s 3 main arguments (lecture & p. 62). 1)There is genetic variation in species 2)Some genes are more advantageous than others 3)That variation allows for adaptation (natural selection)What are some sources of genetic variability (lecture & text)? Sexual reproduction (meiosis), natural selection, mutation, crossing-over, patterns of mating, etc.Define natural selection (p. 63), mutation (p. 70), genotype, phenotype (p. 67), meiosis, mitosis (p. 65 & Table 3.1, p. 66), crossing over (p. 66), dominant characteristic & recessive characteristic (text & also Table 3.2, p 68), incomplete dominance, co-dominance (p. 69), carrier, sex-linked, poly-genetic (p. 70), single gene, chromosomal abnormalities (70-71 & lecture) and know examples of each (see Table 3.3, p. 72). Natural selection: The evolutionary principle that individuals who have characteristics advantageous for survival in a particular environment are most likely to survive and reproduce. Over many generations, this process of “survival of the fittest” will lead to changes in a species and the development of new species.
Mutation: A change in the structure or arrangement of one or more genes that produces a new phenotype.Genotype: the genetic makeup a person inherits Phenotype: the characteristics or traits the person eventually has; The way in which a person's genotype is expressed in observable or measurable characteristics.Meiosis: The process in which a germ cell divides, producing sperm or ova, each containing half of the parent cell’s original complement of chromosomes; in humans, the products of meiosis normally contain 23 chromosomes.Mitosis: The process in which a cell duplicates its chromosomes and then divides into two genetically identical daughter cells.Crossing over:A process in which genetic material is exchanged between pairs of chromosomes during meiosis.Dominant characteristic [dominant gene]: A relatively powerful gene that is expressed phenotypically and masks the effect of a less-powerful recessive gene. ex. Huntington’sRecessive characteristic [recessive gene]: A less powerful gene that is not expressed phenotypically when paired with a dominant gene; ex. PKU, Sickle Cell Incomplete dominance: A condition in which a stronger gene fails to mask all the effects of a weaker partner gene; a phenotype results that is similar but not identical to the effect of the stronger gene.