AP Biology- Genetics

AP Biology- Genetics 1. Character - Definition: A character is a heritable feature that can be observed in an organism. 2. Trait - Definition: A trait is any detectable variation of a specific character. 3. True-Breeding - Definition: True-breeding refers to plants that consistently produce offspring of the same variety when self-pollinated. 4. Hybridization - Definition: Hybridization is the process where an organism carries two different alleles for the same gene. 5. P Generation - Definition: The P generation is the parental generation used in genetic crosses. 6. F1 Generation - Definition: The F1 generation, or first filial generation, consists of the hybrid offspring resulting from the P generation. 7. F2 Generation - Definition: The F2 generation, known as the second filial generation, is produced through the self pollination of F1 hybrids. 8. Alleles - Definition: Alleles are various forms of a gene that can occupy a specific locus on a chromosome. 9. Punnett Square - Definition: A Punnett Square is a graphical tool used to predict the allele composition of offspring from a genetic cross between individuals with known genotypes. 10. Homozygous - Definition: An organism is described as homozygous when it has a pair of identical alleles for a particular character. 11. Heterozygous - Definition: An organism is heterozygous if it possesses two different alleles for a specific gene. 12. Phenotype - Definition: The phenotype refers to the visible traits or characteristics displayed by an organism. 13. Genotype - Definition: The genotype is the genetic constitution of an organism, determining its phenotype. 14. Law of Independent Assortment - Definition: This law stipulates that the segregation of one pair of alleles occurs independently of the segregation of other allele pairs during gamete formation. 15. Rules of Multiplication - Definition: The rules of multiplication state that the probability of two or more independent events occurring simultaneously is found by multiplying the probabilities of each individual event. 16. Rules of Addition - Definition: According to the rules of addition, the probabilities of two or more mutually exclusive events can be determined by summing their individual probabilities. 17. Incomplete Dominance - Definition: Incomplete dominance results in a blended phenotype, such as when a red snapdragon and a white snapdragon produce a pink snapdragon. 18. Codominance - Definition: Codominance occurs when both alleles are expressed equally in the phenotype, for example, an individual with an AB blood type shows expression of both the A and B alleles. 19. Multiple Alleles - Definition: Some traits are determined by multiple alleles at a specific gene locus; an example is the ABO blood group system, which is influenced by three different alleles. 20. Pleiotropy - Definition: Pleiotropy refers to a single gene affecting multiple phenotypic traits, such as the various symptoms caused by sickle-cell anemia from a single pair of alleles. 21. Epistasis - Definition: Epistasis occurs when the expression of one gene is influenced or masked by another gene. For instance, in mice, an allele pair 'cc' results in a white coat, regardless of other alleles that might specify color. 22. Pedigree - Definition: A pedigree is an official record depicting the genetic history of an organism, showing relationships similar to a family tree. 23. Linkage - Definition: Linkage refers to the phenomenon where genes located on the same chromosome tend to be inherited together because they assort as a group during meiosis. For example, flower color and pollen shape genes may be linked on the same chromosome.