3 DNA Deoxyribonucleic Acid The major nucleic acid in organisms Carries genetic information and is responsible for the transmission of traits.
4 GeneA segment of DNA that codes for a specific trait in an organism.
5 Allele An alternative form of a gene/trait. Example: Eye color alleles are blue, green, hazel, brownCan be homozygous or heterozygous
6 Homozygous Allele Organism with identical alleles for a given trait Can be dominant or recessiveExample: TT or tt
7 Phenotype The physical appearance of a trait in an organism Determined but not always indicative of the genetic makeup of the organismExample: tall or short
8 Genotype The genetic composition of an organism for a given trait Often cannot be determined by looking at an organismExample: Tt or TT, both are tall
9 Recessive Gene/Allele Variation of a trait that can only be expressed in the absence of a dominant alleleHeterozygous individuals are carriers for recessive alleles.
10 Dominant Gene/AlleleVariation of a trait that is expressed over other variations of the same traitMost common forms in natural populationsSome traits can be co-dominant or exhibit incomplete dominance
11 ChromosomeLong condensed strand of DNA forming in the nucleus of a cell prior to cell divisionForm cells that when split, create an exact copy of DNA in the daughter cell
12 Chromatid PairsX-shaped structures that serve as the mechanism for the transmission of genetic material during cell division.They are pulled apart in the process of mitosis and meiosis.
13 Heterozygous Allele Organism with different alleles for a given trait Example: Tt
22 Complex Heredity Polygenic Inheritance One trait is controlled by several genes and possibly environmental factorsGenes may even be located on different chromosomes
23 Complex Heredity Polygenic Inheritance This is a slow process requiring many generations to achieve desired results.Example: Height in humans
24 Complex Heredity Incomplete Dominance = Multiple alleles for a given trait are not expressed over one another, but in combination.Example: RR (Red Flower) x WW (White Flower) = RW (Red and White Striped Flower)X=
25 CodominanceSimilar to incomplete dominance, except characteristics of alleles blend instead of remaining distinctExample: RR (Red Flower) x WW (White Flower) = RW (Pink Flower)X=
26 Heredity in Agriscience Heredity is a huge factor in successful agricultural selective breeding programs.Heredity is manipulated to create high quality HYBRID offspring.
27 Heredity in Agriscience Plants and animals are inbred through several generations to isolate a specific trait or traits.No more than 7 generations are inbred to prevent genetic disorders.
28 Heredity in Agriscience The final generation of two different lines inbred for different traits are crossed producing offspring with the beneficial traits of both lines.Resulting offspring possesses hybrid vigor
33 What is a Punnett Square? A method utilizing the known genotypes of parent offsprings to predict the expression of a given trait or traits in offspring.Must know the genotype of parents and the inheritance pattern of the trait.
34 Using Punnett SquaresWhen using Punnett Squares the Dominant Trait is always represented by an uppercase letterRecessive is lowercaseExample: T=Tall, t=short
35 Using Punnett SquaresA box should be drawn with one space for each allele expressed by both parents.In simple heredity boxes are 2x2.
36 Using Punnett SquaresThe alleles for one parent should be placed above each column at the top, with the alleles for the other placed beside each row on one side.TTTt
37 Using Punnett SquaresThe alleles of each parent should be distributed across and down the box.TTTTTTTtTtTt
38 Using Punnett Squares TT-Homozyous Dominant Tt-Heterozygous Genotype Ratio:3:1:0Phenotype Ratio:4:0TTTTTTTtTtTt
39 Using Punnett SquaresWhen crossing using complex heredity boxes are 4x4 and two different traits are being crossed.