Cell Division: separation of a cell into two daughter cells. In higher eukaryotes, it involves division of the nucleus (mitosis) and of the cytoplasm (cytokinesis); mitosis is often used to refer to both nuclear and cytoplasmic division.
Cell Lineage: A pedigree of cells related through division that enable one to trace a cell’s predecessors and progeny.
Chromosome: in eukaryotes, the structural unit of the genetic material consisting of a single, linear double-stranded DNA molecule and associated proteins wrapped into a high order structure. During mitosis, chromosomes condense into compact structures visible in the light microscope. In prokaryotes, a single circular double-stranded DNA molecule constitutes the bulk of the genetic material.
Differentiation: process usually involving changes in gene expression by which a precursor cell becomes a distinct specialized cell type.
Embryo: the early developmental stage of an organism (C. elegans in this case) after fertilization and before hatching.
Embryogenesis: developmental process of an individual from a fertilized egg (zygote) to hatching.
Hermaphrodite: hermaphrodite is the form that can make both sperm and oocytes and can self-fertilize. C. elegans has both hermaphrodites and males. The male can mate with hermaphrodites to produce cross progeny.
Larva (Larvae): The immature forms of C. elegans. After hatching, C. elegans undergo a series of larval stage, called L1 – L4, before becoming adults.
Membrane: permeability barrier surrounding cells or organelles and consists of a phospholipids bilayer, together with associated membrane proteins.
Microtubule: long, cylindrical polymer composed of the protein tubulin. It is one of the three major classes of filaments in the cytoskeleton.
Mitotic spindle: array of microtubules and associated proteins that forms between the opposite poles of a eukaryotic cell during mitosis and serves to move the duplicated chromosomes apart.
Model Organism: organisms used to closely study and elucidate our understanding of basic biological phenomena that might not be easily researched in advanced organisms. In general, they possess characteristics such as small size, short life span and ease of cultivation.
Mutant: a cell microorganism that manifests new characteristics due to a change in its genetic material.
Nematode: nematodes, or roundworms, are generally slender worms, circular in cross section. They are remarkably uniform in structure but vary a lot in size and way of life. Some live as parasites in other animals; some are parasites of plants and some live free in soil, marine mud and decaying organic matter.
Nuclei: the eukaryotic organelle containing DNA together with transcriptional machinery. DNA is organized into chromosomes. Prior to cell division chromosomes are replicated and then condense, at which time the nuclear membrane breaks down.
Proliferation: the increase in the number of cells or offspring.
Pro-nuclei meeting: the developmental stage where pro-nuclei that are migrating from opposite ends of the fertilized zygote meet.
Pro-nucleus: one of two haploid nuclei in a newly fertilized embryo (one maternal and one paternal) (Adapted from The Cell A Molecular Approach. Geoffrey M. Cooper 1997)
Specimen: any animal or plant, or any part, product, egg, seed or root of any animal or plant. For example: C. elegans embryos can be specimens that one can look at with light microscopy.
Spindle: see mitotic spindle.
Strain: a pure breeding lineage.
Wild type: normal, nonmutant form of an organism; the form found in nature (in the wild).
Worm: is the nickname of C. elegans (Caenorhabditis elegans) .
Zygote: a fertilized egg; diploid cell resulting from fusion of a male and female gamete.
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