Chapter 22: Descent with Modification * Natural Selection: Is a process in which individuals with certain inherited traits leave more offspring than individuals with other, less beneficial traits. * Evolutionary Adaptation: The process by which a population becomes better suited to its habitat. * Evolution: Descent with modification; Darwin's proposal that Earth's many species are descendants of ancestral species that were different from the present-day species. * Taxonomy: The science of technique of classification. * Fossils: A preserved remnant or impression of an organism that lived in the past. * Sedimentary rock: Formed from the sand and mud that settle to the bottom of seas, lakes, and marshes. * Paleontology: The study of fossils. * Catastrophism: Speculating that each boundary between strata represents a catastrophe. * Gradualism: Idea that profound change can take place through the cumulative effect of slow but continuous processes. * Uniformitarianism: the same geologic processes are operating today as in the past, and at the same rate. * Descent with modification: a phrase that summarized his views of life. * Artificial selection: modification of other species over many generations though selecting and breeding individuals that possess desirable traits. * Homology: certain characteristics in related species have an underlying similarity even though they may have very different functions. * Homologous structures: represent variations on a structural theme that was present in their common ancestor. * Vestigial organs: structures of marginal, if any, importance to the organism * Biogeography: Darwin’s observations of the geographic distribution of species. * Endemic: Which means they are found nowhere else in the world.
Ivanna Buraye
Period:3
3/8/12
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CHAPTER 21: THE GENETIC BASIS OF DEVELOPMENT * Model organism: organism chosen for study * Cell differentiation: cells become specialized in structure and function * Morphogenesis: the physical processes that give and organism its shape and constitute * Apical Meristems: the structure responsible for a plant’s continual growth and formation of new origins * Totipotent: describing a cell that can give rise to all parts of an organism * Cloning: making a genetically identical individual * Clone: each individual made in this way of cloning * Stem cell: unspecialized cell that can divide during a single division into one identical daughter cells * Pluripotent: able to give rise to multiple but not all cell types. * Determination: progressive restriction of developmental potential, causing the possible fate of each cell to become more limited as the embryo develops * Cytoplasmic determinants: the maternal substances in the egg that influences the course of early development by regulating the expression of genes that affect the developmental fate of cells * Induction: the signal molecules cause changes in nearby target cell * Pattern formation: the developmental of a spatial organization in which the tissues and organs of an organism are all in their characteristic places * Positional Information: signals to which genes regulating development respond, indicating a cell’s location relative to other cells in an embryonic structure. * Embryonic lethal: mutations with phenotype causing death at the embryonic or larval stage * Maternal effect gene: results in a mutant phenotype in the offspring, regardless of their one genotype * Egg-polarity genes: another name for a maternal effect gene, a gene that helps control the orientation of the egg * Morphogens- a substance, such as bicoid protein, that provides positional information in the form of a concentration gradient along on embryonic axis. * Segmentation genes: gap genes, pair rules genes, segment polarity *
