AP Bio Chapter 21 Key Terms Flashcards
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 ogranism 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. See also gene cloning.
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.
