, and 4. restrictions of developmental potential with differentiation as final realization of developmental program
What is polarity? "Instructions" that are segregated in the zygote
What is morphogenesis? Changes in the cell that results in changes in tissue
What is inductive interactions? Communications between cells
What is Cell fate determined by? They become restricted over time and differentiation occurs as a result to make cells specialized for certain purposes
What are determinants primarily used for? They consist of mRNAs and proteins and are equally distributed in the egg and/or distributed to particular regions within the egg
What key piece of evidence shows that the body plan is established at fertilization? The gray crescent
Morphogenesis involves what 3 changes? 1. Changes in cell or tissue shape and 2. changes in cell or tissue adhesion, and 3. changes in the position of cells or tissues within the embryo via migration
What is invagination? The inward buckling of cells to form a pocket
What is involution? The inward rolling of cells over an edge
What is epiboly? The spreading of cells over an external surface
What is ingression? The transition of cells from an epithelial to a mesenchymal state while migrating inward
What is neurulation? The series of morphogenetic events involved in formation of the vertebrate central nervous system
What is adhesion of cells in morphogenesis? It involves the interactions of a cell with other cells and a cell with its extracellular matrix environment
Adhesion is mediated what 2 kinds of transmembrane proteins? 1. Cadherins that mediate cell-cell interactions and 2. integrins mediate cell-ECM contacts with adhesive glycoproteins
Inductive interactions involve _________ _________ in which cells give instructions for development. This involves the use of paracrine signaling called ______ ______ intercellular communications. growth factors.
What experiment did Spemann and Mangold demonstrate? They demonstated the presence of globally-acting inductions in amphibians
What drives limb formation? Localized, reciprocal inductions
What drives limb polarity? Inductive interactions
What is differentiation? Cells becoming specialized for a specific fate and remain that way for the rest of an organism's life.