Chapter 21 Vocabulary
- Apical Meristem
- Embryonic plant tissue in the tips of roots and in the buds of shoots that supplies cells for the plant to grow in length.
- Apoptosis
- The changes that occur within a cell as it undergoes programmed cell death, which is brought about by signals that trigger the activation of a cascade of suicide proteins in the cell destined to die.
- Cell Differentiation
- The structural and functional divergence of cells as they become specialized during a multicellular organism’s development; dependent on the control of gene expression.
- Cell Lineage
- The ancestry of a cell.
- Chimera
- An organism with a mixture of genetically different cells.
- Clone
- (1) A lineage of genetically identical individuals or cells. (2) In popular usage, a single individual organism that is genetically identical to another individual. (3) As a verb, to make one or more genetic replicas of an individual or cell.
- Cloning
- Using a somatic cell from a multicellular organism to make one or more genetically identical individuals.
- Cytoplasmic Determinants
- The maternal substances in the egg that influence the course of early development by regulating the expression of genes that affect the developmental fate of cells.
- Determination
- The progressive restriction of developmental potential, causing the possible fate of each cell to become more limited as the embryo develops.
- Egg-Polarity Gene
- Another name for a maternal effect gene, a gene that helps control the orientation (polarity) of the egg.
- Embryonic Lethal
- A mutation with a phenotype leading to death at the embryo or larval stage.
- Homeobox
- A 180-nucleotide sequence within homeotic genes and some other developmental genes that is widely conserved in animals. Related sequences occur in plants and prokaryotes.
- Homeotic Gene
- Any of the genes that control the overall body plan of animals and plants by controlling the developmental fate of groups of cells.
- Induction
- The ability of one group of embryonic cells to influence the development of another.
- Maternal Effect Gene
- A gene that, when mutant in the mother, results in a mutant phenotype in the offspring, regardless of the genotype.
- Model Organism
- An organism chosen to study broad biological principles.
- Morphogen
- A substance, such as Bicoid protein, that provides positional information in the form of a concentration gradient along an embryonic axis.
- Morphogenesis
- The development of body shape and organization.
- Organ Identity Genes
- Plant homeotic genes that use positional information to determine which emerging leaves develop into which types of floral organs.
- Pattern Formation
- The ordering of cells into specific three-dimensional structures, an essential part of shaping an organism and its individual parts during development.
- Pluripotent
- Describing a stem cell, from an embryo or adult organism, that can give rise to multiple but not all differentiated cell types.
- Positional Information
- Signals to which genes regulating development respond, indicating a cell’s location relative to other cells in an embryonic structure.
- Segmentation Gene
- A gene of the embryo that directs the actual formation of segments after the embryo’s axes are defined.
- Stem Cell
- Any relatively unspecialized cell that can divide during a single division into one identical daughter cell and one more specialized daughter cell, which can undergo further differentiation.
- Totipotent
- Describing a cell that can give rise to all parts of an organism.
