Somethin

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  • Topic: DNA, Genetics, Gene
  • Pages : 5 (1667 words )
  • Download(s) : 85
  • Published : December 7, 2012
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1. Allele-One of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome Example: Most multicellular organisms have two sets of chromosomes, that is, they are diploid Example: Allelic variation at a locus is measurable as the number of alleles present, or the proportion of heterozygotes in the population. 2. Gene-A unit of heredity that is transferred from a parent to offspring and is held to determine some characteristic of the offspring Example: Genes hold the information to build and maintain an organism's cells and pass genetic traits to offspring, Example: All organisms have many genes corresponding to various biological traits, some of which are immediately visible, such as eye color or number of limbs 3. Genotype-The genetic constitution of an individual organism. Example: Non-hereditary DNA mutations are not classically understood as representing the individual's genotype Example: a genotype typically implies a measurement of how an individual differs or is specialized within a group of individuals or a species 4. Phenotype-The set of observable characteristics of an individual resulting from the interaction of its genotype with the environment. Example: Not all organisms with the same genotype look or act the same way because appearance and behavior are modified by environmental and developmental conditions. Example: Phenotypic variation is a fundamental prerequisite for evolution by natural selection 5. Punnett square-The Punnett square is a diagram that is used to predict an outcome of a particular cross or breeding experiment Example: The Punnett Square is visual representation of Mendelian inheritance. Example: is used by biologists to determine the probability of an offspring's having a particular genotype 6. Dominant-Relating to or denoting heritable characteristics that are controlled by genes that are expressed in offspring even when inherited from only one parent Example: Each chromosome of a matching pair is structurally similar to the other, and each member of a homologous pair has the same genetic material arranged in the same order and physical locations Example: The genetic material in each chromosome comprises a series of discrete genes that influence various traits 7. Recessive-Relating to or denoting heritable characteristics controlled by genes that are expressed in offspring only when inherited from both parents Example: is only seen in a homozygous genotype

Example: never in a heterozygous genotype.
8. F1 generation-The first generation of a genetic cross. Example: In fish breeding, those parents frequently are two closely related fish species, while in plant and animal genetics those parents usually are two inbred lines Example: Mules are F1 hybrids between horse and donkey.

9. F2 generation-The second filial generation. The offspring resulting from a cross of F1 Generation plants. Example: does not have the consistency of the F1 hybrid
Example: it may retain some desirable traits and can be produced more cheaply as no intervention in the pollination is required 10. Heterozygous-Possessing two different forms of a particular gene, one inherited from each parent Example:  Heterozygous genotypes are represented by a capital letter (representing the dominant allele) and a lowercase letter in the punett square Example: a heterozygote will express only the trait coded by the dominant allele and the trait coded by the recessive allele will not be present 11. Homozygous- Possessing similar forms of a particular gene, one inherited from each parent Example: True breeding organisms are always homozygous for the traits that are to be held constant. Example: An individual that is homozygous-recessive for a particular trait carries two copies of the allele that codes for the recessive trait. 12. Monohybrid cross- a method of tracking the inheritance pattern of a single trait between two individual organisms....
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