| A | B |
|---|
| allometric growth | as body size increases, relative proportions of body parts changes |
| animal pole | end of egg that roughly marks the site of the future mouth |
| antero-posterior axis | line drawn from head to tail |
| apoptosis | programmed cell death |
| asymmetric divisions | cell division that partitions cytoplasmic determinants unequally |
| axes | imaginary lines that lay out the basic directions in the body |
| blastocoel | fluid-filled cavity in early embryo |
| blastopore | site of invagination of cells during gastrulation |
| blastula | embryo that is a ball or disk of cells with an internal fluid filled cavity |
| body plan | anatomical arrangement of organism |
| cell differentiation | restriction of cell fate/potential during development |
| cell lineage | all of the cells that give rise to any individual cell in an organism |
| cell signalling | the way that intercellular information is generated and perceived |
| cleavage | cell division |
| competence | ability to respond to a signal |
| cytoplasmic localization | presence of a molecule in the cytoplasm of a cell |
| determinants | materials that generate morphogenic or positional signals |
| diffusion | movement of molecules from an area of high concentration to low concentration |
| diploid | having two copies of each type of chromosome |
| direct contact | impacting immediately neighboring cells |
| dorso-ventral axis | line drawn from back to front |
| ectoderm | germ layer giving rise to skin, nervous system and neural crest |
| embryo | developmental stage from 2-cell to fetal stage |
| endoderm | germ layer that gives rise to many cell types of abdominal organs |
| fate | cell type an embryonic cell will give rise to if not disturbed |
| gap junction | open channel between cells in which each cell donates half of the channel |
| gastrulation | stage of development generating trilaminar embryo |
| genotype | exact genetic makeup of an organism |
| germ layers | three basic sheets of cells generated during gastrulation |
| gradient | concentration pattern of a material in a system |
| haploid | genome composed of one of each type of chromosome |
| induction | production of morphogen by one tissue that changes developmental property of responding tissue |
| lateral inhibition | hormone made by one cell prevents formation of structure in the vicinity of that cell |
| meiosis | nuclear division that generates haploid reproductive cells in sexual reproduction |
| mesoderm | germ layer that gives rise to connective tissue in the embryo |
| mitosis | nuclear division that results in exact duplicates of parental cells |
| morphogen | hormone produced in an embryo that changes developmental property of target cell |
| mRNA | RNA used as a template to make protein |
| neural crest | amoeboid cells that stream away from site of neural tube closure |
| neural tube | closed hollow nerve cord |
| neurula | embryo in which nerve tube is separating from cutaneous ectoderm |
| neurulation | embryonic stage in which dorsal nerve cord separates from cutaneous ectoderm |
| notochord | rod of connective tissue that induces formation of nerve tube in chordates |
| organizer | region of embryo that directs a major stage of embryogenesis (i.e. gastrulation) |
| phenotype | physical appearance of an organism |
| positional information | developmental directions given to cell based on its location in embryo |
| positional value | information for development of a structure based on position of cell(s) |
| post-transcriptional modification | change in chemical structure of a protein after it has been synthesized |
| regulation | ability of embryo to fill in missing information to make whole embryo |
| mosaicism | inability of embryo to fill in missing information to make whole embryo |
| somatic cells | non-reproductive cells in organism |
| somites | brick-like mass of mesoderm found along nerve cord and notochord |
| specification | cell potential restricted so it will form a characteristic structure in culture |
| determination | cell potential restricted so it will develop into a characteristic structure if transplanted |
| threshold concentration | critical concentration above (or below) which a characteristic developmental event will occur |
| transcription | process of DNA-dependent RNA synthesis |
| transcription factors | proteins that increase likelihood that RNA polymerase will bind to promoter |
| translation | RNA-dependent protein synthesis |
| vegetal pole | end of egg that roughly marks position of anus |
| zygote | fertilized egg |
